Study reveals key wintering locations for declining songbird

11/08/2019

Many of North America's migratory songbirds, which undertake awe-inspiring journeys twice a year, are declining at alarming rates. For conservation efforts to succeed, wildlife managers need to know where they go and what challenges they face during their annual migration to Latin America and back.

For a new study published by The Condor: Ornithological Applications, researchers assembled an unprecedented effort to track where Prothonotary Warblers that breed across six states in the eastern US go in winter, and found that nearly the entire species depends on a relatively small area in Colombia threatened by deforestation and sociopolitical changes.

Ohio State University's Christopher Tonra and his colleagues co-ordinated the deployment of 149 geolocators – tiny devices that use the timing of dawn and dusk to estimate birds' locations – on Prothonotary Warblers captured at sites across their breeding range. When the birds returned to their nesting sites the following year, the researchers were able to recover 34 devices that contained enough data for them to use. The geolocator data showed that regardless of where they bred, most of the warblers used the same two major Central American stopover sites during their migration and spent the winter in a relatively small area of northern Colombia. Additionally, many Prothonotary Warblers appeared to winter in inland areas, rather than in coastal mangrove habitat, which previous studies had suggested they relied on most heavily.

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METCALFE: The Warbler among rarest birds in Canada

ZACK METCALFE THE ENDANGERED PERSPECTIVE 

Published July 16, 2018 - 8:52am
Last Updated July 16, 2018 - 8:53am

The prothonotary warbler ranks among the rarest birds in Canada, but then, it probably always has. Showing a clear preference for the warmth of the United States, its only foray into Canada occurs in the Carolinian forests of southern Ontario, a region I visited just last month.

Point Pelee National Park is the southernmost tip of our country, an arrowhead of land reaching boldly into Lake Erie, resting farther south even than northern California. Two-thirds of this outstanding park are made up of wetlands, and where forests stand in swamp is where this fascinating warbler prefers to nest.

Their Canadian population was estimated at 28 individuals in 2015, forming fewer than 10 active nests between them each annum. In 2018, at the time of my visit, two of these nests resided in Point Pelee, reachable, more or less, by trail.

The forested wetlands in which they nest are a site to behold; perfectly still ponds of water formed by the omnipresent tumult of Lake Erie. In them stand hardy trees creating a suffocating canopy, complimented underneath by a blanket of lime green vegetation obscuring the water.

A series of regular, sharp tweets signalled the presence of this brave bird, defending the territory surrounding its nesting box, erected by Parks Canada staff in the water and greenery. I saw him dart from perch-to-perch, collecting food for his nest, apparently housing his better half.

The prothonotary warbler is listed as endangered in Canada, given its rarity and the draining of its wetland habitat, but across the entirety of North America, it’s doing well enough, numbering an estimated 1.6 million strong. Its national endangerment is a matter of borders, and the fact that our 28 individuals reside on the northern edge of the species’ range, but this, I’ve learned, did not make their conservation any less important.

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Geolocators used to link breeding and wintering populations of Prothonotary Warblers

September 22, 2015

Prothonotary Warblers are stunningly beautiful and highly migratory birds closely tied to their preferred breeding habitat: swamps and other forested wetlands in the eastern United States. Scientists have noted that Prothonotary Warbler populations have experienced precipitous declines in recent years, prompting new research investigating the little known migratory behavior of this remarkable bird. As part of this effort, researchers from the U.S. Forest Service Pacific Southwest Research Station, Klamath Bird Observatory, Louisiana Bird Observatory, and Audubon Louisiana attached several geolocators—ultra-lightweight devices that record the time of sunrise and sunset each day—using a back-pack harness on several Prothonotary Warblers to identify their migratory routes and core wintering areas. The information collected by each geolocator was used to estimate the daily longitude and latitude of the bird.

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