YUKON DELTA ALASKA HELICOPTER/FIXED WING COMPARATIVE WATERFOWL BREEDING POPULATION SURVEY. Progress Report III

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1 YUKON DELTA ALASKA HELICOPTER/FIXED WING COMPARATIVE WATERFOWL BREEDING POPULATION SURVEY Progress Report III Bruce Conant Migratory Bird Management - Juneau, Alaska Christian P. Dau Izembek National Wildlife Refuge - Cold Bay, Alaska William. Larned, Kenai National Wildlife Refuge - Soldotna, Alaska 696.A 52 C July 1991

2 TITLE: AREA: DATES: DATA SUPPLIED BY: Helicopter/Fixed Wing Comparative Waterfowl Breeding Population Survey Yukon Delta, Alaska (Stratum 09) June 3-7, 1991 Bruce Conant U.S. Fish and Wildlife Service, Juneau, Alaska Christian P. Dau U.S. Fish and Wildlife Service, Cold Bay, Alaska William Larned U.S. Fish and Wildlife Service, Kenai, Alaska ABSTRACT A comparative helicopter/fixed wing waterfowl breeding population survey was conducted on a 80 square mile sample of tundra habitat on the Yukon Delta in Alaska in early June of This was the third year of a planned three year study, a companion to the three year boreal forest study ( ). Standard procedures were used. Visibility correction factors calculated from indicated total birds by species for this year are compared with those from the last two years on the Yukon Delta, those developed on the Yukon Flats, and the standard rates used in the past. Continuation of the comparative survey program is recommended on an annual basis for both boreal forest and tundra habitats. INTRODUCTION Standard waterfowl breeding population surveys have been flown in Alaska for over 30 years (Conant and Dau 1991). The numbers of ducks recorded on these surveys have been expanded by a standard set of visibility correction factors derived from surveys conducted in prairie habitat. The applicability of these standard correction factors has not been thoroughly tested for "bush" habitat in general or for Alaskan habitats in particular. Previous work has shown the practicality of obtaining waterfowl counts from helicopters which compare closely to those obtained with ground counts (USFWS 1974, 1975, 1976; Haddock and Evans 1970, 1971, 1972; Ross 1985). In 1985 an experimental helicopter/flxed wing comparison survey was conducted on the Kaiyuh Flats in Alaska (Conant et al 1985). Because of the encouraging results of that effort, a more comprehensive study was initiated on the Yukon Flats (Conant et al 1986). A three year study was completed on the Yukon Flats in 1988 (Conant et al 1988). This year was the third year of a planned three year survey program to evaluate correction factors for Alaskan tundra habitat. This report gives the preliminary results of six years of work and provides recommendations for continuing the program. 1

3 ACKNOWLEDGEMENTS Tom Ratledge skillfully piloted the helicopter for a second year which made for a safe and efficient rotor wing survey. Ron Perry, refuge manager of the Yukon Delta National Wildlife Refuge, supported the comparative survey program and provided housing for both survey crews. Bob Delaney, Mike Hedrick, Dan Doshier, and Paul Schmidt foresaw the value of such a cooperative waterfowl project/refuge study and supported the participation of Bill Larned. Bob Leedy and John Sarvis provided needed support from the regional office. Bill Larned and Office of Aircraft Services personnel set up the helicopter charter contract. STUDY AREA The Yukon Delta was selected for comparative aerial surveys for tundra habitat in Alaska (Figure 1). It is a large (approximately 26,000 square miles), representative area of duck nesting habitat in tundra habitat. Logistics were manageable on this area. A major national wildlife refuge is located there. Standard waterfowl breeding population surveys have been flown over it for more than 30 years. Yukon Delta 0') (0... N N LO 0 0 LO LO 1""' M M Approximate Tree line Figure 1. Alaska-Yukon Waterfowl Breeding Population Survey strata including Yukon Delta (stratum 9) study area. 2

4 The standard Alaska-Yukon Waterfowl Breeding Population Survey design was used for both the helicopter and fixed wing surveys. A subset of the standard survey was selected with 3 transects containing 20 segments, each 16 miles in length and 114 mile in width, located generally perpendicular to the coast (Figure 2). A Yukon Delta NWR policy restricting helicopter use within 15 miles of the coast negated including coastal segments. All segments were flown which resulted in a comparative sample of 80 square miles for _f I X I I I I ' i.-.\ / ~.. ~ o i\ ' 0.Q I --.;,;. l.u Tl : /''" "-- "("":. I I I Figure 2. Locations of standard aerial transects and segments, from Alaska-Yukon Waterfowl Breeding Population Survey design, on Yukon Delta, Alaska study area. 3

