AN ADAPTIVE APPROACH TO CHANNEL MANAGEMENT ON THE PLATTE RIVER

Transcription

1 Figure < >301 Channel Width Class (meters) Crane Use Availability AN ADAPTIVE APPROACH TO CHANNEL MANAGEMENT ON THE PLATTE RIVER KENT PFEIFFER, Platte River Whooping Crane Maintenance Trust, 6611 W. Whooping Crane Dr., Wood River, NE 68883, USA PAUL CURRIER*, Platte River Whooping Crane Maintenance Trust, 6611 W. Whooping Crane Dr., Wood River, NE 68883, USA Abstract: The mission of the Platte River Whooping Crane Maintenance Trust is to protect and manage habitat in the Platte valley for whooping cranes, sandhill cranes, and other migratory birds. The plan for meeting this mission calls for the creation and maintenance of eleven habitat complexes distributed through the central Platte valley. Each habitat complex is intended to consist of 1,000 ha of wet meadows and adjacent roost habitat of open, unvegetated river channel. Reduced flows in the river have caused its channel to narrow with banks that are often heavily wooded. Formerly mobile sand bars have stabilized and support dense stands of willow (Salix spp.) and cottonwood (Populus deltoides) trees. This new type of habitat is unsuitable for roosting sandhill and whooping cranes. As a consequence, the Trust has spent the last 20+ years developing and refining manual techniques for restoring and maintaining open channel habitat. The most effective technique developed to date involves mechanically clearing woody vegetation from islands and accretion ground, followed by (often) annual disking of the sites to prevent reestablishment of vegetation. Currently, approximately 80 km of river channel are managed this way. PROCEEDINGS NORTH AMERICAN CRANE WORKSHOP 9: At the time of settlement by white people, the Platte River was characterized by having several wide braided channels with wet meadows (grassland/wetland complexes) adjacent to and between the channels. Trees were sparse and present as scattered clumps along some of the river banks (Kellogg 1905). However, over the past century the central Platte River valley has undergone a substantial transformation. Numerous dams and water diversions in Wyoming, Colorado, and western Nebraska have significantly reduced natural flows and sediment discharge. Peak discharge has declined nearly 70% and the river channel is only 10-70% of its 1865 width (O Brien and Currier 1987). Nearly annual spring floods, combined with heavy sediment loads, scoured away any vegetation that had established the previous summer. Reductions in flows, and the trapping of sediment behind upstream dams, have dramatically altered the character of the central Platte River. Once wide and treeless channels have now been transformed to multiple narrow channels with woody vegetation succeeding on stabilized sandbars (MacDonald and Sidle 1992). Sidle et al. (1989) concluded that 80% or more of the pre-development channel area had filled with trees between North Platte and Kearney. Substantial channel narrowing had also occurred in the downstream reach between Kearney and Chapman. However, some open channel habitat remains in this reach (Currier et al. 1985, Johnson 1994). Sandhill cranes (Grus canadensis), and whooping cranes (G. americana), prefer to roost in wide (> 200m), open channels (Fig. 1) with shallow sandbars (Krapu et al. 1984, Davis 2001). Not surprisingly, Faanes and LeValley (1993) documented a * deceased Percentage Fig. 1. Width of channel areas used by roosting sandhill cranes in the Platte River, Nebraska. Modified from Davis significant shift in sandhill crane distribution in response to the changes in river channel habitat. In 1957, approximately 60% of cranes were roosting in the Lexington to Kearney reach, but by 1989, only 5% were using that area. Over the same time period, crane use of the Kearney to Chapman reach increased from 9% to 80% of the population. Whooping crane use of the river appears to have followed a similar pattern. Since river flows appear to be inadequate to maintain the channel in the wide-open condition preferred by cranes as roosting habitat, the Platte River Whooping Crane Maintenance Trust ( the Trust ) has implemented a variety of manual efforts to maintain and restore that type of habitat conditions. The first efforts were initiated over 20 years ago and our techniques have continued to evolve since then. 151

2 152 CHANNEL MANAGEMENT ON THE PLATTE Pfeiffer and Currier Proc. North Am. Crane Workshop 9:2005 STUDY AREA The Big Bend reach of the central Platte River valley (the 130 kilometer reach from Overton to Chapman, NE) has hemispherical significance as a staging area for migratory birds. The region is best known for the nearly one-half million sandhill cranes and several million ducks and geese that migrate annually through the region (Sidle et al. 1993). In total, approximately 300 species of birds use the woodlands, wet meadows, and river channel in the valley (Currier et al. 1985). The Platte River Whooping Crane Maintenance Trust was created in 1979 with the mission of acquiring and managing habitat for migratory birds, whooping cranes in particular, in the central Platte valley. The habitat plan developed by the Trust calls for the protection of habitat complexes in each of the eleven bridge segments between Overton and Chapman. Each habitat complex is supposed to consist of at least 1000 ha of native wet meadow centered around suitable roosting habitat for cranes in the river channel itself. To date, we have acquired and protected over 4000 ha of habitat. The Nature Conservancy, National Audubon Society, Nebraska Game & Parks Commission, and U.S. Fish and Wildlife Service own an additional 2400 ha. RESULTS AND DISCUSSION The First Efforts: From the earliest days of the Trust s existence, we recognized that the channel of the Platte River was in a degraded condition as roost habitat for cranes. The ultimate cause of the degradation, reduced flows due to upstream dams and diversions, was beyond our ability to correct. We therefore, began looking for alternative methods to restore and maintain wide, unvegetated channel habitat. The initial experiments on manual control of vegetation in the channel were conducted on the Trust s Mormon Island Crane Meadows property (MICM). At the time, the MICM habitat complex consisted of approximately 700 ha of native grassland adjacent to 14.4 km of river channel. Three separate channels run through or past MICM. The largest channel, locally referred to as the main channel, was m wide and served as an important sandhill crane roost site. However, even this channel had suffered significant tree encroachment along its banks and many formerly mobile sandbars had been stabilized by perennial vegetation. Starting in 1981, we began experimenting with methods for removing the vegetation from islands. Initially, we used two conventional farm tractors, working in concert. The first tractor mounted a 5 ft-wide brush hog mower used to chop down herbaceous vegetation, brush, and small trees. Once the vegetation was mowed, the second tractor, pulling a standard, 12 ft-wide farm disk, would work over the area until it was reduced to bare sand. It was hoped that this treatment would destabilize the islands enough that, when high spring flows did occur, they would become mobilized. This is exactly what happened during the flood event. Unfortunately, such events have only occurred twice ( and 1995) in the past quarter of a century. We discovered that in other years, particularly drought years, vegetation would encroach back to the active river channel, requiring regular maintenance work to keep the channel open. During this time, we also experimented with non-mechanical methods of controlling vegetation, primarily in the form of glyphosate herbicides. The herbicide treatments were effective at killing the vegetation, but they left standing dead material that still needed to be cleared. The herbicide treatments also failed to provide any additional residual control compared to mechanical treatments alone. Consequently, the additional expense and effort involved in herbicide treatments were deemed unjustified and they were discontinued by the late 1980 s. Refining the Techniques: Although it was possible to conduct clearing operations with farm tractors, there were many drawbacks. Tractors were not suited to working in the river. They lacked the mobility needed to negotiate the channel and frequently became stuck. The rough terrain and ubiquitous sand caused extreme wear and tear on the equipment resulting in frequent breakdowns. Partly as a result, we were only able to manage 16 km of river channel from 1981 through 1986, primarily limited to MICM. The first specialized piece of equipment we acquired was a Kershaw Klearway (Fig. 2), a vehicle originally designed to clear trees and brush from railroad right-of-ways. The Klearway is an articulated, 4-wheel drive vehicle capable of operating in water over 1 m deep. It has 2 large flywheels, each with heavy-duty cutting blades, mounted on its front end and can rapidly mow down brush and small (up to 20 cm in diameter) trees. We also custom-built a disk that was larger, more durable, and more disruptive than standard farm disks and began experimenting with vehicles to pull it, including a Steiger articulated 4-wheel drive tractor and Caterpillar D9 bulldozer, before finally settling on a Caterpillar Challenger rubber-tracked tractor (Fig. 3). With this equipment, we were able to expand our clearing activities to an additional 13 km of river channel, including land owned by The Nature Conservancy and National Audubon Society. During this period, it became increasingly apparent that, while islands within the river channel could usually be converted back to mobilized sandbars through clearing, accretion ground (areas where the banks of the river have encroached into formerly active channel) often could not be. In some cases, areas of accretion land were left undisturbed as habitat for woodland birds, particularly neotropical migrants. Generally, though, it was undesirable to leave these woodlands intact as the visual obstruction they present seems to discourage cranes from roosting in the adjacent channel. If some accretion land couldn t be returned to active channel habitat, perhaps it could

3 Proc. North Am. Crane Workshop 9:2005 CHANNEL MANAGEMENT ON THE PLATTE Pfeiffer and Currier 153 Fig. 2. Kershaw used for clearing woody vegetation in the Platte River, Nebraska by the Platte River Whooping Crane Maintenance Trust, Inc. Fig. 3. Caterpillar Challenger rubber-tracked tractor used to maintain open stretches of the Platte River in Nebraska by the Platte River Whooping Crane Maintenance Trust, Inc.

