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GOLDEN EAGLES (Aquila Chrysaetos) NESTING IN OREGON, 2011–2018 Annual Report Frank B. Isaacs Oregon Eagle Foundation, Inc. 24178 Cardwell Hill Drive Philomath, OR 97370, USA 541-231-1674, [email protected] 20 February 2019 !1 GOLDEN EAGLES (Aquila chrysaetos) NESTING IN OREGON, 2011– 2018: Annual Report Suggested Citation: Isaacs, F. B. 2019. Golden eagles (Aquila chrysaetos) nesting in Oregon, 2011–2018: Annual Report, 20 February 2019. Oregon Eagle Foundation, Inc., Klamath Falls, Oregon, USA. POPULARIZED INTRODUCTION & SUMMARY The golden eagle (Aquila chrysaetos) is found throughout the Northern Hemisphere. In North America, it occurs from the arctic to central Mexico and is one of the largest North American raptors. In Oregon, golden eagles occur statewide and are most common in the eastern half of the state. Migrant golden eagles from other areas visit the state in the winter, while nesting pairs mostly appear to be year-round residents. Golden eagles take five years to attain full-adult plumage and can breed prior to that. Subadult golden eagles can stay close to their natal areas as they mature or may travel great distances from where they were hatched, or both. Non-breeding golden eagles from Oregon may visit surrounding states, and those from surrounding states may spend time in Oregon. There were no statewide research projects on golden eagles nesting in Oregon until this study. The project was initiated in 2011 because of concerns about the effects of energy development on the species. The goal of this work is to find as many golden eagle nests in the state as possible each nesting season (February through July) to document nest use and determine how many eaglets are raised each year. Over 60 organizations and 700 individuals, including citizen science volunteers have contributed to the project. Through 2018, 1,018 golden eagle nesting areas have been identified, 577 were reported before 2011, and 441 have been added since. Each year ~77% of nesting areas were observed; ~58% of the observed nesting areas were occupied; nesting outcome was determined at ~87% of occupied nesting areas; and ~59% of those with known outcome were successful. As a result of that effort, a total of 2,246 golden eaglets were counted from 2011–2018 in Oregon. The minimum golden eagle nesting population for Oregon was estimated at ~589 nesting pairs; and the minimum number of eaglets produced each year was estimated at ~486. 2019 will be the ninth consecutive year of what we hope will be a ten-year project that will end after the 2020 nesting season and provide a valuable description of the status of nesting golden eagles in Oregon at the beginning of the 21st century. !2 ABSTRACT The current list of 1,193 golden eagle nesting areas (NA) in Oregon consists of 577 reported before 2011 and confirmed during this study (48%), 441 first reported during 2011–2017 (37%), 124 reported prior to 2011 and searched but not confirmed (10%), and 51 reported before 2011 that have not been visited (4%). Additional undiscovered NAs likely exist in un-searched habitat throughout the state. Mean annual nesting results were 58% occupied (range 52%–62%), 59% successful (range 45%–71%), 0.81 young per occupied nesting area with known outcome (range 0.63–1.04), and 1.38 young per successful nesting attempt (range 1.28–1.46). Mean estimated minimum statewide nesting population was 589 nesting pairs (range 533–632), and mean estimated minimum production was 486 eaglets per year (range 346–619). NA occupation increased from 46% when observed one year (n = 78) to 94% when surveyed eight years (n = 240). Successful nesting at least once increased from 58% for NAs with one year of known outcome (n = 144) to 97% for NAs with eight years of known outcome (n = 36). Those data on occupation and nesting success show the value of multiple years of monitoring. Fifty-two percent of nests (n = 2,677) were on land managed by Bureau of Land Management, 30% were on private land, 10% were on U.S. Department of Agriculture land, 3% were on land managed by U.S. Fish and Wildlife Service, and 5% were divided among five other entities. Nests were built on cliffs (76%), in trees (22%), and on electricity pylons (2%, n = 995). Egg-laying and initiation of incubation began during the week of 29 January–4 February, peaked during 26 February–3 March and ended the week of 1–7 April (n = 478 estimated nesting chronologies). Egg-laying dates determined subsequent timing of incubation, hatching, and eaglet development, with the peak abundance of 8–10 week old eaglets occurring in mid-June. One-hundred-two eaglets were banded at 68 nesting areas and 10 were equipped with satellite transmitters during 2012–2014. One banded juvenile was captured near Prescott, Arizona and released unharmed, and one was electrocuted near its natal nest near Crane, Oregon. As of 25 February 2018, all ten radioed nestlings either died or had shed their transmitters after fledging. Continued inventory of listed NAs, additional searches of likely habitat, and continued monitoring of occupied