5 EQUIPMENT The specially modified turbine beaver (N-754), which has been flown on standard Alaska-Yukon duck surveys for 15 successive years, was used for all six years of the fixed wing survey. A Bell Jet Ranger B-206/3 helicopter was used for all six years of the rotor wing survey. All observations were recorded i.."lto dic+..aphone Travel Master II tape recorders and transcribed directly into IBM compatible lap top computers in the field. PERSONNEL Fixed Wing: Again in 1991 the fixed wing crew was comprised of Bruce Conant, who piloted the fixed wing aircraft and made all left side observations, and Chris Dau, an experienced waterfowl biologist, who made all the right side observations. Helicopter: Bill Larned and Tom Ratledge were the helicopter survey team again in Bill Larned recorded all observations and aided all the helicopter pilots with the precise navigation for all six years of this project. METHODS All transects and segments were delineated on 2 sets of U.S. Geological Survey (USGS) 1:63,360 (1 inch = 1 mile) scale maps (Figure 3). These maps were used for precise navigation for both fixed wing and helicopter surveys. General orientation was maintained with USGS 1:250,000 (1 inch = 4 miles) scale maps. Data were recorded by 4 mile sub-segment increments for all six years of surveys. Fixed Wing: The fixed wing crew used standard survey techniques (USDI-CDE 1987) with the exception of using the larger scale maps for navigation. The centerline was followed at approximately 96 mph and at an altitude of feet above the ground. Both observers tallied waterfowl from front seats, by species, within the standard 1/4 mile (118 mile each side) transect width. The pilot handled all piloting, navigation, and made all observations on the left side of the aircraft in the standard way. The fixed wing survey was flown on June 2-6 as part of the standard survey and required 15 hours to complete out of Bethel. Helicopter: The helicopter crew followed standard survey guidelines (USDI-CDE supplement 1987). The pilot flew the helicopter from the right front seat. The observer helped with navigation and made all bird observations from the left front seat. The helicopter followed the centerline at about 50 mph and 100 feet above the ground until wetlands were encountered. If the wetland was small, a close pass by the right side was made at mph and at feet above ground to allow the observer a good view of the whole wetland and its shoreline. For larger wetlands, the entire portion within the transect boundaries was circled to the left at mph a.'l.d feet above ground permitting a good view for the observer. The helicopter was generally maneuvered over the shoreline vegetation so that birds in the wetland perimeter would tend to flush towards the open water rather than into the vegetation. On complex segments with extensive water areas, a meandering flight path was used to cover all waterfowl habitat. Upland tundra habitat and all streams within the transect were searched for waterfowl. The rotor wing survey was conducted June 3-7 and required 31 hours to complete out of Bethel. The helicopter crew flew most of the survey from Bethel and the remainder from Saint Marys where fuel and 4

6 lodging were available. Extra fuel containers were carried along to extend the range and duration of flights and one fuel cache was utilized in Figure 3. Typical segment and sub-segment detail on field survey map used for navigation, showing centerline and transect width boundaries, for Yukon Delta, Alaska study area. 5

7 RESULTS Total observations are presented for individual species or groups by singles, pairs, and flocks for both the fixed wing and rotor wing surveys flown in 1991 (Table 1). An "indicated total" was calculated using standard procedures (USDI-CDE 1987) by species or group for comparison. Calculated visibility correction factors were derived by comparing indicated totals for the most numerous species. The last columns of Table 1 give correction factors derived from the three years of this study and the standard correction factors currently in use for "bush" habitat (USDI CDE 1987) for comparison. Table l. Helicopter/Fixed Wing Comparison Survey Results, Yukon Delta, Alaska for 1991 compared to the standard rates. Fixed Wing Ind. a Helicopter Ind. a Correction Factors b DUCKS Sng Prs Flks Total Sng Prs Flks Total Standard Mallard Wigeon G.W. Teal Shoveler Pintail Dabblers Canvasback Scaup c Goldeneye Bufflehead Divers..,.o.L'+O i Oldsquaw Seater Merganser Miscellaneous TOTAL DUCKS W.F. Goose Canada Goose Swans c Cranes c Grebes Artie Loon R.T. Loon C. Loon a Indicated Total = (Singles x 2) + (Pairs x 2) + Flocked. b Correction Factor = Helicopter Indicated Total/Fixed Wing Indicated Total from 75 sq. mi. sample in c Singles not doubled in the calulation of Indicated Total. 6