4 154 CHANNEL MANAGEMENT ON THE PLATTE Pfeiffer and Currier Proc. North Am. Crane Workshop 9:2005 be converted to wet meadow habitat? Early attempts at creating new wet meadows from wooded accretion land consisted of simply clearing the trees from an area and allowing it to naturally revegetate. While these areas did develop into a type of habitat similar to native wet meadows, they weren t exactly what we had hoped for. Re-sprouting trees and shrubs were typically abundant and difficult to control. We learned that it was critical to completely kill existing trees and shrubs, including the use of herbicides if necessary, during the initial clearing activity. More recent work on accretion land also included excavation of sloughs and overseeding of the sites with high diversity prairie/ wetland seed mixtures after the removal of woody vegetation. Expansion to Private Lands: By 1996, most of the suitable areas of channel habitat owned by conservation groups were under active management. The majority of sandhill cranes were roosting on those areas (Davis 2001) and many whooping crane sitings occurred there as well. However, conservation groups own only a small proportion of channel habitat in the Platte Valley. Most of it is held by private landowners who farm the adjacent land. Many of these people, having seen the effects of clearing, were interested in having their land cleared as well, albeit for somewhat different reasons than those of the Trust. Generally, landowners along the central Platte either hunt waterfowl or lease their land for that purpose. Geese, and several species of ducks, appear to be as attracted to cleared areas as the cranes. By this time, 68% of sandhill cranes were roosting in cleared areas (Davis 2001) and we were concerned about concentrating too many cranes on too few areas by limiting our clearing activities to conservation lands. We were also well aware that the conservation groups didn t, and possibly never would, control enough river channel habitat to adequately provide for the needs of roosting cranes. With the significant involvement of the U.S. Fish & Wildlife Service s Private Lands Program, clearing activity was expanded to private lands. Demand for clearing proved to be high. By 2002, over 50 landowners had signed agreements allowing us to clear nearly 40 additional km of river channel. The workload quickly reached a point where it was beyond our ability to do it all ourselves and we began subcontracting out much of the work. In fact, a small industry grew up in the central Platte Valley around river clearing, ranging from contractors with bulldozers removing large trees and excavating sloughs to those with Challengers conducting annual maintenance (disking). In all, we are now actively managing approximately 80 km of river channel in the Central Platte Valley with the potential to expand even further. Game & Parks Commission, and over 50 private landowners, is actively managing substantial portions of the Platte River channel. Mechanical clearing has been an expensive and often difficult undertaking, but it has been successful at restoring and maintaining the wide, open-channel habitat preferred by cranes. Although clearing can destabilize islands and, to a lesser extent, accretion ground, it requires high flows in the river to restructure the riverbed and maintain its open character. In two decades, we have moved closer to our habitat goals, but we still are using experimentation, research, and monitoring to understand the habitat, how it responds to our treatments, and how it meets the needs of cranes and other migratory birds. LITERATURE CITED Currier, P.J., G.R. Lingle, and J.G. VanDerwalker Migratory bird habitat on the Platte and North Platte Rivers in Nebraska. The High Pressure Press, Marquette, NE. 177 pages. Davis, C.A Nocturnal roost site selection and diurnal habitat use by sandhill cranes during spring in central Nebraska. Proceedings North American Crane Workshop 8: Faanes, C.A. and M.J. LeValley, Is the distribution of sandhill cranes on the Platte River changing? Great Plains Research (August): Kellogg, R.S Forest belts of western Kansas and Nebraska. USDA Forest Service Bulletin 66: Krapu, G.L., D.E. Facey, E.K. Fritzell, and D.H. Johnson Habitat use by migrant sandhill cranes. Journal of Wildlife Management 48: Johnson, W.C Woodland expansion in the Platte River, Nebraska: patterns and causes. Ecological Monographs 64: Sidle, J.G., H.G. Nagel, R. Clark, C. Gilbert, D. Stewart, K. Wilburn, and M. Orr Aerial thermal imaging of sandhill cranes on the Platte River, Nebraska. Remote Sensing of the Environment. 43: , P.J. Currier, and E.D. Miller Changing habitats in the Platte River valley of Nebraska. Prairie Naturalist 21: MacDonald, P.M. and J.G. Sidle Habitat changes above and below water projects on the North Platte and South Platte Rivers in Nebraska. Prairie Naturalist 24: O Brien, and P.J. Currier Channel morphology and riparian vegetation changes in the Big Bend Reach of the Platte River in Nebraska and minimum streamflow criteria for channel maintenance, Platte River Trust Report. 47 pages. CONCLUSIONS The Trust, in partnership with the U.S. Fish & Wildlife Service, The Nature Conservancy, Audubon Society, Nebraska

5 GREATER SANDHILL CRANE: RESEARCH AND MANAGEMENT IN CALIFORNIA SINCE 1978 RONALD W. SCHLORFF, California Department of Fish and Game, 1416 Ninth Street, Sacramento, CA 95814, USA Abstract: The greater sandhill crane (Grus canadensis tabida) was added to the California list of threatened species in 1983, and the subspecies has been the subject of research and management actions instituted by the California Department of Fish and Game (hereafter Department). Since 1978, the Department has conducted research and recovery actions including periodic breeding ground and wintering area studies, population monitoring, participated in developing Pacific Flyway crane management plans, acquisition and management of key habitats on breeding and wintering grounds, and developed a draft greater sandhill crane recovery strategy. These tasks were accomplished with the assistance of crane researchers and wildlife managers from throughout the United States. Highlights of the Department s program of research, management, and planning activities for greater sandhill cranes are presented. Breeding ground studies indicate a population > 450 pairs exist on private and public lands, primarily in 6 northeastern California counties. Recruitment averaged 5.7% (1.7 sd) in the 1980s-90s. The Department continues actions to facilitate recovery of this threatened subspecies. Threats to cranes and their habitat that may impede recovery efforts are discussed. PROCEEDINGS NORTH AMERICAN CRANE WORKSHOP 9: Key words: breeding, California, greater sandhill crane, Grus canadensis tabida, management, monitoring, planning, population threats, recruitment, research, recovery strategy, threatened species, wintering In 1983, the California Fish and Game Commission added the greater sandhill crane (Grus canadensis tabida) to the State list of threatened bird species. Prior to, and since its listing, the greater sandhill crane has been the focus of a comprehensive Departmental program of research, management, planning, and recovery activities throughout its breeding and wintering ranges in the State. Beginning in 1978, this program has benefited from the assistance of several state and Federal agencies, academics, and the private sector, both inside and outside of California. Notable partners have included the U.S. Fish and Wildlife Service (USFWS) and the U.S. Forest Service (USFS). The Nature Conservancy (TNC) and the State Wildlife Conservation Board (WCB) have played important roles in the acquisition of key crane habitats on breeding and wintering grounds. Researchers from academia and the private sector have participated in important studies. Some private land owners have contributed to the conservation of cranes through sensitive management of habitats on their farms and ranches. Before its listing as a threatened species, the greater sandhill crane had been identified as warranting special consideration; it was an Audubon Red Book species in the 1980 s, it had been selected for Pacific Flyway management planning in 1978, and it was included on the Department s Bird Species of Special Concern in California during The objectives of this paper are to provide an overview of research and management activities and recovery efforts to improve the status of the greater sandhill crane in California. BREEDING AND WINTERING DISTRIBUTION AND ABUNDANCE Breeding Grounds Historical notes indicate California s breeding population of greater sandhill cranes nested in eastern Siskiyou County, northeastern Shasta County, and south to Honey Lake, Lassen County. Breeding records were from near Ft. Crook, Shasta County (1860), and Eagleville near Alturas, Modoc County (Grinnell and Miller 1944). Walkinshaw (1949) estimated that 3-4 pairs had territories in California in 1944; however, no range wide searches for crane territories were conducted during those earlier years. Historically, breeding records tended to be from incidental sightings, not suitable for developing past to present population trend data. Recent surveys have been more intensive. Baseline population estimates have been developed from increasingly intensive surveys in 1971, 1981, 1988, and 2000 (Littlefield 1982, 1989; Littlefield et al. 1994; Ivey and Herziger 2001; Table 1; Fig. 1). Recent surveys revealed that wetland and meadow habitat on private and public lands in Lassen, Modoc, Plumas, Shasta, Sierra, and Siskiyou counties constitute the current breeding grounds in California. In the 2000 survey (Table 1) 465 breeding pairs were recorded as follows: Modoc (252), Lassen (122), Siskiyou (51), Plumas (20), Shasta (10), and Sierra (10). Breeding pair estimates have ranged from 112 breeding pairs in 1971 in 3 of the above 6 counties to 465 pairs in 2000 in 6 counties (Table 1). Wintering Grounds After young fledge, cranes concentrate at grain fields near favorable roost sites. They confine most of their activities within these habitats until fall migration. Important fall foods include barley, rye, wheat, and oats. Fields used consistently by cranes are often within 6 km of a shallow wetland which serves as a 155

