South Puget Sound Streaked Horned Lark (Eremophila Alpestris Strigata) Genetic Rescue Study Report for Year 2
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South Puget Sound Streaked Horned Lark (Eremophila alpestris strigata) Genetic Rescue Study Report for Year 2 Spring/Summer 2012 Photo credit: Rod Gilbert South Puget Sound Streaked Horned Lark (Eremophila alpestris strigata) Genetic Rescue Study Draft Report for Year 2 September 2012 Prepared by Adrian Wolf THE CENTER FOR NATURAL LANDS MANAGEMENT The Center for Natural Lands Management 120 East Union Avenue, suite 215 Olympia, WA 98501 Tel. 360-742-8212 Email: [email protected] Abstract Hatchability of Streaked Horned Lark (Eremophila alpestris strigata) eggs in the Puget Lowlands of Washington State is extremely low relative to other grassland nesting birds at the same site and generally. Because genetic factors (inbreeding depression) appear to be a likely explanation, an effort to increase genetic diversity was initiated in 2011. 2012 was the second year of the genetic rescue effort initiated at the 13th Division Prairie on Joint Base Lewis-McChord. A total of eight breeding lark pairs and one unpaired male were detected within the study area. Nest building was first detected on 25 April; the first eggs were observed on 16 May; the first nestlings hatched on or around 27 May, the first fledgling was observed on 20 June. Twenty nests were located, which produced a total of 49 eggs (2.9 eggs/nest ± 0.9 SD). Mean number of eggs per completed clutch (n = 15) was 3.1 ± 0.6 (SD), an increase from 2.3 in 2011. A total of 14 local nestlings were color-banded, and at least four of the fourteen were observed foraging independently. Hatchability of the Puget Sound nests increased to 84% in 2012, from 61% in 2011. It is unknown what might account for the increase in vital rates in 2012. In 2012, no egg-clutches were translocated to Puget Sound nests from Corvallis, Oregon. This was due to significantly high nest failure at the Corvallis airport (floods and then mass predation) and the difficulty of matching egg-clutch incubation timing. Because of the low productivity of the Oregon airport population in the early- to mid-season, the egg swap effort was abandoned in mid-July. No banded birds that originated from Corvallis translocated clutches were observed at lark nesting sites outside of 13th Division Prairie (i.e., McChord Airfield, Gray Army Airfield, JBLM Range 76 of Artillery Impact Area, Olympia Airport, or Sanderson Airfield). In 2012, one Oregon translocated nestlings returned to 13th Division Prairie as an adult male, but this male did not breed successfully with a female in 2012. Assuming that the male survives its second winter, returns to 13th Division and successfully reproduces in 2013, the local population of Streaked Horned Lark could be rescued, which can lead to improved fitness and reduced extinction risk. Subsequent monitoring will determine whether the male or other translocated birds return to breed. Table of Contents Abstract .................................................................................................................................. 2 Introduction ............................................................................................................................ 1 Methods .................................................................................................................................. 1 Clutch Age Determination ............................................................................................. 1 Banding .......................................................................................................................... 2 Focus Banded Lark Surveys........................................................................................... 2 Results and Discussion ........................................................................................................... 4 Returning Birds .............................................................................................................. 5 Swapped Eggs ................................................................................................................ 5 Banded Bird Surveys ..................................................................................................... 5 Comparison between 2011, local and Oregon Streaked Horned Lark nests .................. 6 Noteworthy Species ....................................................................................................... 9 Conclusion ............................................................................................................................. 9 Management Recommendations ............................................................................................ 9 Future Plans .................................................................................................................... 9 Further Information Available ..................................................................................... 10 Bibliography ......................................................................................................................... 11 Acknowledgments ................................................................................................................ 13 List of Figures Figure 1: Location of Nest Monitoring Study Sites .............................................................. 3 Figure 2: Location of 13th Division Prairie relative to Banded Bird Survey Sites ................ 4 Figure 3: Streaked Horned Lark nests detected at 13th Division Prairie, 2011 to 2012. ....... 7 List of Tables Table 1: Comparing clutch size, hatch rate, fledglings per nest, and egg size between Puget Sound nests and translocated clutches from Corvallis Airport, 2011 and 2012. 6 Table 2: Streaked Horned Lark Nestling Banding Details, 13th Division Prairie, 2012. ...... 8 List of Appendices Appendix A: Summary of Streaked Horned Lark nests at 13th Division Prairie ................ 14 Appendix B: Banded Streaked Horned Lark Adults ........................................................... 15 Appendix C: Streaked Horned Lark Egg Measurements .................................................... 15 Appendix D: Birds detected at 13th Division Prairie, 2011 to 2012 ................................... 16 Appendix E: Noteworthy birds detected at 13th Division Prairie ........................................ 18 Appendix F: Common Nighthawk nestlings. ...................................................................... 18 Introduction The native prairies of Washington’s south Puget Sound area occupy less than 10% of their historical distribution (Crawford and Hall 1997). Explanations for the disappearance of these native grasslands include conversion to forestlands, agriculture and urban development. In addition, degradation and fragmentation of the grassland vegetation community by exotic species have further reduced the quality and extent of prairie ecosystems. Many wildlife species associated with prairies have also declined significantly, and several species are threatened with extinction and are candidates for federal listing under the Federal Endangered Species Act. One species associated with prairie-oak and other grassland habitats is the Streaked Horned Lark (Eremophila alpestris strigata), a ground-nesting passerine. The Streaked Horned Lark is a genetically distinct subspecies (one of 24 subspecies) of the Horned Lark that historically ranged from the Rogue and Willamette Valleys of Oregon, north to the Georgia Basin of British Columbia and coastal beaches in Washington (Drovetski et al.2005, Stinson 2005). The current distribution of breeding larks has been reduced to the Willamette Valley, dredged material islands of the Columbia River, coastal beaches of Washington, and South Puget Sound grasslands. For these reasons, the United States Fish and Wildlife Service determined that listing of the Streaked Horned Lark is warranted under the Federal Endangered Species Act (50 CFR part 17). The South Puget Sound population of Streaked Horned Lark is declining rapidly (Camfield et al. 2011, Camfield et al. 2010), and explanations for the recent decline include low adult and juvenile survival and low fecundity (Camfield et al. 2011, Camfield et al. 2010, Pearson and Hopey 2005). This study is the second year of a multiyear effort to reverse the decline of Puget Sound Streaked Horned Lark population by increasing genetic diversity. The rescue effort entailed translocating eggs to 13th Division Prairie from nests at a site in Corvallis, Oregon that was not exhibiting low egg hatchability. Surviving fledglings that breed at the new site should benefit the new population by increasing genetic diversity and improving hatchability. Methods The genetic rescue project was accomplished by locating and monitoring nests at the 13th Division Prairie, Joint Base Lewis-McChord, and at the Corvallis Municipal Airport in the Willamette Valley of Oregon (Fig. 1). Nest locating and monitoring methods were adapted from Martin and Geupel (1993). Female larks were located and then followed with spotting scope or binoculars for signs of nest building or nest tending activity. When conspicuous nest building activity was not observed, areas where female activity was concentrated were searched on foot. Clutch Age Determination Clutch age was, in most cases (n = 10), determined by discovering nests during the nest building or egg laying stage (1 egg is laid per day and incubation starts upon laying of 1 the penultimate egg in the clutch). When nests were discovered during the incubation stage (n = 5), clutch age was determined with