Landbird Population Trends in the Northern Colorado Plateau Parks, 2020

A rock wren. NPS photo.

Fifteen years of monitoring in the Northern Colorado Plateau Network's parks have found 11 significant trends in breeding-bird populations: nine declines and two increases.

Why monitor landbirds

Birds sit at several levels of the food web and help move energy through ecosystems. Because they respond to changes in habitat, they are good indicators of an ecosystem's health, and they are popular: unlike many Colorado Plateau animals, visitors see them often. Data from the network's relatively natural park habitats give a baseline to compare with more disturbed places.

Managers need to know which species are present in order to manage for them, and a decline or rise in a species or habitat can warn of wider change. The data also feed park planning, such as Natural Resource Condition Assessments and State of the Park reports, and show what unspoiled park landscapes are worth to birds.

Where and how

In a typical year the Northern Colorado Plateau Network (NCPN) monitors birds at Arches, Canyonlands, Capitol Reef and Zion national parks and at Colorado, Natural Bridges and Pipe Spring national monuments, as well as the five parks surveyed in 2020 (below). Trends are measured by habitat, not by park: each breeding season a partner organisation surveys 15 transects in each of three habitats, low-elevation riparian, pinyon-juniper and sage shrubland. Pipe Spring uses point counts and area searches in an adapted design.

The 2020 season

Because of COVID-19 closures and precautions, surveys were scaled back. Only sage shrubland transects were visited, at Black Canyon of the Gunnison and Bryce Canyon national parks, Dinosaur and Fossil Butte national monuments and Curecanti National Recreation Area, and no point counts were done at Pipe Spring. The 210 point-count surveys at those five parks found 73 species, none new to the programme or to any park. Since monitoring began in 2005 there have been 14,483 point-count surveys in the 11 parks, recording 173 species.

Trends

Of 121 population-density trends estimated across the three habitats, 11 are statistically significant (p < 0.05):

NCPN landbird population trends, 2005–2020. NPS.

Low-elevation riparian habitat had the most significant declines; the only two increases were one each in riparian and pinyon-juniper habitat. Improved methods of analysis changed some trends from earlier reports.

Sources

• National Park Service, Northern Colorado Plateau Network, "Landbird Population Trends in the Northern Colorado Plateau Network, 2020." https://www.nps.gov/articles/000/ncpn_landbirds20.htm
• Summarised from S. G. Roberts, E. L. Tymkiw, Z. S. Ladin and W. G. Shriver, Landbird monitoring in the Northern Colorado Plateau Network: 2020 field season (2020).