The Fascinating Kirtland’s Warbler

One of the rarest members of the Parulidae family, the endangered Kirtland’s warbler captures the attention of avid birders for a number of reasons. The breeding range of this small neotropical migratory bird is limited to an area in the north of Michigan’s Lower Peninsula, in the province of Ontario and in Wisconsin.

The Kirtland’s warbler has a blue-grey face and back, with a yellow throat, chest and belly. It has white crescents above and below its eyes, black stripes down its sides and white wingbars. It has a distinctive manner of frequently pumping its tail up and down. It eats insects and berries, and has been known to eat fruit, especially in winter. In summer the Kirtland’s warbler is readily seen perched on young jack pine branches and singing loudly, but in its Bahaman Islands wintering grounds, it proves to be incredibly elusive.

To enable it to breed successfully, the Kirtland’s Warbler requires areas with small jack pines and open spaces. They nest in groups either on the ground among grass or on other plants under the limbs of young jack pines. As the trees mature and the upper branches prevent sunlight from reaching lower branches, these lower branches die off and the warblers abandon the area. Jack pine cones are opened by fire facilitating the spread of the seeds and subsequent growth of new trees. However, due to efforts by authorities to suppress fires, which can quickly get out of control, the nesting sites for the Kirtland’s Warbler decreased drastically. This is seen as a major contributing factor to the decline in numbers resulting in the warbler being declared as an endangered species. Another contributing factor in the decline in Kirtland’s Warbler numbers is that brood parasitic Brown-headed cowbirds lay their eggs in the warblers’ nests, leaving the warblers to hatch and raise their young. This is more often than not to the detriment of the warbler nestlings, which are often killed by the cowbird intruder.

In an effort to increase the number of these fascinating birds, the Kirtland’s Warbler Wildlife Management Area, which is managed by the Seney National Wildlife Refuge, includes 119 sites across eight counties. Management of the sites includes ensuring that the Kirtland’s warbler has suitable breeding grounds. Houses are scattered throughout the state forests surrounding the areas designated as Kirtland’s warbler breeding sites, and jack pines have an explosive wildfire nature, therefore, it is too hazardous to burn areas to create ideal nesting conditions. Instead, timber cutting along with direct seeding and planting has been successfully implemented. Efforts are also being made to keep the Brown-headed cowbird numbers to a minimum in managed areas.

Other birds that may be found in the Kirtland’s warbler nesting grounds include spruce grouse, Nashville warbler, eastern towhee, black-backed woodpecker and brown thrasher. Bird-watchers who would like to observe the Kirtland’s warbler can obtain information from the Seney National Wildlife Refuge with regard to the locations of the managed sites.