Landbird monitoring in the Chihuahuan Desert Network: 2010–2017 synthesis report

Colbaugh, Jessica; Gitzen, Robert; Valentine-Darby, Patricia; Levandoski, Greg; Powell, Melissa

doi:10.36967/2307228

The CHDN began monitoring landbirds in 2010 and now has monitoring data in all parks for the breeding seasons of 2010–2016 (except 2015), as well as 2017 for Big Bend NP. Our intention for monitoring landbirds extends beyond the birds themselves, and includes a broader vision of landbirds as indicators of the ecosystems they inhabit. This dual purpose influenced our sampling design, especially in light of funding and logistical limitations. We sampled primarily in two habitat classes in the CHDN: grassland (upland) and riparian. Depending on park size, we used two approaches to allocate survey point locations (Generalized Random-Tessellation Stratified sampling [GRTS] in all but one park, and a systematic grid in Fort Davis NHS). From our species richness and composition analysis, we found that across all parks the largest species richness estimate was in Amistad NRA riparian habitat in 2013, and the lowest species richness estimate was in Carlsbad Caverns NP riparian habitat in 2010. In total, we detected 104 breeding species that are well-surveyed by the methods used. Across parks and habitats, we obtained occupancy estimates for about 250 species-park-habitat combinations. In upland habitat we estimated occupancy for 50 species, and in riparian habitat we estimated occupancy for 58 species. Of these species, we obtained high precision (CV ≤10%) for a small subset (16 species in upland habitat and five species in riparian habitat). Similarly, across parks and habitats, we obtained density estimates for 81 species-park-habitat combinations. We estimated density of 30 species in upland habitat and 11 species in riparian habitat. We present occupancy and density estimates from our analyses in the form of “species accounts” for all breeding species that we considered adequately surveyed by the methods used (i.e., excluding colonial, nocturnal, and low-breeding-density birds) and for which sufficient data were available for the analyses. This resulted in 51 species accounts. In addition to occupancy and density results (by park-habitat), we included a conservation status table with 12 different scores/rankings (at global, continental, federal, regional, and state scales) for each species. We estimated occupancy and/or density for seven species of conservation concern: Bell’s Vireo (state-threatened in New Mexico), Black-chinned Sparrow (continental watch list species), Cactus Wren (regional concern), Cassin’s Sparrow (regional concern), Loggerhead Shrike (regional concern), Lucy’s Warbler (regional concern), and Scott’s Oriole (regional concern).

Landbird monitoring in the Chihuahuan Desert Network: 2010–2017 synthesis report

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