6 156 GREATER SANDHILL CRANES IN CALIFORNIA Schlorff Proc. North Am. Crane Workshop 9:2005 Table 1. Greater sandhill crane breeding population estimates in 6 northeastern California counties (Lassen, Modoc, Plumas, Shasta, Sierra, and Siskiyiou), Year Survey months Breeding pairs Source 1971 March-April 112 a Littlefield et al March - May 191 b Littlefield March - August 277 b Littlefield April - June 465 b Ivey and Herziger 2001 a Lassen, Modoc, Shasta counties only b Lassen, Modoc, Plumas, Shasta, Sierra, and Siskiyiou counties. communal roost site (Littlefield 1986). Once cranes leave pre-migration staging areas, they fly south to southwest to wintering grounds in the Central Valley of California from near Chico, Butte County, south to Delano, Kern County (Fig. 2; Littlefield and Thompson 1979, Pogson 1990, Pogson and Lindstedt 1988, 1991; Pacific Flyway Council 1997). Small numbers (< 1000) of Lower Colorado River Valley Population (LCRVP) of greater sandhill cranes primarily winter in Imperial County, California (Fig. 3; Pacific Flyway Council 1995). These cranes breed mainly in Utah and Nevada, and most winter in Arizona. Flocks of lesser sandhill cranes (G. c. canadensis) and some Canadian sandhill cranes (G. c. rowani) also winter in the Central Valley. Suitable roosts and nearby abundance of cereal grain crops are requisites for wintering cranes. Rice is the most important food crop for wintering cranes in the northern Central Valley and corn is used on the remainder of the wintering ground, particularly in the Sacramento-San Joaquin River Delta (hereafter Delta) (Littlefield and Thompson 1979, Pogson and Lindstedt 1988). Irrigated pastures also are used extensively as loafing and feeding sites at some areas (Pogson and Lindstedt 1988). Both the abundance and availability of agricultural food crops are critical for cranes wintering in California. Attempts to estimate the wintering population of greater sandhill cranes are difficult because 3 currently recognized subspecies annually inhabit the Central Valley from about mid-september to early March. However, several researchers obtained winter sandhill crane population estimates at various locations in the1960s- early1990s (Table 2). RESEARCH AND MONITORIING Early Activities Prior to establishing the Department s coordinated research program in 1978, there were a number of incidental and systematic sources of information used to track the status of cranes breeding and wintering in California. From the 1940s-50s and continuing to the present, Department, other agency, and private sector individuals reported sightings of cranes on both breeding and wintering grounds (Naylor et al.1954, Littlefield 1973). Since about 1960, during aerial breeding and wintering waterfowl surveys, Department personnel recorded cranes along with ducks and geese. Various individuals have conducted studies on breeding and wintering crane populations, with the most notable studies in the 1970s-80s (Littlefield 1973, Littlefield and Thompson 1979, Pogson and Lindstedt 1988). Herter (1982) conducted a lesser sandhill crane banding study in the Central Valley, and Pogson (1990) and Pogson and Lindstedt (1988, 1991) studied crane winter habitat use in the Central Valley Present Activities In 1978, the Department initiated its crane research and monitoring program on both the breeding and wintering grounds; Department personnel also participated in developing Pacific Flyway Management plans for all cranes breeding and wintering in California. Plans focusing on the greater subspecies initially formed the basis for the Department s research and management activities, and later, they served as a model for

7 Proc. North Am. Crane Workshop 9:2005 GREATER SANDHILL CRANES IN CALIFORNIA Schlorff 157 Sandhill Crane Breeding Population Distribution Data Source: Department of Fish and Game California Wildlife Habitat Relationships Program (CWHR) Miles Fig. 1. Breeding distribution of greater sandhill cranes in California.

8 158 GREATER SANDHILL CRANES IN CALIFORNIA Schlorff Proc. North Am. Crane Workshop 9:2005 Sandhill Crane Winter Range Data Source: Department of Fish and Game California Wildlife Habitat Relationships Program (CWHR) Miles Fig. 2. Winter distribution of the Central Valley Population of greater sandhill cranes in California.

9 Proc. North Am. Crane Workshop 9:2005 GREATER SANDHILL CRANES IN CALIFORNIA Schlorff 159 LCRVP Distribution Data Source: Department of Fish and Game California Wildlife Habitat Relationships Program (CWHR) Miles Fig. 3. Winter distribution of the Lower Colorado River Valley Population of greater sandhill cranes in California.

10 160 GREATER SANDHILL CRANES IN CALIFORNIA Schlorff Proc. North Am. Crane Workshop 9:2005 Table 2. Sandhill crane wintering population estimates, Central Valley of California, 1960s Year Location No. cranes Source 1960 s to 70 s Butte Sink a 3,000-3,200 b Littlefield and Thompson Central Valley 6,800 c Pogson and Lindstedt Butte Sink 4,900-6,800 b Littlefield Delta d 6,000-14,000 e Schlorff 2001 a Butte and Sutter counties, all subspecies b Reported as greater subspecies c Reported as large cranes d Sacramento-San Joaquin Delta e Five aerial counts by the author; all 3 subspecies included recovery planning in the State (Pacific Flyway Council 1995, 1997). A 1981 breeding ground study, primarily in the northern counties of Modoc, Siskiyou, Lassen and Shasta, found a small population of greaters nesting primarily on private lands (Littlefield 1982, Table 1); additional cranes were scattered on National Forest lands. This study built upon Littlefield s (1973) earlier research in 1971 on some of the same areas (Table 1). Following the 1981 study, key breeding areas were periodically monitored (Schlorff 1987) by both ground and aerial surveys. In the late 1970s-80s, the Department also began annual air and ground monitoring of wintering cranes to locate concentration areas, determine habitat use, identify key roosting areas, record marked bird observations, and obtain winter population recruitment estimates (Schlorff 1981, 1982, 1987; Table 3). In , Department personnel attempted to capture and mark greater sandhill cranes at several wintering locations, but this was unsuccessful due to the difficulty in attracting cranes to baited trapping sites when abundant food was available elsewhere (Schlorff 1987). While the Department was initiating studies in California, there already was a program of ongoing research and banding at the Malheur National Wildlife Refuge ( NWR), Oregon (Littlefield 1968, Littlefield and Ryder 1968, Littlefield 1976). In the 1980 s and 1990 s color-marking continued at Malheur NWR, and also began at the Modoc NWR, Modoc County, California, in cooperation with the Department s crane research program (Littlefield 1985, Des Roberts 1992, 1997). Many observations of cranes banded at these 2 refuges were made by Department personnel on Central Valley wintering sites. The cooperation between NWR personnel in Oregon and California was critical in assisting the Department s ongoing and expanding crane research and management programs. Additionally, banding and other breeding ground research were conducted by TNC at the Sycan Marsh in southern Oregon during the 1980s (Stern et al. 1986). Although Department research and monitoring activities have continued to the present, annual efforts have not been consistent. Highlights of research and monitoring include some recent comprehensive studies on both the breeding and wintering grounds in California (Littlefield 1993a,b, Littlefield et al. 1994, Ivey and Herziger 2001, 2003). This may partially be explained by Department s recent effort to write a recovery plan for greater sandhill cranes, but there have been data gaps in the 1990s-2000s that have hindered plan development (CDFG, Recovery Planning Strategy for the Greater Sandhill Crane, in preparation). For example, an accurate wintering population estimate for all 3 subspecies of sandhill cranes is critical for setting a recovery target number for greaters. Contrasting the difficulties of obtaining wintering population estimates by subspecies, breeding ground research has been less challenging because only the greater subspecies nests in California. However, because of problems associated with accurate identification of 3 subspecies, their relative winter population number estimates do not exist. Breeding ground studies completed in the 1970s-80s showed a lower crane population than estimated in 2000 (Table 1). But these results, ranging from 122 pairs in 1971 to 465 pairs in 2000, also suggest differential survey effort has biased estimating the number of breeding cranes in California. The apparent increase may not be all due to breeding population growth since earlier surveys involved much time and effort in locating breeding pairs and sites used. Later surveys solved some of these problems with the use of aircraft. However, Littlefield et al. (1994) reported individual breeding locations, within the larger northeastern California study area, where crane pairs did increase from 1971 to 1981 and again in When the fourth population estimate was made in 2000, these same 5-6 sites continued to show an increase in breeding pairs (Ivey and Herziger 2001). Additional monitoring will be necessary to refine methodology, assess population estimates, and to track the subspecies recovery in

