Landbird monitoring in the Northern Colorado Plateau Network: 2018 field season

Roberts, Samuel; Tymkiw, Elizabeth; Ladin, Zachary; Shriver, W.

In 2018, the University of Delaware, in cooperation with the National Park Service (NPS), completed the thirteenth year of a habitat-based landbird monitoring program in park units of the Northern Colorado Plateau Network (NCPN). This program is designed to provide rigorous data on population trends for most diurnal, regularly occurring breeding landbird species throughout the network. This population information is useful for land managers and supports the National Park Service’s goal of conserving park resources through long-term monitoring of biological indicators. In 2018, university biologists surveyed 45 locations within 11 NPS units. Fifteen transects were located in each of the three habitats of interest: low-elevation riparian, pinyon-juniper, and sage shrubland. Each location was surveyed once. In addition to the habitat-based surveys, four point counts and an area search were conducted at Pipe Spring National Monument, using a modified monitoring design. Over 13 years of data collection, 13,618 point-count surveys have been conducted in 11 NCPN units, detecting 167 unique species. During the 2018 field season, 644 point-count surveys were conducted, detecting 103 unique species. One new species was detected for this monitoring program: a summer tanager, during a low-elevation riparian transect survey in Zion National Park. In total, 135 population-density trends were estimated across the three habitats. Twenty-two of these estimated trends were significant (p-value <0.05), including 15 negative trends and 7 positive trends. There were sufficient sample sizes to estimate the densities of 64 species in at least one of the three habitats surveyed. Using a modified monitoring design, landbird monitoring surveys were conducted in Pipe Spring National Monument for the ninth year since 2009. A total of 131 individuals of 40 species were recorded. Three common yellowthroats, a Lincoln’s sparrow, and a Cassin’s finch were detected for the first time by this monitoring program, and a migrant northern waterthrush was detected for the first time within park boundaries. Sample sizes were too low for density trends to be estimated for Pipe Spring National Monument. Due to differences in distance sampling methodology, all density estimates in this report should replace those found in reports from previous years.

Landbird monitoring in the Northern Colorado Plateau Network: 2018 field season

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