Tuesday
May082018

Birds of the Joint Base Lewis-McChord Prairies

Curious what the most common birds are on the Joint Base Lewis-McChord (JBLM) Prairies? Since 2015, the CNLM Avian Conservation Program has been collecting data on prairie birds and vegetation on JBLM, a military base that supports some of the most extensive prairie habitats in the region. Estimating abundance and determining relationships between bird species and vegetation can help us determine population size and make management decisions that create vegetation conditions to help these populations grow.

Following Euro-American settlement, prairie habitats in the Puget Lowlands have been substantially degraded due to human development and lack of fire. Historically, prairies also supported a unique avian community, but in response to these changes many prairie birds have experienced population declines, including the streaked horned lark (Eremophila alpestris strigata), a federally-threatened species, and the Oregon vesper sparrow (Pooecetes gramineus affinis), a species recently petitioned for federal listing.

A female Oregon Vesper sparrow (Pooecetes gramineus).

From 2015-2017, the savannah sparrow was the most prevalent species, detected over 4,000 times! The second most common species, the white-crowned sparrow, was heard 857 times, and chipping sparrow was heard 601 times. To compare that with our two declining species, the Oregon vesper sparrow was only heard 210 times and the streaked horned lark just 73 times in the three years!

A Lazuli bunting (Passerina amoena) caught by researchers.

Although prairies may look identical to the naked-eye, some early results show that there are big differences in bird abundance and composition among prairies. We suspect this variation is due current vegetation conditions, which are ultimately driven by a variety of factors including historic and current management.  Ongoing analysis will continue to investigate specific relationships between bird populations and vegetation on our prairies. Results will contribute to a better understanding of the population size of rare birds, such as the Oregon vesper sparrow, and help develop management strategies for these unique birds.

Scouting for birds on the JBLM prairies.