11 Proc. North Am. Crane Workshop 9:2005 GREATER SANDHILL CRANES IN CALIFORNIA Schlorff 161 the State. THREATS TO CRANES AND MANAGEMENT RECOM- MENDATIONS Existing Management for Sandhill Cranes Since its listing as a threatened species in 1983, the greater subspecies has received elevated management attention in California (Schlorff 1994, Pacific Flyway Council 1995, 1997). In addition to improved crane management on existing NWRs and State Wildlife Areas (WAs), additional habitat has been acquired by state and federal agencies and the private sector. This has included Department recommended land acquisitions in Modoc and Lassen counties (Ash Creek WA) and in the San Joaquin Valley (Woodbridge Ecological Reserve) in the 1980s. Some wetland easements include the Natural Resource Conservation Service Water Bank Program, which has temporarily protected some crane territories in Modoc County. Lands managed under the NWR system and TNC preserve properties have provided additional habitat on both breeding and wintering grounds in California (Littlefield and Ivey 2000). National Forest lands, particularly in Lassen and Modoc counties, also provide important crane breeding habitats (Littlefield 1982, 1989, Ivey and Herziger 2001). A program of breeding habitat acquisition and other management strategies, on both private and public lands, to protect wetlands used by nesting greater sandhill cranes will be essential in achieving recovery objectives. Cranes generally are found breeding and wintering in natural wetland ecosystems and also use certain agricultural lands, therefore, by protecting these habitats additional species, including waterfowl and other birds, could also benefit. Private Land-Use Increased demand for crops such as alfalfa could lead to extensive private land conversions in the primary crane breeding areas. Such land use conversions could eliminate breeding cranes from some private lands in California. Pursuing large scale acquisitions may not be as practical as on the wintering grounds, although it may be an important management strategy for ensuring the protection of critically important breeding habitat. Acquiring conservation easements and purchasing key parcels of private land from willing sellers could help recover the greater subspecies in the state. If the current small breeding population is to be increased in the near future, it will be necessary to maximize crane production on certain public lands. Wintering cranes in the Central Valley currently depend on certain agricultural practices and cropping patterns that are compatible with their daily and seasonal foraging and non-foraging activities (Pogson and Lindstedt 1988, 1991). Cranes concentrate primarily on private lands and are vulnerable to land-use changes that alter feeding, loafing, and roosting habitats (Pogson and Lindstedt 1988, Littlefield 1993a, Schlorff 1994). Other than purchasing key parcels to ensure that critical roosting and loafing sites are available and free from disturbance, there is relatively little habitat on private lands that can be protected or actively managed specifically for cranes by governmental agencies. Most important feeding areas are on large private lands in the Central Valley. The only means that governmental agencies have to ensure continued availability of these lands for cranes may be through cooperative agreements, purchase of conservation easements, and other incentives to induce private landowners to manage a portion of their lands for cranes. The private sector, therefore, clearly holds the key to the future survival of crane populations on both the wintering and breeding grounds in California. Waterfowl Management Impacts The Department has acquired lands that once supported large flocks of foraging cranes. Rogers (1990) reported that 90% of the Little Dry Creek Unit (LDCU) of the Upper Butte Basin WA was cultivated rice land and had been documented as important foraging habitat for cranes before its conversion to wetlands for waterfowl (Pogson and Lindstedt 1988, 1991). Thus, management actions to create wetlands, to provide waterfowl habitat and hunting opportunity, should be designed to minimize potential conflict with the requirements of sandhill cranes wintering in the same areas. Littlefield (1993b) conducted research on crane foraging habitats and potential conflict with public use, including hunting and other activities, at State WAs. Littlefield (1993b) also investigated the impact of human disturbance on cranes at LDCU and surrounding agricultural fields. His findings indicated that disturbance due to all forms of human activities are often sporadic, short in duration, and potentially controllable. Human disturbance probably can be reduced further by specific management actions, including adjustments in timing and locations of hunting areas, and screening of disturbing activities from crane use areas by planting concealing vegetation such as willows (Salix spp.). Conversion of certain croplands to seasonal wetlands on WAs and elsewhere, primarily for waterfowl hunting, has reduced availability of crane foraging habitat in the Central Valley (personal observation). A percentage of cropland, such as rice, needs to be available to cranes to fulfill their foraging habitat requirements on the wintering ground. However, even with an abundance of rice fields, flooding them beyond a certain depth makes the waste grain unavailable to foraging cranes (Littlefield 2002). It is important to acquire, in fee title and through conservation easements, additional lands and apply management sensitive to the habitat requirements of cranes. Existing public lands that support cranes could be enhanced with proper management of natural and agricultural habitats. The challenge now facing the Department, and certain NWRs, is to provide a balance of habitats to meet the needs of greater sandhill cranes

12 162 GREATER SANDHILL CRANES IN CALIFORNIA Schlorff Proc. North Am. Crane Workshop 9:2005 on private and public lands in concert with reducing conflicts caused by certain human activities, such as hunting. Since many of these lands currently or potentially can have a great number of wintering cranes, the recovery of the greater subspecies in California may depend upon successfully meeting this challenge. Predation Predation has limited sandhill crane productivity at Malheur NWR (Littlefield 1985, Littlefield and Cornely 1997, Ivey and Scheuering 1997). When lethal control was implemented, it reduced the impact of certain predators on nesting cranes (Littlefield and Cornely 1997). Predation trends in California involving coyote (Canis latrans), common raven (Corvus corvax), and raccoon (Procyon lotor) should be monitored closely and selected predators controlled if necessary (Littlefield 1989). Common ravens have increased significantly throughout the crane nesting range in California since 1981, and coyotes were regularly seen in many nesting areas in 1988, particularly Ash Valley, Lassen County, Sierra Valley, Plumas and Sierra counties, and lower Klamath NWR, Siskiyou County (Littlefield 1989, 1995). Nagendran (1993, 1994) found that low water levels in nesting wetlands increased losses to predators, such as coyotes; at Ash Creek WA, only 2 of 22 young cranes fledged in While predator control, principally for coyotes, occurs on many private lands, it also may be needed on certain public lands that support nesting cranes in the State. Actions to reduce predation on cranes at Malheur NWR have resulted in significantly improved nesting success (Littlefield and Cornely 1997; Littlefield 2003). Crane productivity needs to be periodically monitored; if it is found that persistently low recruitment rates are occurring in particular regions, then more intensive nesting studies should be initiated. California crane recruitment is low compared to other populations (Schlorff 1994, Drewien et al. 1995, Table 3), thus annual recruitment surveys are needed. If predation is deemed a major factor affecting crane recruitment, then control measures may be warranted. Collision Mortality Power line marking devices have been used successfully on Modoc NWR to reduce collision mortality in cranes (C. Bloom, U.S. Fish and Wildlife Service, personal communication). Marking devices often include large orange plastic globes attached at intervals on power lines coinciding with known regular flight paths. However, few of these devices have been used within the California crane nesting and wintering areas. Although power line marking devices are important for reducing collision mortality in crane nesting areas, they also may be especially needed near winter roosting and feeding sites in the Central Valley. As many as 22 cranes were killed in a single day as birds were leaving a roost site on a foggy morning (T. Pogson, personal communication). Most likely this type of loss can be reduced with power line markers. Power line mortalities have been reduced at some crane concentration areas in Oregon, Colorado, New Mexico, Wyoming, and the Modoc NWR, California with line marking devices (Brown and Drewien 1995, D. Lockman, Wyoming Game and Fish Department, and C. Bloom, U.S. Fish and Wildlife Service, personal communication). In cooperation with utility companies, a marking program should be tested on perennial problem power lines in the Central Valley wintering area to assess their effectiveness. RECOVERY PLANNING Background and Existing Actions Since 1978, the Department participated with other Pacific Flyway states to develop crane management plans. These plans also could be modified to produce a recovery plan in accordance with the 1997 amendments to the California Endangered Species Act (CESA). Specific management recommendations are contained in the Pacific Flyway Management plans for the CVP and LCRVP greater sandhill cranes (Pacific Flyway Council 1995, 1997). Those portions of Pacific Flyway Plans germane to California could, with refinements, form the basis for a recovery planning and implementation schedule for the State. The Pacific Flyway Plans contained several recommended research and management tasks that would be necessary for recovery of the greater subspecies in California (Pacific Flyway Council 1995, 1997). When the greater sandhill crane was added to the list of threatened species in 1983, all populations breeding or wintering in the State were protected by CESA. This listing action was the first recovery step for the subspecies. The CESA provides that any activities that benefit or impact the subspecies be scrutinized by the State to protect crane populations and their habitats. The CESA also specified that appropriate steps be taken that would lead to recovery and delisting of the subspecies in California in a timely fashion. Several years before the 1997 amendments of CESA required a formal recovery planning strategy for listed species (California Department of Fish and Game 2003), the Department had already taken some important steps toward the recovery of the subspecies by acquiring key habitats that had been identified as important for both nesting and wintering cranes (Littlefield 1982, 1989; Pogson and Lindstedt 1988, 1991). Two winter roost site acquisitions were funded by the Wildlife Conservation Board in based upon Department recommendations from wintering ground studies in San Joaquin County (Schlorff 1981, 1982, 1987). On the breeding ground, State WAs are to consider the needs of cranes in management of those lands. The Ash Creek WA, was identified as a key breeding area by Littlefield (1982, 1988), and is currently the largest State WA supporting breeding cranes.

