Declining Golden-winged Warblers Passing Through Iowa

For Iowa birding enthusiasts, the spring warbler migration is a highlight event.  Not all migrations are created equal, of course.  The speed, timing, and abundance of the annual flights are largely dependent on developing spring weather patterns.  Not all warbler sightings carry the same weight.  While enjoying and identifying the more common species, experienced birders are always on the lookout for a more rarely seen visitor.

The tiny golden-winged warbler is one of those species.  A small grayish warbler with short tail and bright patches of gold on the wings and crown, the golden-wing’s ongoing decline in numbers has been so dramatic that it currently thought to have one of the smallest populations of any bird not currently listed on the endangered species list, according to Ithaca, New York’s Cornell Lab of Ornithology.  It’s no wonder that I was understandably surprised when I received two nearly simultaneous reports of the species in Cerro Gordo County on Saturday, May 4^th.  The first call — accompanied by a documenting phone photo — came after Ron and Carol Burkholder spotted a male golden-winged in the woods at their home south of Clear Lake.  The second observation came minutes later when Thornton’s Paul Willis spotted a second male at the McIntosh Woods State Park.

According to scientists with The Nature Conservancy, there have been several reasons for the golden-wings’ dramatic decline.  The tiny bird is a long-distance, intercontinental migrator which, in itself, comes with a long list of inherent dangers.  Other negative factors include the golden-wings’ tendency to hybridize with the blue-winged warbler and massive land use changes on the species nesting and wintering grounds.  In the Appalachian Mountains, an alarming 98 percent of the species’ previously existing populations have now vanished.  Currently, 95 percent of the species’ entire world population nests in Wisconsin, Minnesota, and Manitoba.  Minnesota’s swamp edge nesting habitats currently provide summer homes for about half of the golden-wing’s global population – a statistic that is beyond alarming.

Following the summer nesting season, golden-wings embark on a long and dangerous migratory journey that leads down the Mississippi Flyway, south through Texas, Mexico, and Central America.  The annual flight eventually terminates in the forested wintering grounds of South America. 

The golden-winged warbler is currently listed on the Conservation Red Watch List and is being considered for endangered species status by the U.S. Fish & Wildlife Service.  In the meantime, the Cornell Lab and The Nature Conservancy are joining forces with nearly 40 other conservation groups and universities in efforts to protect and enhance the warbler’s mid-continent breeding habitats.  In Iowa, the best opportunities for viewing a golden-winged warbler are in May during spring migration and again in September and early October.