Range-wide Streaked Horned Lark (Eremophila alpestris strigata) Assessment and Preliminary Conservation Strategy

The Streaked Horned Lark (Eremophila alpestris strigata) is a rare subspecies of the Horned Lark that breeds and winters in Oregon and Washington. Recent Streaked Horned Lark research has focused on documenting changes in the subspecies breeding range (Rogers 2000), inventorying and locating current breeding (Altman 1999, Rogers 1999, MacLaren and Cummins 2000, Pearson and Hopey 2004, 2005) and wintering (Robinson and Moore unpubl., Pearson et al. 2005) populations in Oregon and Washington, identifying breeding and foraging habitat (Altman 1999, Rogers 2000, Pearson 2003, Pearson and Hopey 2004, 2005), and experimenting with methods to improve Lark habitat (Pearson and Hopey 2005). In addition, British Columbia recently completed a status report on the Lark (Beauchesne and Cooper 2003) and another has been drafted by Washington Department of Fish and Wildlife (Stinson 2005).

The goal of this report is not to duplicate the efforts of others but to provide a range-wide review of the current wintering and breeding range, list of habitat requirements and estimates of wintering and breeding population numbers. In addition, we identify population threats, recommendations for addressing these threats and we present a preliminary conservation strategy. Because others have attempted to reconstruct this subspecies historic wintering and breeding ranges and to describe its life history (Rogers 2000, Beauchesne and Cooper 2003, Stinson 2005), we spend little effort on these topics. The management recommendations and conservation strategy presented here are initial thoughts and need critical review, revision and development. If the subspecies is listed as Endangered in Washington as recommended, a recovery strategy will be developed for the State. Canada is currently writing a recovery plan. In addition to these efforts, we strongly recommend developing a range-wide conservation plan (including a metapopulation model) and establishing a range-wide (Oregon, Washington, British Columbia) working group to develop recovery strategies and facilitate recovery actions.

Several lines of evidence suggest that the Streaked Horned Lark is vulnerable to extinction and should be a conservation priority. The Streaked Horned Lark is a recognized subspecies of the Horned Lark (AOU 1957) and genetic data indicate that the Streaked Horned Lark is unique, isolated, and has little genetic diversity (Drovetski et al. in press). The breeding range of the Lark has contracted over time; it no longer breeds in the northern Puget trough (San Juan Islands and other Puget Sound sites north of Tacoma), southern British Columbia, along the Washington Coast north of Grays Harbor, and in the Rogue River Valley (Rogers 2000, Beauchesne and Cooper 2003, Stinson 2005). Although no systematic range-wide attempt has been made to estimate the total population of this subspecies, results from winter and breeding surveys suggest that the entire population of this subspecies is likely less than 1,000 birds (see discussion below). Remaining breeding populations and their habitats face imminent threats posed by land development, incompatible land uses, human activities, predation, and non-native species. Wintering populations are potentially threatened by stochastic events and by a lack of suitable habitat in the Willamette Valley. Very few of the sites used by the Lark for breeding or wintering are protected and no sites are managed primarily for Larks.

Conservation efforts to date, have focused on identifying and monitoring Lark populations, identifying habitat features important to successful breeding, testing methods for creating appropriate breeding habitat, restoring degraded habitats, and restricting some human uses on breeding sites. For example, Ft. Lewis has restricted recreational activities on a breeding site and Olympia Airport has modified mowing dates and times to minimize impacts to Lark nests.

Because the subspecies migrates between Oregon and Washington and because the remaining breeding populations are found in the Puget lowlands, Columbia River/coastal Washington, and Willamette Valley, we recommend that local and regional recovery strategies consider rangewide population dynamics and threats so that recovery actions can be coordinated and focused on the activities that are most likely to result in increased Lark populations.