Warner Wetlands / Warner Valley BCS number: 48-31

Transcription

1 Oregon Coordinated Aquatic Bird Monitoring: Description of Important Aquatic Bird Site Warner Wetlands / Warner Valley BCS number: Site description author(s) Vernon Stofleth, Lakeview BLM District Kate Halstead, Field Technician, Klamath Bird Observatory Primary contact for this site Vernon Stofleth, Lakeview BLM District Site location (UTM) Zone: 11, Easting: , Northing: Boundaries and ownership Boundaries: Warner Valley runs from Greaser Reservoir (Adel, Oregon) at the south end to Bluejoint Lake (Plush, Oregon) at the north end. Ownership: The 52,033 acre Area of Critical Environmental Concern (ACEC) is almost entirely public Bureau of Land Management (BLM)-administered land (51,045 acres BLM and 988 acres of private and Oregon Department of State lands) and is surrounded by public land (United States Fish and Wildlife Service (USFWS) Hart Mountain Refuge on the East and BLM on the West). The private lands are located at the south end and northwestern end of the ACEC. See Figure 1 for BLM Lakeview District ownership map. Water levels The Bureau of Land Management possesses 13,000 acres of appropriated water rights for the Warner Wetlands Area of Critical Environmental Concern. Warner Wetlands is dependent upon Hart Lake water levels. If Hart Lake is spilling naturally, water can be diverted into the wetlands after March 1, which is the irrigation season and units are flooded with 3 to 36 of water each spring. If Hart Lake does not spill, water can be accessed by the Hart Lake irrigation pump during irrigation season. The Warner Wetland dries up completely every 8-10 years when Hart Lake dries up. The irrigation water in the Warner Wetlands lasts until July or August each year that it is used for irrigation. Evaporation is the largest contributing factor in water loss in the wetlands. Studies have shown that evaporation varies with temperature and wind speed (1/2 to 1 inch per day at the peak). Description updated 4/30/2010 1

2 Focal species use and timing Secretive marsh birds, colonial nesters, ground based aquatic birds, and migrating shorebirds can all be seen in the Warner Wetlands during April through August. Focal Guild/Species Wintering Breeding Migration Secretive Marsh Birds* Present Colonial Nesting Waterbirds Present Ground-based Aquatic Birds Present Migrating Shorebirds Present American White Pelican Barrow s Goldeneye Black-necked Stilt Bufflehead Dusky Canada Goose Franklin s Gull Greater Sandhill Crane Long-billed Curlew Snowy Egret Red-Necked Grebe Upland Sandpiper Western Snowy Plover Yellow Rail *The focal species for Oregon s aquatic secretive marsh bird monitoring are PBGR, LEBI, AMBI, VIRA, SORA, YERA. Species observed within the Warner Wetlands are: American White Pelican Black-necked Stilt Bufflehead Long-billed Curlew Pied-billed Grebe Sandhill Crane Snowy Egret Yellow Rail Description updated 4/30/2010 2