13 Proc. North Am. Crane Workshop 9:2005 GREATER SANDHILL CRANES IN CALIFORNIA Schlorff 163 Recovery Goal and Strategy The ultimate goal of the California greater sandhill crane recovery strategy is to improve the status of the subspecies through a variety of specific habitat protection and other actions so that protections provided by CESA are no longer necessary, and delisting can be proposed (California Department of Fish and Game 2003). To accomplish this objective, the Department assembled a recovery team composed of members with various expertise and special interests. The Recovery Strategy Team had representatives from state and federal agencies, conservation groups, and private land owners. Species recovery is dependent upon specific actions in areas of habitat protection, habitat management, habitat enhancement, predator management, interpretive programs, and scientific research. The draft plan addresses these key elements: 1. Interim and long-term population goals. 2. Interim and long-term funding needs for planning and implementing the recovery strategy. 3. A range of conservation measures designed to lead to the recovery of the subspecies with flexibility to modify those measures based on research findings and population monitoring results. 4. An estimate of the time required to achieve recovery based on a range of possible management and other recovery actions such as private landowner incentives to protect or enhance habitat. 5. A list of tasks and agency/group responsibilities needed to achieve recovery of the subspecies. 6. A mechanism to monitor the progress of recovery and identify milestones of success or any other actions needed in order to reach stated interim and/or long-term recovery goals, and the flexibility to alter those actions based on new information. 7. Criteria and procedures for changing the status of the subspecies should recovery be achieved or the population and habitat status deteriorate further. 8. A schedule of research and management actions necessary to implement the recovery strategy. 9. List of actions to receive additional funds following completion of the planning phases of the recovery strategy (e.g., research studies, habitat management). The recovery team and the Department will solicit and consider the input of all affected and interested parties during the development of the recovery strategy plan. After peer review and modification, the Department will present the completed recovery strategy plan to the California Fish and Game Commission for adoption. The Department will assume the responsibility for implementing the plan s actions and recommendations for the recovery of greater sandhill cranes in California. ACKNOWLEDGMENTS Many people have participated in the Department s sandhill crane research and management program over the years; I especially wish to acknowledge the valuable contributions of researchers C.D. Littlefield, T.H. Pogson, S.M. Linstedt, G.L. Ivey, and C.P. Herziger. I also wish to thank the several Department employees and others who worked independently or assisted me in collecting field data over 2 decades, including J.A. Estep, B. Deuel, and J. Snowden. The staffs of the Malheur NWR and the Modoc NWR have been active in sandhill crane research and management for many years and their assistance to the Department was invaluable. Some private land owners in the State have implemented management activities on their properties that are sensitive to the needs of cranes. Private sector conservation organizations such as TNC as well as the State s WCB have acquired several key habitats for cranes. The members of the sandhill crane recovery team deserve special note for their efforts in developing a first draft of a recovery strategy for cranes in California. I am grateful for the editorial comments of R. C. Drewien, P. Hofmann, C. D. Littlefield, M. L. Morrison, D. T. Steele, and D.Yparraguirre on drafts of this manuscript. LITERATURE CITED Brown, W. M., and R. C. Drewien Evaluation of two power line markers to reduce crane and waterfowl collision mortality. Wildlife Society Bulletin 23: California Department of Fish and Game Greater sandill crane Recovery Strategy Plan. (Draft). California Department of Fish and Game, Sacramento, California, USA. DesRoberts, K.J Radio telemetry study of greater sandhill crane chicks on Modoc National Wildlife Refuge, California. Modoc National Wildlife Refuge, Alturas, California, USA Survival and habitat use of greater sandhill crane colts on Modoc National Wildlife Refuge, California. Proceedings of the North American Crane Workshop 7: Drewien, R. C., W. M. Brown, and W. L. Kendall Recruitment in Rocky Mountain greater sandhill cranes and comparison with other crane populations. Journal of Wildlife Management 59: Grinnell, J. and A. H. Miller The distribution of the birds of California. Cooper Ornithological Club 27, Berkeley, California, USA. Herter, D.R Habitat use and harassment of sandhill cranes staging on the eastern Copper River Delta, Alaska. Thesis, University of Alaska, Fairbanks, Alaska, USA. Ivey, G.L., and C. P. Herziger Distribution of greater sandhill crane pairs in California, California Department of Fish and Game, Sacramento, California, USA.

14 164 GREATER SANDHILL CRANES IN CALIFORNIA Schlorff Proc. North Am. Crane Workshop 9:2005 and Sandhill crane monitoring at Staten Island, San Joaquin County, California, Unpublished Report. Consumnes River Preserve, Galt, California, USA. and E.J. Scheuering Mortality of radioequipped sandhill crane colts at Malheur National Wildlife Refuge, Oregon. Proceedings of the North American Crane Workshop 7: Littlefield, C. D Breeding biology of the greater sandhill crane on Malheur National Wildlife Refuge, Oregon. Thesis, Colorado State University, Fort Collins, Colorado, USA Report on sandhill cranes for Baja California, California, Oregon, Washington and Alaska. Sandhill Crane Committee Report, Burns, Oregon, USA Productivity of greater sandhill cranes on Malheur National Wildlife Refuge, Oregon. Pages in J.C. Lewis, editor. Proceedings International Crane Workshop, International Crane Foundation, Baraboo, Wisconsin, USA The status and distribution of greater sandhill cranes in California, California Department of Fish and Game, Wildlife Management Branch, Administrative Report 82-1, Sacramento, California, USA.. Radio-telemetry studies of juvenile greater sandhill cranes on Malheur National Wildlife Refuge, Oregon. Malheur National Wildlife Refuge, Oregon Autumn sandhill crane habitat in southeast Oregon. Wilson Bulletin 98: Status of greater sandhill crane breeding populations in California, California Department of Fish and Game, Wildlife Management Division, Nongame Bird and Mammal Section Report, Sacramento, California, USA a. Greater sandhill crane assessment in the Upper Butte Basin, California California Department Fish and Game, Rancho Cordova, California, USA b. Annual assessment and monitoring report for greater sandhill cranes and other threatened and endangered species on the Little Dry Creek Unit, California. California Department of Fish and Game, Rancho Cordova, California, USA Greater sandhill crane nesting and production in northeastern California, Western Birds 26: California Dept. of Fish and Game, Rancho Cordova, California Winter foraging habitat of greater sandhill cranes in northern California. Western Birds 33: Sandhill crane nesting success and productivity in relation to predator control in southeastern Oregon. Wilson Bulletin 115: and J.E. Cornely Nesting success and production of greater sandhill cranes during experimental predator control at Malheur National Wildlife Refuge, Oregon, Malheur National Wildlife Refuge, Oregon, USA. and G. L. Ivey Conservation assessment for greater sandhill cranes wintering on the Cosumnes River Floodplain and Delta regions of California. Unpublished report. The Nature Conservancy, Cosumnes Preserve, Galt, California, USA. and R.A. Ryder Breeding biology of the greater sandhill crane on Malheur National Wildlife Refuge, Oregon. Transactions North American Wildlife Conference 33: , M.A. Stern, and R.W. Schlorff Summer distribution, status, and trends of greater sandhill crane populations in Oregon and California. Northwestern Naturalist 75:1-10. and S.P. Thompson Distribution and status of the Central Valley population of greater sandhill cranes. Pages in J.C. Lewis, editor. Proceedings 1978 Crane Workshop. Colorado State University Printing Service, Fort Collins, Colorado, USA. Nagendran, M Study to determine nesting success, natality and causes of chick mortality of greater sandhill cranes breeding at Ash Creek Wildlife Area, California. Final report, Yosemite Center for Wildlife Conservation, Merced, California, USA A study and a survey of sandhill crane, waterfowl and shorebird broods at Ash Creek Wildlife Area, California. Final report, California Department of Fish and Game, Redding, California, USA. Naylor, A.E., A.W. Miller, and M.E. Foster Observations on the sandhill crane in northeastern California. Condor 56: Pacific Flyway Council Pacific flyway management plan for the Lower Colorado River Valley Population of Greater Sandhill Cranes. Unpublished report. Pacific Flyway Study Committee, U.S. Fish and Wildlife Service, Portland, Oregon, USA Pacific flyway management plan for the Central Valley Population of Greater Sandhill Cranes. Unpublished report. Pacific Flyway Study Committee, U.S. Fish and Wildlife Service, Portland, Oregon, USA. Pogson, T.H Distribution, abundance and behavior of greater sandhill cranes (Grus canadensis tabida) wintering in California s Central Valley. Thesis, University of Alaska, Fairbanks, Alaska, USA. and S.M. Lindstedt Abundance, distribution and habitat of Central Valley population greater sandhill cranes during winter. Unpublished report. Fairbanks, Alaska, USA. and Distribution and abundance of large sandhill cranes, Grus canadensis, wintering in California s Central Valley. Condor 93: Rogers, R. D Gray Lodge Wildlife Area Upper Butte

15 Proc. North Am. Crane Workshop 9:2005 GREATER SANDHILL CRANES IN CALIFORNIA Schlorff 165 Sink unit management plan. California Department of Fish and Game, Sacramento, California, USA. Schlorff, R.W Winter sandhill crane inventory. Job Progress Report, Project W-54-R-13, California Department of Fish and Game, Sacramento, California, USA Winter sandhill crane inventory. Job Progress Report, Project W-54-R-14, California Department of Fish and Game, Sacramento, California, USA Sandhill crane research and management. Job Final Report, Project W-65-R-4, California Department of Fish and Game, Sacramento, California, USA year status review: greater sandhill crane (Grus canadensis tabida). California Department of Fish and Game, Wildlife Management Branch, Sacramento, California, USA Aerial survey data on wintering sandhill cranes in the Sacramento-San Joaquin Delta. California Department of Fish and Game, Habitat Conservation Planning Branch, Sacramento, California, USA. Stern, M., G. Pampush, K. Kristensen, and R. Del Carlo Survivorship, causes of mortality and movements of juvenile sandhill cranes at Sycan Marsh, Oregon, Unpublished report, The Nature Conservancy, Portland, Oregon, USA. Walkinshaw, L. H The sandhill cranes. Cranbrook Institute of Science Bulletin No. 29, Bloomfield Hills, Michigan, USA.

