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US Fish & Wildlife Service FieldNotes

Geolocators will shed new light on geographic distribution of Kirtland's warblers during the non-breeding season

Region 3, October 10, 2012
A small geolocator is worn like a backpack on this Kirtland's warbler.  A light sensor protrudes on a stalk above the feathers on the back of this male.
A small geolocator is worn like a backpack on this Kirtland's warbler. A light sensor protrudes on a stalk above the feathers on the back of this male. - Photo Credit: n/a

As the month of October began, the last few Kirtland’s warblers that remained on the breeding grounds in northern Michigan finally departed. They have embarked on a journey spanning more than 1,600 miles, shared by approximately 10,000 others of their kind. Many will likely pause enroute somewhere between Michigan and the Bahamas to rest and refuel before finally arriving at their winter home. The vast majority of these individuals will go undetected as they fly south, eluding the eyes of ever-watchful birders as they have done since the species was first discovered in 1851. A small sample of this population, however, promises to remove some of the obscurity associated with this species during the non-breeding season and literally shed light on where these birds spend the bulk of their time, outside of Michigan.

 

In the spring of 2012, Dan Elbert of the East Lansing Field Office began a project in collaboration with Dr. Pete Marra of the Smithsonian Institute to track the movement of Kirtland’s warblers from their breeding grounds to their winter grounds. Several Kirtland’s warblers were equipped with light-level geolocators during the 2012 breeding season. These devices are incredibly small, weighing just 0.65 g, and will record time and light intensity levels while the individual wears the device. Upon re-capture of these birds next spring, data archived on the device will be downloaded and analyzed to determine where those individuals have been (accuracy is approximately ± 200km). This information will help clarify the geographic distribution of the species during migration and winter seasons. It will also facilitate future studies that examine the biology and ecology of the Kirtland’s warbler during these important periods of its annual life cycle. Most importantly, this new information will increase our ability to identify and ensure that threats to the survival of this endangered species are adequately addressed across the entirety of its range.

Contact Info: Daniel Elbert, 517-351-7261, daniel_elbert@fws.gov