3 Location of Type 1 and 2 habitat within the site* Functional Group Type 1 Habitat Type 2 Habitat Ground Based Aquatic Perimeter of Lake Wet meadows Birds Secretive Marsh Birds Emergent Vegetation n/a Colonial Nesters Emergent Vegetation, open Perimeter of Lake water Migrating Shorebirds Shoreline Perimeter of Lake *See Figure 2 for USFWS National Wetlands Inventory (2008) layer in Google Earth (2008). The 51,045 acre ACEC is comprised of 18,569 acres of wetland habitat and 32,476 acres of upland habitat. Within the wetland habitat type there are 13,065 acres of Palustrine emergent, 600 acres of unconsolidated Palustrine, and 4,904 acres of open water Lacustrine habitat. The emergent habitat is comprised of Baltic rush, bulrush, cattails, and sedges. The Type 1 habitat is 18,569 acres of emergent Palustrine shoreline and the Type 2 habitat is 5,504 acres of unconsolidated bottom and open water habitat. Access to Type 1 and 2 habitat and visibility/audibility of birds There is good public land access (hiking, vehicle, and boat) to most of the area. The public/private fringe areas can be surveyed with a spotting scope or boat. During high water years, the lakes and channels can be accessed by motorboat. The area is large (18,569 acres) but contains mostly open water with very little emergent shoreline that either would not need to be surveyed or would be fairly easy to survey by boat. After 2 or 3 wet cycles the wetland vegetation grows up heavy and tall so visibility is limited especially in the southern quarter of the wetlands. Approximately 1 year in 10 the entire wetland dries up so surveys would not be needed. In the 52,033 acre ACEC area, access is limited to open roads and trails that are marked on the ground. This limits vehicular access, including ATV s, however does not limit boat access except amphibious vehicles that can be driven on land and water. Audibility is good on the entire area with the exception of the area just north of Hart Lake where all of the loud irrigation pumps are located. Vehicle use on County Road 3-12 is light. See Figure 3 for general road map of the area (Google Maps 2009). Past and current surveys Waterfowl brood counts have been conducted in the 1990 s and into the 2000 s with incidental sightings of secretive marsh birds noted. In 2008, KBO surveyed for six focal secretive marsh bird species (Pied-billed Grebe, American Bittern, Least Bittern, Yellow Rail, Sora, and Virginia Rail) during peak breeding season (May and June). Pied-billed Grebes, Sora, and Virginia Rail were found in abundance, and several American Bittern were also detected. Description updated 4/30/2010 3

4 Conservation issues Noxious weeds Wind Development Livestock Grazing Conservation measures taken, in progress, or proposed Ongoing noxious weed management Warner Wetland Area of Critical Environmental Concern Plan Warner Wetlands Allotment Management Plan Lakeview Resource Management Plan Potential survey methods a. Description: The lower fourth of the unit is best surveyed by 4WD vehicle and hiking. The upper three-fourths of the unit are best surveyed by boat since the area is too large to hike. Our waterfowl surveys usually begin in May but marsh bird surveys could possibly commence earlier. b. Selection Bias: It would be very difficult to survey the entire area due to the large size. With our limited time and personnel constraints, we conduct waterfowl brood trend counts on 3 or 4 areas of the Warner Wetlands and then extrapolate an estimate for the entire 18,569 acres of wetland. c. Measurement error and bias: Unless vegetation is removed completely by prescribed burning followed by flooding, the vegetation is too thick to get a complete count. We rely on professional judgment or WAG an estimate of percentage viewed with some certainty. Manning and Hartley (2006) suggest that a ground-based survey for all aquatic birds, a secretive marshbird survey, a migrating shorebird survey, and a survey of breeding colonies would be valuable. These surveys would probably need to be conducted by staff. Potential pilot studies Description updated 4/30/2010 4

5 Literature cited Bureau of Land Management, Lakeview District ownership map. Accessed October 10, Bureau of Land Management. Lakeview District. Accessed October 10, Google Earth version Image: Warner Wetlands, Oregon. Accessed October 10, Google Map Map of Warner Wetlands, Oregon. Accessed March 20, Manning, Ann and Laura Hartley. March Important sites for aquatic birds in Eastern Oregon. Version 2.0. U. S. Fish and Wildlife Service (USFWS) National Wetlands Inventory website. U. S. Department of the Interior, Fish and Wildlife Service, Washington, D.C. Accessed October 10, Description updated 4/30/2010 5

6 Figure 1: BLM Lakeview District ownership map. The red box indicates Warner Wetlands area. Description updated 4/30/2010 6

7 Figure 2: Google Earth (2008) map of Warner Wetlands with the USFWS National Wetlands Inventory (2008) layer. Description updated 4/30/2010 7

8 Figure 3: Google Map (2009) road view of Warner Wetlands. Description updated 4/30/2010 8

9 Description updated 4/30/2010 9