16 166 Proc. North Am. Crane Workshop 9:2005

17 SANDHILL CRANE USE OF MANAGED CHUFA WETLANDS IN NEW MEXICO JOHN P. TAYLOR 1, U.S. Fish and Wildlife Service, P. O. Box 1246, Socorro, NM 87801, USA LOREN M. SMITH, Wildlife and Fisheries Management Institute, Texas Tech University, P. O. Box 42125, Lubbock, TX , USA Abstract: Natural wetland food plants help meet energetic requirements for sandhill cranes (Grus canadensis). Chufa (Cyperus esculentus) tubers were found to be a prominent item in the winter diet of cranes in New Mexico and Texas. In 1996 and 1997, chufa production was compared among mowing, discing, and sustained-flooding treatments intended to enhance chufa tuber growth. Sandhill crane numbers were monitored on wetlands during winter flooding to determine treatment preferences. No differences in sandhill crane use of treated wetlands were found in 1996, however in 1997, crane use was higher on disked field than sustained flood fields with mowed fields recording similar use levels as other treatments. Regression analysis also was used to explore the relationship between crane use and above and belowground food production. Chufa mass and fall panicum (Panicum dichotomiflorum) seed were positively related to crane use. We hypothesize cranes used wetlands where high biomass of these above and belowground food items was available to efficiently meet daily energetic needs. Disking wetlands at a depth of 5 cm about 30 days following initial wetland drawdown may be an effective treatment to expand chufa production and attract sandhill cranes. PROCEEDINGS NORTH AMERICAN CRANE WORKSHOP 9: Key words: chufa, Cyperus esculentus, Grus canadensis, moist-soil management, New Mexico, sandhill cranes, wetlands. Behaviorally and physiologically important events for sandhill cranes (Grus canadensis) occur on wintering areas. Wintering areas must not only provide for the immediate survival of the species, but for subsequent reproduction (Tacha and Vohs 1987, Krapu and Johnson 1990). Chufa provides 4.26 kcal/g of gross energy (Knaur 1977, Kelley 1986, Fredrickson and Reid 1988) and can potentially meet daily energetic requirements in winter. The tubers are 45 to 77% carbohydrates (mostly starch) and 10 to 14% lipids (Matthiesen and Stoller 1978, Addy and Eteshola 1984, Kelley and Fredrickson 1991). Foods with good lipid composition, such as chufa, can allow cranes to rapidly accumulate g/day of fat (Krapu et al. 1985, Krapu and Johnson 1990). Considering that estimated energy requirements for post-breeding greater sandhill cranes (G. c. tabida) at 0 C in New Mexico are about kcal/ bird/day (Kendeigh et al. 1977, Reinecke and Krapu 1986), chufa represents a potentially important natural food item able to meet these needs. Chufa tubers are a prominent item in sandhill crane and whooping crane (Grus americana) diets on wintering areas. In south Texas, chufa tubers composed over 50% of food volume for sandhill cranes and comprised the bulk of foods eaten (Guthery 1976). In irrigated agricultural valleys of New Mexico, tubers comprised up to 19% of the food volume eaten by sandhill cranes (Walker and Schemnitz 1987). Hunt and Slack (1987) reported that chufa tubers made up 43% of the food volume of a whooping crane shot near Aransas National Wildlife Refuge in Texas. Although there is information regarding the use of chufa as 1 Deceased a food resource by sandhill cranes, information on the response by sandhill cranes to specific wetland management practices to enhance chufa production (Taylor and Smith 2003) is lacking and would be helpful to managers on wintering areas. Therefore, our objectives were to determine sandhill crane preferences for specific chufa production treatments and to explore relationships between crane use and available foods. STUDY AREA The study was conducted at the Bosque del Apache National Wildlife Refuge (NWR) (33 48, ) in the Middle Rio Grande Valley of central New Mexico, USA. The Middle Rio Grande basin is bounded by mountain ranges rising 2,000 m to the west and 1,600 m to the east and spans both the Chihuahuan desert scrub and semidesert grassland biotic communities (Brown and Lowe 1980, Brown 1982). Climate is characterized by high light intensity, low relative humidity, high evapotranspiration, and variable rainfall (Johnson 1988). From 1988 to 1997, annual precipitation averaged 24.9 cm with about 50% occurring between 1 July and 30 September (Bosque del Apache NWR NOAA weather station data). During these same years, the average maximum air temperature was 36 C and the average minimum temperature was -8 C. Irrigation water is diverted from the Rio Grande north of the refuge and is delivered via irrigation canals and drains for agricultural, wetland, and riparian use. Fifteen moist-soil wetlands, ranging in size from 0.9 to 5.8 ha served as experimental units for treatment comparisons designed to enhance belowground plant food, primarily chufa, production (Taylor and Smith 2003). Each wetland was served by an interior feeder canal and feeder drain to provide independent field irrigation capability. Wetland soils were domi- 167

18 168 CRANE USE OF CHUFA WETLANDS Taylor and Smith Proc. North Am. Crane Workshop 9:2005 nated by clays and clay loams. All fields were laser leveled to a % grade and have shallow water impoundment potentials of up to 45 cm depth. METHODS Chufa Production Treatments We randomly assigned mowing, disking, and sustained flooding treatments to wetlands in the study area to assess chufa production enhancement strategies in spring and summer 1996 and All fields were initially flooded in early April each year and subsequently received 12 irrigations representing an average flood interval of days through the end of August (Taylor and Smith 2003). In the mowed treatment, cocklebur (Xanthium strumarium) mowing occurred about 2 months after initial drawdown when cocklebur plants were about 15 cm in height to reduce potential competition with chufa through shading (Wills 1975, Jordan-Meloro and Stoller 1978, Keeley and Thullen 1978, Patterson 1982). The disking treatment consisted of disking to a depth of 5 cm 30 days after initial wetland drawdown in an attempt to maximize chufa tuber production through vegetative reproduction (Thumbleson and Kommedahl 1962, Taylorson 1967, Sanchez Tames and Vieitez 1970, Thullen and Keeley 1975, Kelley 1986). The sustained flood treatment required prolonged (70 hours) periods of flooding to drown herbaceous vegetation competing with chufa plants (Merrell 1975). Winter Flooding Flooding occurred on the 15 fields during the and winter seasons. In order to provide feeding habitat for migratory birds over the entire winter period, we did not flood all fields at the same time. Instead, floodup occurred on 3 randomly chosen fields representing each treatment type on 5 occasions each winter. This variation due to floodup period was removed using a randomized block design. The 5 floodup time periods occurred 23 December 1996, 6 and 20 January 1997, and 3 and 17 February 1997 during the winter, and 22 December 1997, 5 and 19 January 1998, and 2 and 16 February 1998 during the winter. During both winters, we inundated wetlands within 24 hours to a depth of cm for the 2 week period specified, and then immediately drained them. Sampling Methods Above and belowground production (g/m 2 ) of specific food items was determined for each field. Aboveground seeds, including chufa, bearded sprangletop (Leptochloa facicularus), barnyard grass (Echinochloa crusgalli), yellow bristlegrass (Setaria glauca), Eriochloa spp., Johnson grass (Sorghum halepense), and fall panicum, were clipped, dried and weighed. Chufa tubers, Johnson grass rhizome, and field bindweed (Convolvulus arvensis) rhizome biomass were obtained from soil samples after being washed, separated, dried, and weighed (Taylor and Smith 2003). During floodup periods each winter, sandhill cranes were counted 3 days per week on each of 3 treatment fields from hourly using a 60x spotting scope. Counts were made from vantage points removed from the immediate study area to avoid disturbance. Each field was therefore counted on 60 occasions during the 2-week flood period. These counts were averaged and multiplied by the number of flood days to generate total crane use-days on each field for the entire flood period. To adjust for varying field sizes, total crane use days were divided by the number of field hectares to generate crane density per hectare for each field. Data Analysis Differences in sandhill crane use days among treatments were determined using a randomized block design. A repeated-measures ANOVA with treatment as the main plot factor and year as the repeated-measures factor weas used in these analyses. Treatment comparisons required Tukey s test for nonadditivity (Tukey 1949) which was used to test for block by treatment interaction. Sphericity was assessed using Kirk s Three-step Testing Strategy (Kirk 1982). Fisher s Least Significant Difference was used as a mean separation test (Milliken and Johnson 1992). Significance was determined at the α < 0.10 level for all tests. Multiple regression was used to explore the relationship between average crane use days per hectare as the dependent variable and seed, tuber, and rhizome mass (g/m 2 ) as explanatory variables on each field. Aboveground food resource explanatory variables included chufa, bearded sprangletop, barnyard grass, yellow bristlegrass, Eriochloa spp., Johnson grass, and fall panicum seeds. Belowground food resource explanatory variables included chufa tuber mass, and Johnson grass and field bindweed rhizome mass and 1997 data were combined in this analysis and significance was determined at the α < 0.10 level. RESULTS Sphericity was satisfied for sandhill crane use days in the treatment comparison. A treatment by year interaction occurred for sandhill crane use days (F 2,8 = 2.73, P = 0.10). Log transformation was required to satisfy normality for within-year analyses rendering median values following back-transformation. There was no block by treatment interaction for within year analysis in 1996 (F 2,8 = 0.10, P = 0.76) or 1997 (F 2,8 = 0.001, P = 0.96). No statistical differences (F 2,8 = 2.67, P = 0.13) were recorded for sandhill crane use days of treated wetlands in 1996, however there were differences among treatments in 1997 (F 1,8 = 3.08, P = 0.10). In 1997, crane use was higher