8 Calculated correction factors are given in Table 2 for the three years of the boreal forest (Yukon Flats) study as well as for three years of the tundra (Yukon Delta) study. Boreal forest and tundra averages are shown to compare with the standard factors developed from historical comparison surveys on the prairies. Table 2. Correction Factors developed in Alsaka ( ) from Helicopter/Fixed Wing Comparison Surveys for boreal forest and tundra habitats compared to the standard prairie rates. Boreal Forest Tundra (Yukon Flats) (Yukon Delta) Prairie Average Average Standard Mallard Wigeon G.W. Teal Shoveler Pintail Dabblers Canvasback 1.9 ' Scaup Ringneck Bufflehead Divers Oldsquaw Seaters l.o 1.2 L4 1.2 L3 Misc DUCKS OTHERS t W.F. Goose C. Goose Swans 1.0 l.l Cranes Grebes Artie Loon R.T. Loon C. Loon

9 DISCUSSION Helicopter surveys offer a pragmatic way to conduct a comparative survey over Alaskan waterfowl habitat in a reasonable time frame. Adequate samples were obtained at a reasonable cost (about $20,000 per year). Ground counts of this scale would not be practical for Alaska in terms of time or costs. Weather was fairly constant throughout the survey period with typical winds and within the limits set forth in the Standard Operating Procedures (USDI-CDE 1987). Visibility was good and the wind factor was not deemed significantly different between surveys. The single helicopter observer was very experienced in aerial waterfowl surveys. The combination of the skills of the observer and the helicopter pilot negated the need for a rear seat observer to obtain a complete count in all six years of the rotor wing surveys, per discussion in our experimental work (Conant et al 1985). All four fixed wing pilot/observers used have extensive aerial waterfowl survey experience. This combined with the increased visibility from the unique fixed wing aircraft could have resulted in lower than average calculated visibility rates than for other fixed wing aircraft or less experienced flight crews. The exchange of survey personnel in 1987 and broadened the sample of fixed wing observers used for comparison which is more representative of past operational surveys in Alaska and Canada. Visbility correction factors derived for cranes, loons, and possibly geese are believed to be low for the boreal forest based on the observed reactions of these species (Conant et al 1986, Conant et al 1985), and also the number of observations made were small. In 1988 the helicopter pilot made some observations of cranes away from the ponds where the observer's attention was focused. This probably accounted for the higher correction fact..or for that year. Perhaps t.l-tey are more representative for those species on the tundra. The comparative surveys have been conducted in 4 phenologically different years (1986 and 1989-slightly late, 1987-slightly early, 1988 and 1990-early, 1991-average). At least, some visibility rates remained fairly constant (green-winged teal, pintail, scaup) in spite of this factor. Others, such as scoters, where the fixed-wing crew recorded more than the helicopter crew in 1988 may have been affected. More analysis is needed to evaluate possible effects. Other comparative helicopter/fixed wing surveys were conducted in "bush" habitat in Canada in 1986, 1987, and 1988 (Cole and Dickson 1986, Cole et al 1987, Brazda 1987). A comparison of Alaskan and Canadian results was made (Hines et. al., 1989) and further analyses are needed. More studies are needed, similar to those conducted in Canada (Cole and Dickson 1986), comparing helicopter observations to those made by stationary ground crews to better interpret the results of helicopter surveys. 8

