Authors: Paul A. Smith, Adam C. Smith, Brad Andres, Charles M. Francis, Brian Harrington, Christian Friis, R. I. Guy Morrison, Julie Paquet, Brad Winn, and Stephen Brown
Year: 2023
Publication: Ornithological Applications
Publication Link: https://academic.oup.com/condor/article/125/2/duad003/7031074
Keywords: citizen science, migration, North America, population decline, shorebirds, trend analysis, wildlife surveys
Abstract: Shorebirds are declining to a greater extent than many other avian taxa around the world. In North America, shorebirds, along with aerial insectivores
and grassland birds, have some of the highest proportions of declining species of any group. Here, we apply a new hierarchical Bayesian model
to analyze shorebird migration monitoring data from across North America, from 1980 to 2019, and present the most recent available estimates of
trends for 28 species. Point estimates for survey-wide trends in abundance were negative for 26 of 28 species (93%). Despite challenges with low
precision associated with migration count data, trends for 19 species had 95% credible intervals that were entirely negative. More than half of the
species were estimated to have lost >50% of their abundance. Furthermore, estimated rates of decline have accelerated during the last three generations
for most species. Point estimates of trend were more negative for 18 species (64%) during the most recent three-generation period in comparison
to the previous three-generation period. Many species now exceed international criteria for threatened species listing. The analytic approach
used here allows us to model regional variation in trends, although survey coverage and strength of inference were greatest in the eastern portions
of North America (east of 100°W). We found the greatest declines at staging sites along the Atlantic Coast from North Carolina to Nova Scotia, and
lesser declines along the Gulf Coast and in the midcontinental United States. The declines in shorebird populations reported here are worrisome and
signal the urgent need for conservation action. In addition, it would be beneficial to validate these results through the collection and analysis of complementary
data, and to initiate demographic studies throughout the annual cycle to determine where and when declines are most likely to originate.
This improved information will allow for the development of more targeted efforts to reverse declines through conservation action.