19 Proc. North Am. Crane Workshop 9:2005 CRANE USE OF CHUFA WETLANDS Taylor and Smith 169 Table 1. Median sandhill cranes per hectare on mowed, disced, and sustained flood treatments at the Bosque del Apache National Wildlife Refuge, New Mexico during winter (December, January, and February) and Treatment Median Confidence Interval (+) Year Mowed a 1 A abB 2.2 Disked aA aB 1.5 Sustained Flood aA bB Treatment medians followed by the same lower case letter are not different (P > 0.10). 2 Year medians followed by the same upper case letter are not different (P > 0.10). on disced fields than on sustained flood fields but crane use on mowed fields did not differ from either of these treatments (Table 1). Although not statistically significant in 1996, crane use of wetlands was also lowest in the sustained flood treatment. Chufa tuber mass and fall panicum seed explained 52.4% (R 2 = 0.52, P < 0.001) of the variation in sandhill crane use days on all fields in 1996 and 1997 (Table 2). Other explanatory variables including Johnson grass (partial r 2 = 0.1, P = 0.88), bearded sprangletop (partial r 2 = 0.3, P = 0.65), barnyard grass (partial r 2 = 4.2, P = 0.12), yellow bristlegrass (partial r 2 = 2.6, P = 0.16), Eriochloa spp. (partial r 2 = 0.06, P = 0.84), chufa (partial r 2 = 0.3, P = 0.62) seeds, and Johnson grass (partial r 2 = 2.7, P = 0.20) and field bindweed rhizomes (partial r 2 = 3.0, P = 0.33), were not statistically related to sandhill crane use days. DISCUSSION Although sandhill crane use did not differ among treatments in 1996, use did in Use closely mirrored differences found for chufa mass production where production was higher on disked fields than on sustained flood fields (also observed in 1996 by not statistically significant) but not different from mowed fields on either of these treatments (Taylor and Smith 2003). Cranes used fields with the most chufa mass and may have been especially attracted to disked fields in 1997 as chufa mass doubled from production levels recorded in Disking may therefore be an effective management practice for enhancing chufa production in managed wetlands for cranes. Although not statistically discernable from the mowed treatment, individual chufa tuber mass (g/tuber) was also highest in the disked treatment. The high individual chufa tuber mass recorded on disked fields indicated fewer, but larger tubers were available compared with other treatments (Taylor and Smith 2003). Tactile cues employed by cranes while probing subsurface areas are the most probable means of locating potential foods such as chufa tubers. Larger tubers in the disked treat- Table 2. Significant (P > 0.10) regression model variables explaining sandhill crane use on 30 moist-soil managed wetlands in 1996 and 1997 on the Bosque del Apache National Wildlife Refuge, New Mexico. Dependent n Independent Partial r 2 P > F Variable Variable (x 100) Sandhill cranes/ha 30 chufa tuber mass (g/m 2 ) Sandhill cranes/ha 30 fall panicum seed (g/m 2 )

20 170 CRANE USE OF CHUFA WETLANDS Taylor and Smith Proc. North Am. Crane Workshop 9:2005 ment might therefore provide a more detectable food item for meeting required daily caloric intake for sandhill cranes until foraging efficiency thresholds declined (Fredrickson and Drobney 1979). The strong relationship found between sandhill crane use and chufa production on treatment fields in this study supports the importance of this food item in the diets of cranes found by earlier researchers (Guthery 1976, Hunt and Slack 1987, Walker and Schemnitz 1987). In this study, chufa was the most important food item affecting crane use. It is unlikely that sandhill cranes would effectively forage on the small seeds produced by fall panicum, however the relationship between cranes and this annual graminoid may indicate use of plant parts other than its seed. Corms, the enlarged fleshy base of graminoid stems, have been cited as important summer food items for sandhill cranes in Idaho (Mullins and Bizeau 1978). Hitchcock (1971) reported at least one species of this Panicum genus as possessing a thick corm base. Lack of statisitical significance for barnyard grass and yellow bristlegrass may also be misleading due to small sample sizes. Probability values for these species were nearly significant and corms for these species may also be important dietary items. Questions, regarding the utilization of energetically important corms by sandhill cranes on wintering areas requires further research. The Rocky Mountain population (RMP) of greater sandhill cranes occupies arid irrigated valleys and basins across their winter range in the southwestern United States and the Mexican Interior Highlands (Drewien and Bizeau 1974). Recent wetland habitat loss due to groundwater mining and prolonged drought within portions of this range (J. Taylor, personal observation) is of concern to managers and biologists with management responsibilities for the population. In this study, over 48,000 sandhill crane use days were recorded on just 56 ha of managed wetland habitat. These wetland fields were converted from flood irrigated agriculture at nominal cost and managed to provide natural moist-soil vegetation for migratory birds (Fredrickson and Taylor 1982). Historically, water use for moist-soil vegetation production was comparable to agricultural crops (Taylor 2000) but overall water use has been reduced annually since 1998 without compromising wetland vegetation production (Bosque del Apache National Wildlife Refuge, unpublished data). More intensive moist-soil management on small converted agricultural fields across the arid Southwest could therefore provide important wetland food resources for the RMP sandhill population in the face of ongoing habitat loss and drought. ACKNOWLEDGMENTS We thank L. Brown, R. DelloRusso, M. Gallager, B. Hayes, D. Hawksworth, J. Kneuner, C. Lee, M. Oldham, and S. Scolari for their field assistance. L. M. Smith was supported by the Caesar Kleberg Foundation for Wildlife Conservation. This is manuscript T of the College of Agricultural Sciences and Natural Resources, Texas Tech University. We thank D. Johnson and R. Drewien for helpful comments on the manuscript. LITERATURE CITED Addy, E. O., and E. Eteshola Nutitive value of a mix ture of tigernut tubers (Cyperus esculentus L.) and baobab seeds (Adansonia digitata L.). Journal of Science Food Agriculture 35: Brown, D. E Biotic communities of the American Southwest: United States and Mexico. Desert Plants 4:3-341., and C. H. Lowe Biotic communities of the Southwest. U. S. Forest Service, Rocky Mountain Forest and Range Experiment Station, Albuquerque, New Mexico. General Technical Report RM-78. Drewien, R. C., and E. G. Bizeau Status and distribution of greater sandhill cranes in the Rocky Mountains. Journal of Wildlife Management 38: Fredrickson, L. H., and R. D. Drobney Habitat utilization by postbreeding waterfowl. Pages in T. A. Bookhout, editor. Waterfowl and wetlands-an integrated review. North Central Section of the Wildlife Society, Madison, Wisconsin, USA., L. H., and F. A. Reid Nutritional values of waterfowl foods in Managing waterfowl habitats: breed ing, migration, wintering. United States Fish and Wildlife Service-Office of Information Transfer, Fort Collins, Colorado, USA., and T. S. Taylor Management of seasonally flooded impoundments for wildlife. United States Department of the Interior, Fish and Wildlife Service. Resource Publication 148. Guthery, F. S Foods and feeding habitat of sandhill cranes in Southern Texas. Pages in J. C. Lewis, editor Proceedings of the International Crane Workshop. Hitchcock, A. S Manual of grasses of the United States. Dover Publications, Incorporated, New York, New York, USA. Hunt, H. E., and R. D. Slack Winter foods of the whooping crane based on stomach content analyses. Pages in J. C. Lewis, editor. Proceedings of the 1985 Workshop. Platte River Whooping Crane Habitat Maintenance Trust and United States Fish and Wildlife Service, Grand Island, Nebraska, USA. Johnson, W. R Soil survey of Socorro County area, New Mexico. United States Department of Agriculture, Soil Conservation Service, Albuquerque, New Mexico, USA. Jordan-Molero, J. E., and E. W. Stoller Seasonal de-

