Landbird monitoring in the Northern Colorado Plateau Network: 2012 field season

McLaren, Matthew; Blakesley, J.

In 2012, the Rocky Mountain Bird Observatory (RMBO), in cooperation with the National Park Service, completed its eighth year of a habitat-based landbird monitoring program in the Northern Colorado Plateau Inventory and Monitoring Network. This program is designed to provide rigorous population trend data for most diurnal, regularly occurring breeding landbird species throughout parks of the Northern Colorado Plateau Network (NCPN). This population information is useful for land managers and supports the National Park Service’s goal of long term monitoring of biological indicators for network parks. The program is also consistent with goals emphasized by the U.S. North American Bird Conservation Initiative Monitoring Subcommittee (2007). In 2012, RMBO biologists surveyed 45 transects twice within 11 NCPN units. Fifteen transects were located in each of three habitats of interest: low-elevation riparian, pinyon-juniper, and sage shrubland. To increase sample size, we surveyed all transects twice during the breeding season. In addition to the habitat-based surveys, we conducted four point counts and four area searches twice at Pipe Spring National Monument using a modified monitoring design. In 2012, we completed 100% of the assigned habitat-based surveys between May 5 and July 4. We recorded a total of 9,411 birds of 124 species. We detected 3,021 birds of 82 species in low-elevation riparian, 2,862 birds of 76 species in pinyon-juniper, and 3,528 birds of 94 species in sage shrubland habitats. We recorded two new species (American wigeon and northern pintail), both at Fossil Butte National Monument. At Pipe Spring National Monument, we detected a total of 328 birds of 31 species. We detected 86 birds of 18 species during point counts and 242 birds and 13 additional species during nocturnal and diurnal area searches. We estimated densities of 58 species in at least one habitat. In 2012, we were able to estimate densities of four species for which we were not able to provide estimates in previous years, due to the increased number of detections over all years. The data yielded robust density estimates (coefficient of variation <50%) for 37 species in at least one habitat in 2012. We recorded 42 bird species that are of conservation or management concern throughout the NCPN and estimated densities for 24 of these species. We estimated population trends for the 24 species of conservation or management concern for which we estimated densities. Separate analyses were performed for each habitat. Significant trends were evident for 10 species. Seven species exhibited declines in population density, one species exhibited an increase, and two species exhibited an increase in population density in early years, followed by a decrease in later years. As additional years of data accumulate, trend analysis will become less sensitive to short-term fluctuations in population density and long-term trends underlying annual fluctuations will be revealed.

Landbird monitoring in the Northern Colorado Plateau Network: 2012 field season

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