10 We are pleased with the results of the 3-year study on the Yukon Fiats and the 3 years of effort on the Yukon Delta. Sufficient numbers of several species were recorded by both fixed wing and rotor wing surveys for valid comparison. The relative consistency of some of the correction factors for all years of the study and compared to the standard set is encouraging. A cursory look at the data shows the following patterns have emerged from this study. YUKON FLATS (Boreal Forest): Based on these samples, the standard factors in use for wigeon, pintail, and scaup appear too high. If the con ection factors determined from this study are close to true values, the potential for over-estimating populations for these species is significant. YUKON DELTA (Tundra): With three years of data, it was somewhat surprising to find a general increase in some correction factors over those generated in boreal forest habitat (pintail, scaup). A fairly consistent pattern has developed in tundra visisbility rates for some species (mallards, shovelers, pintails, scaup, oldsquaw, scoters, Canada geese, cranes, arctic loons). More data would help to substantiate this consistency. Again, the close similarity between swan observations (144 versus 162) supports the conclusion that both surveys were basically counting birds within the same transect area. Perhaps single geese, grebes, and loons should not be doubled in developing the "indicated totals" for the helicopter surveys on the tundra. RECOMMENDATIONS 1. Use the average visibility correction factors developed in Alaska over the last six years for the major species in piace of the current "standard factors" for all fixed wing breeding population surveys in Alaska. Use either the boreal forest or tundra factors as appropriate. 2. Evaluate other types of survey aircraft (Cessna 185, 206) to try to detect if there is any equipment factor. 3. Use average continental correction factors for the species with insufficient data for Alaskan correction factors. 4. Consider conducting annual fixed wing/helicopter comparison surveys for both boreal forest and tundra habitats and implementing a system similar to the continental program for the developement of "crew specific" correction factors each year. 5. Analyse the six years of data from this study in more detail, by 4 mile segment and produce a summary publication. 9

11 REFERENCES Brazda, A.R Helicopter/Fixed Wing Comparative Waterfowl Breeding Population Survey- May USFWS Field Report. Lafayette, Louisiana. Cole, R. W. and K.M. Dickson A Progress Report on Helicopter Surveys of Ducks /During the Breeding Pair Survey, Northwest Territories CWS Progress report. Yellowknife, Northwest Territories. Cole, R.W., A. Brazda, B. Conant, and J. Goldsberry Visiblity Rate Study of Boreal Forest Ducks. CWS-USFWS Progress Report. Yellowknife, Northwest Territories. Conant, B. and C.P. Dau Alaska-Yukon Waterfowl Breeding Population Survey. Processed USFWS report. Juneau, Alaska. 26pp. Conant, B., J.l. Hodges, W. Larned, and L.S. McLean Yukon Flats Helicopter/Fixed Wing Comparative Waterfowl Breeding Population Survey. Progress Report Ill. Processed USFWS report. Juneau, Alaska. 10pp. Conant, B., F. Roetker, W. Larned, and L.S. McLean Yukon Flats Helicopter/Fixed Wing Comparative Waterfowl Breeding Population Survey. Progress Report II. Processed USFWS report. Juneau, Alaska. 9pp. Conant, B., J.l. Hodges, W. Larned, and L.S. McLean Yukon Flats Helicopter/Fixed Wing Comparative Waterfowl Breeding Population Survey, Progress Report I. Processed USFWS report. Juneau, Alaska. 8pp. Conant, B., J.l. Hodges, P. Feiger, and M. Smith Experimental Helicopter vs. Fixed Wing Waterfowl Breeding Population Survey. Processed USFWS report. Juneau, Alaska. 7pp. Conant, B., J.G. King, and H.A. Hansen Sandhill Cranes in Alaska- A Population Survey 1957: American Birds 39(5): Haddock, J.L. and C.'D. Evans. Spring Bird Populations on Alaska's Arctic slope. Unpublished USFWS report. 'Anchorage, Alaska. Hines, J.E., R.W. Cole, A. Brazda, B. Conant, and J. Goldsberry Correcting for Visibility Biases in Aerial Surveys of Boreal Forest Ducks. CWS-USFWS Final Progress Report. Yellowknife, Northwest Territories. 15 pp. King, J.G Evaluating Alaska Habitats for Ducks. Processed USFWS report. Juneau, Alaska. 3pp. 10

12 Ross, R.K Helicopter vs. Ground Surveys of Waterfowl in the Boreal Forest. Wildlife Soc. Bull. 13(2): U.S. Department of the Interior/U.S. Fish and Wildlife Service and Canadian Department of the Environment/Canadian Wildlife Service Standard Operating Procedures for Aerial Waterfowl Breeding Ground Population and Habitat Surveys. Unpublished Manual. U.S. Department of the Interior/U.S. Fish and Wildlife Service and Canadian Department of the Environment/Canadian Wildlife Service Standard Operating Procedures for Helicopter Surveys to Assess Visibility Bias in Fixed-Wing Surveys of Boreal Forest Ducks -A Supplement to the S.O.P. for the Waterfowl Breeding Ground Population and Habitat Survey- April U.S. Fish and Wildlife Service. 1974, 1975, Office of Migratory Bird Management. Unpublished reports. Laurel, Maryland. 11