NAs are recommended. !3 INTRODUCTION The golden eagle (Aquila chrysaetos) is distributed throughout the Northern Hemisphere, primarily between 20° and 70° N latitudes (Watson 1997:22). In North America, the species is most abundant west of 100° W longitude from the arctic slope to central Mexico (Kochert et al. 2002:3) and nesting occurs over a wide range of elevations in open and semi-open habitats (Kochert et al. 2002:7). Golden eagles have been observed throughout Oregon and nesting has been documented in all counties east of the Cascades and in 9 of 18 counties west of the Cascades (Carey 2003:161, Isaacs & Opp 1991, this study). Golden eagles are protected by the Migratory Bird Treaty Act in Canada, the U.S. and Mexico, and the Bald and Golden Eagle Protection Act in the U.S. (U.S. Fish and Wildlife Service 2009). In Oregon, golden eagles are designated as protected non-game wildlife by Oregon Department of Fish and Wildlife (2010). Suspected long-term population decline (Kochert et al. 2002:26) and recent resource development and related eagle mortalities resulted in concerns about the status and future of the species in the western U.S. (U.S. Fish and Wildlife Service 2010, Pagel et al. 2013). However, subsequent trend analysis indicated that golden eagles were not declining widely in that area (Millsap et al. 2013). The population of nesting golden eagles in Oregon was estimated at a minimum of 500 nesting pairs in the mid-1980s, however that estimate was based on limited and inconsistent monitoring and rough estimates of survey coverage (Isaacs & Opp 1991). In addition, statewide population trends could not be determined from those data because of inadequate monitoring (Isaacs & Opp 1991). Local studies within Oregon !4 correlated golden eagle nesting success with black-tailed jackrabbit (Lepus californicus) abundance during 1966–1980 in southeastern Oregon (Thompson et al. 1982), suggested population increase from 1972–1989 in Baker County, northeast Oregon (Larry Roumpf, Baker City, OR, personal communication), and suggested population decline in central Oregon from 1966–1984 (Anderson 1985). Despite those efforts, the size, distribution and productivity of the population of golden eagles nesting in Oregon had not been determined and statewide trends in those parameters were unknown. Current efforts by U.S. Fish and Wildlife Service (USFWS) to protect golden eagles and ensure no declines in breeding populations (Pagel et al. 2010:2) require baseline and trend information on size, distribution, and productivity. The objectives of this project are to determine those parameters for nesting golden eagles in Oregon. The goal is to provide baseline information required to determine long-term trends in the status of the golden eagle breeding population as was accomplished for peregrine falcons (Henny & Pagel 2003, Isaacs 2008) and bald eagles (Isaacs & Anthony 2011). This report contains results of golden eagle nest survey, inventory, and monitoring in Oregon through 2018. !5 ACKNOWLEDGEMENTS Without grants and cash contributions this project could not have been done. That funding, in descending order by amount contributed, has been provided by: U.S. Bureau of Land Management (BLM) Bonneville Power Administration (BPA) U.S. Fish and Wildlife Service (USFWS, Western Golden Eagle Team (WGET) Avangrid - Iberdrola Renewables USFWS - Region 1 - Oregon Fish and Wildlife Office Gary Landers EDPR North America Portland General Electric (PGE) Oregon Eagle Foundation, Inc. (OEF) American Wind Wildlife Institute (AWWI) American Wind Energy Association (AWEA) The Estate of Daniel Joseph Wadosky Orion Renewables RES America Developments, Inc. E.ON Climate & Renewables North America, Inc. Oregon Department of Fish and Wildlife Eurus Combine Hills II Invenergy U.S. Forest Service (USFS) Eurus Combine Hills I USFWS - Region 1 - Migratory Birds BP Wind Energy enXco Gray Family Foundation Anonymous Private Individual Bill Price Memorial Fund Ray Temple & Stephanie Hazen Hoffmann Family Fund Richard Hoyer Firstwind East Cascades Audubon Society (ECAS) Marilynne Keyser Oregon Parks and Recreation Department (Eagle Watch Sales) Gregory Stempien Lynn Sharp William Pearcy J.M. and L.E. Bousquet, Jr. Connie & Joseph Jones George Boehlert !6 Paul Miller & Kathy Cushman Friends of the Sisters Library (FOSL) David Anderson of Boise Idaho David Vick Camp Sherman Waste Transfer and Recycling Site Friends and Neighbors of the Deschutes Canyon Area (FANS) Rogue Valley Audubon Society Kevin Smith Salem Audubon Society (SAS) Grainger Hunt Lawrence Pearcy Kathryn Duman Ralph & Charlotte Opp, and Andrew & Katherine Passarelli. Special thanks to every cash contributor! Nest entry for banding, telemetry and contaminant research during 2012–2014 was funded by USFWS (Oregon Fish and Wildlife Office and Western Golden Eagle Team). Special thanks to the late Bill Price for managing OEF’s nest entries and to Carole Hallett, Eric Forsman, Jeremy Buck and David Leal (USFWS), David Anderson (The Peregrine Fund), Dan Varland (Coastal Raptors), Collin Eagles-Smith and Garth Herring (U.S.