21 Proc. North Am. Crane Workshop 9:2005 CRANE USE OF CHUFA WETLANDS Taylor and Smith 171 velopment of yellow and purple nutsedges (Cyperus esculentus and C. rotundus) in Illinois. Weed Science 26: Keeley, P. E., and R. J. Thullen Light requirements of yellow nutsedge (Cyperus esculentus) and light interception by crops. Weed Science 26: Kelley, J. R Management and biomass production of selected moist-soil plants. Thesis. University of Missouri, Columbia, Missouri, USA., and L. H. Fredrickson Chufa biology and management in Managing waterfowl habitats: breeding, migration, wintering. United States Fish and Wildlife Service, Office of Information Transfer, Fort Collins, Colorado, USA. Kendeigh, S. C., Dol Nik, V. R., and V. M. Gavrilov Avian energetics. Pages in J. Pinowski and S.C. Kendeigh, editors. Granivorous birds in ecosystems. Cambridge University Press, Cambridge, United Kingdom. Kirk, R Experimental design procedures for behavior sciences, 2nd edition. Brooks/Cole Publishing Company, Belmont, California, USA. Knaur, D. F Moist soil plant production on Mingo NWR. Thesis. University of Missouri, Columbia, Missouri, USA. Krapu, G. L., G. C. Iverson, K. J. Reinecke, and C. M. Boise Fat deposition and usage by arctic-nesting sandhill cranes during spring. Auk 102: , and D. H. Johnson Conditioning of sandhill cranes during fall migration. Journal of Wildlife Management 54: Matthiesen, R. L., and E. W. Stoller Tuber composition in yellow nutsedge (Cyperus esculentus (L.)) variants. Weed Research 18: Merrell, J. L The effects of flooding on chufa (Cyperus esculentus L.). Thesis. Louisiana State University, Baton Rouge, Louisiana, USA. Milliken, G. A., and D. E. Johnson Analysis of messy data volume 1: designed experiments. Chapman and Hall, New York, New York, USA. Mullins, W. H., and E. G. Bizeau Summer foods of sandhill cranes in Idaho. Auk 95: Patterson, D. T Shading responses of purple and yellow nutsedge (Cyperus rotundus and C. esculentus). Weed Science 30: Reinecke, K. J., and G. L. Krapu Feeding ecology of sandhill cranes during spring migration in Nebraska. Journal of Wildlife Management 50: Sanchez Tames, R., and E. Vieitez Estudios sobre la brotadura de tuberculos de Cyperus esculentus aureus. Anales de Edafologia y Agrobiologia 29: Tacha, T. C., and P. A. Vohs Time and energy budgets of sandhill cranes from mid-continental North America. Journal of Wildlife Management 51: Taylor, J. P Chufa (Cyperus esculentus) management and use by migratory birds in the Middle Rio Grande Valley, New Mexico. Thesis, Texas Tech University, Lubbock, Texas, USA., and L. M. Smith Chufa management in the Middle Rio Grande Valley, New Mexico. Wildlife Society Bulletin 31: Taylorson, R. B Seasonal variation in sprouting and available carbohydrate in yellow nutsedge tubers. Weeds 15: Thullen, R. J., and P. E. Keeley Yellow nutsedge sprouting and resprouting potential. Weed Science 23: Thumbleson, M. E., and T. Kommedahl Factors affecting dormancy in tubers of Cyperus esculentus. Botanical Gazette 123: Tukey, J. W One degree of freedom for nonadditivity. Biometrics 5: Walker, D. L., and S. D. Schemnitz Food habits of sandhill cranes in relation to agriculture in central and southwestern New Mexico. Pages in J.C. Lewis, editor. Proceedings of the 1985 Workshop. Platte River Whooping Crane Habitat Maintenance Trust and United States Fish and Wildlife Service, Grand Island, Nebraska, USA. Wills, G. D Effect of light and temperature on growth of purple nutsedge. Weed Science 23:93-96.

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23 NEW LOCATIONS AND RANGE EXTENSION OF WINTERING SANDHILL CRANES IN CENTRAL NORTHERN MEXICO FELIPE CHAVEZ-RAMIREZ, Platte River Whooping Crane Maintenance Trust, 6611 W. Whooping Crane Dr., Wood River, NE 68883, USA Abstract: The overall distribution of wintering sandhill cranes in Mexico has been reported and summarized in several prior documents. However, most reports are associated with counts or surveys primarily conducted for wintering waterfowl. Recent ( ) reports compiled from local researchers show, that wintering sandhill cranes are distributed much more widely in northern Mexico than is currently reported in the literature. The new locations reported here are primarily in the eastern portion of the Mexican Altiplano, in the states of Coahuila and Nuevo Leon, and in the southern portions of the Chihuahuan Desert Region in Zacatecas and San Luis Potosi. Most locations are natural playas and ponds and man-made reservoirs. While cranes are clearly present in the areas reported here, the actual importance of each specific site as a wintering site or occasional stopover site requires further study. Key words: Sandhill crane, Grus canadensis, Mexico, distribution, wintering PROCEEDINGS NORTH AMERICAN CRANE WORKSHOP 9: The overall distribution of wintering sandhill cranes (Grus canadensis) in Mexico has been previously reported (Tacha et al Tacha et al. 1994, Meine and Arhcibald 1996). However, the distribution of wintering cranes defined in previous publications, are based on information gathered during the mid-winter waterfowl surveys (Buller 1982, Drewien et al. 1996). The midwinter waterfowl surveys have been conducted in Mexico by the US Fish and Wildlife Service since 1948 (Saunders and Saunders 1981). These surveys, plus other studies, have clearly identified several areas and specific sites as important wintering areas for sandhill cranes because of the significant number of cranes present during some years. Buller (1982) summarized crane counts obtained as part of wintering waterfowl surveys between 1959 and Later, Drewien et al. (1996) presented a more comprehensive summary spanning from 1959 through 1994 with more detail on numbers of cranes present in different sites in different years. The number of sites supporting cranes varies by year, as does the number of cranes present in a specific area in different years (Drewien et al. 1996). This is likely a result of many of the wetlands expanding and shrinking and even drying up completely during some winters. While some known wintering sites for cranes are well documented and surveyed regularly, it is done so because they are important wintering sites for migratory waterfowl. This strategy by necessity eliminates areas that are not important waterfowl wintering sites but could support cranes. Even though there appears to be considerable overlap in wintering sites between waterfowl and cranes, this is not always the case, as cranes are more likely to use smaller bodies of water. In addition, many sites used by waterfowl, particularly man-made reservoirs are, not always suitable for cranes because of their depth. Several publications (Tacha et al. 1992, Tacha et al. 1994, Meine and Archibald 1996) present the wintering distribution of sandhill cranes for northern Mexico (Fig. 1). The winter distribution, reported in comprehensive publications on cranes (Johnsgard 1983, Meine and Archibald 1996) or specifically sandhill cranes (Buller 1982, Tacha et al. 1992, Tacha et al. 1994, Drewien et al. 1996,), or birds of Mexico (Howell and Webb 1995) do not adequately reflect the current knowledge regarding presence of cranes within northern Mexico. The winter distribution maps available in the above mentioned publications show no wintering range extending into the states of Coahuila, Nuevo Leon, and San Luis Potosi (Fig. 1), despite there being regular sightings of significant numbers of cranes during winter in some wetlands in those states. Recent reports received via personal communications suggest that sandhill cranes are distributed much more widely in northern Mexico than is currently reported in published literature. This new information, available at present, can be used to expand the known distribution maps of wintering cranes in Northern Mexico. This better delineation of the wintering distribution of sandhill cranes in Mexico may prove valuable as the country develops its national wildfowl conservation plan (A. Lafon, pers. comm.). Mexico joined the North American Waterfowl Management Plan in 1994 (USDI, 1994), however, it has not been until recently that specific country based surveys within a national wildfowl conservation framework (A. Lafon pers. comm., Perez et al. 2005), have been planned. In order for Mexico to develop appropriate management and conservation actions it is important that updated and detailed information be available for planning and setting research and conservation priorities. Here I present a compilation of reports and sighting of cranes recorded between 1997 and 2002 intended to update the known winter distribution of sandhill cranes in northern Mexico. Most information reported here is from areas and locations where cranes have not been previously reported in the literature; however, a few locations have been noted previously. Most sighting and reports were collected by local researchers and reported to me and are presented here in an effort to further refine and better characterize the wintering distribution of sand- 173

24 174 SANDHILL CRANES IN NORTHERN MEXICO Chavez-Ramirez Proc. North Am. Crane Workshop 9:2005 A B C D Fig. 1. Winter distribution maps of sandhill cranes showing northern Mexico range from comprehensive treatments of sandhill cranes; A) modified from Tacha et al. 1992, B) modified from Tacha et al. 1994, C) modified from Meine and Archibald 1996, D) inset shows approximate area of northern Mexico covered by three previous maps. hill cranes in northern Mexico. METHODS I requested and collected information from individuals, who spend time in the field, in the states of Chihuahua, Durango, Coahuila, Nuevo Leon, Zacatecas, and San Luis Potosi. Many had sightings in their field notes from specific localities, while others promised to keep track of sightings in any upcoming trips to potential sites (wetlands). I limited the time span of observations to the years after In addition to direct field observations, I reviewed the important bird areas data base maintained by CONABIO (the Mexican National Commission for Biodiversity: and reviewed the lists of birds reported for each site. I only reviewed, and present, information for sites not well documented in the existing and available literature as wintering sites for cranes. Some sites considered important bird areas in the CONABIO data base overlapped with many sites reported directly to me by field biologists. While there are numerous locations where cranes have been observed, the data presented here are only for those areas that met at least one of the following characteristics: a) greater than 100 cranes were present during a single sighting, and/or, b) repeated observation in the same location of at least 10 cranes within the same winter, and/or c) repeated observations of crane groups in different years. In addition, only those sites that are new and have not been previously reported or described in detail in Buller (1981) or Drewien et al. (1996) are described here. A brief description and general location is given for those sites fitting the above criteria. Specific information for each site was obtained from published literature, CONABIO s important bird areas data base and/or from the field biologists themselves and personal observations. Other observations that do not fit the above criteria where taken into consideration to better delineate the extension to the wintering distribution range map presented here.