Estimating Streaked Horned Lark Over-winter Survival and Site Fidelity

Streaked horned lark populations may be regulated by reproductive rates, first year survivorship and/or adult survivorship. For this species, we currently have good information on reproductive success by location in Washington. However, we know little about year-to-year survivorship for first year or adult birds. First year survivorship is critical to population recruitment and often regulates bird populations. Consequently, our goal is to estimate first year and adult survivorship using mark – resight methods (similar to mark – recapture but does not require recapturing birds). Our second goal is to determine whether or not streaked horned larks exhibit site fidelity and, if so, to what degree. Again we will use mark – resight information to accomplish goal. Information on site fidelity is critical information for developing effective conservation strategies (especially when attempting to establish new populations). This study found that adult site fidelity is extremely high suggesting that it may be difficult to move adult birds to alternative sites. First year site fidelity is weaker suggesting that a small portion of young birds may be willing to move to alternative sites. For young of the year, it appears that most mortality occurs on the nesting grounds in the first few weeks after leaving the nest. High mortality during this period is likely the result of predation.