Arid Lands Field Station

UNM Biology Department MSC03 2020
1 University of New Mexico
Albuquerque, NM 87131-0001

In the News

New Paper Describes Migratory Bird Use of Southwestern U.S. Habitat

A new paper in the journal Condor, authored by USGS scientists Janet Ruth, Robb Diehl, and others, describes how the authors used radar data and satellite land-cover data to identify the various habitats with which birds are associated during migration stopovers. Their results suggest that it is too simplistic to (1) consider the arid West as a largely inhospitable landscape in which there are only relatively small oases of habitat that provide the resources needed by all migrants; (2) think of western riparian and upland forests as supporting the majority of migrants in all cases, and (3) consider a particular habitat unimportant for stopover solely on the basis of low densities of migrants. Read the entire paper here.


Bird migration and stopover habitat use in the Southwest

To ensure full life-cycle bird conservation, we need to understand migrant behavior en route and how birds use habitat during stopover. Birds traversing the Southwest are known to use riparian stopover habitats; we know less about how migrants use other habitats and how density varies across the region seasonally and annually. Using weather radar data, we found that in fall there was greater passage of migrants through the central part of the borderlands; in spring there was some suggestion of greater passage in the eastern borderlands. Density patterns are consistent with the existence of more than one migration system through western North America and seasonally different migration routes for at least some species. Presence of bats in the data complicates some interpretations. We combined radar and land cover data to determine migrant stopover habitat use. There were significant differences in bird densities among habitat types at all radar sites in at least one of three seasons studied. Upland forest habitat in parts of Arizona and New Mexico supported higher migrant densities than other habitat types, especially in fall. Developed habitat in areas with little upland forest habitat also supported high migrant densities. Scrub/shrub and grassland habitats supported low to intermediate migrant densities, but because these habitat types dominate the region, they may support larger numbers of migrants than previously thought. This may be especially true for non-forest species. Further research is needed to address issues of target identity and to confirm the importance of these habitat types to migratory birds.