Impacts of habitat fragmentation by agriculture on breeding songbirds in the Okanagan sagebrush shrubsteppe

The sagebrush shrubsteppe of western North America has been extensively fragmented by agriculture. I examined the impact of habitat fragmentation on songbirds by comparing community assemblage and nest success in sagebrush habitat near agriculture to habitat away from orchards or vineyards in the Okanagan region. The songbird community in edge habitat differed from the community in interior habitat primarily due to an abundance of generalist species in edge habitat. Local vegetation characteristics, landscape composition and the predator community all contributed to observed variation in the songbird community. Abundance of sagebrush specialist songbirds in edge and interior habitat varied with species, but overall, sagebrush songbirds initiated fewer per capita nesting attempts in edge habitat. Daily nest survival of sagebrush songbirds was lower in orchard edge habitat than in vineyard edge habitat or interior habitat. These results provide additional evidence that sagebrush fragmentation is contributing to observed population declines of sagebrush songbirds.