Songbird Numbers May Indicate Trouble in Northwest Forests

Numerous North American songbird populations are declining, and conservationists are not sure why – although 10 years of data indicate the reasons may be as varied as the birds themselves. Theories about why these bird populations are declining include reproductive issues and poor survival rates of adults, as well as possible changes in environmental conditions. In an effort to shed light on this murky problem, researchers analyzed 10 years of data from banding stations – where birds congregate in large numbers during migration – in the Pacific Northwest, which they detail in a study published Wednesday in the journal The Condor: Ornithological Applications.

“Before we can understand the impact of threats to bird populations, we first need to understand what’s happening where,” said co-author John Alexander, executive director of the Klamath Bird Observatory, which led the research. The team’s findings reveal that the issues plaguing songbird populations vary by group and location.

The 12 songbirds the researchers studied were chosen based on either regional conservation concern or habitat quality. The team used data collected between 2002 and 2013. Three of the species – the yellow-rumped warbler (Setophaga coronata), the dark-eyed junco (Junco hyemalis) and the purple finch (Haemorhous purpureus) – were declining, which the team attributes to habitat-quality issues. The researchers also found that breeding issues have contributed to the decline of three other songbird species. However, adult abundance reflected the previous year’s productivity for only one species, the yellow warbler, which suggests that local spawning is not the main force behind such population declines, according to the report.

“This study presents trends from regional-scale monitoring and just begins to scratch the surface of understanding population dynamics, variation in demographic rates, and drivers of population change across our landscape, which is vital information for developing effective conservation plans,” Alexander said.

Source
Court House News, ]september 27, 2017
https://www.courthousenews.com/songbird-numbers-may-indicate-trouble-no…