Kirtland’s Warbler Population Stabilizes

September 27, 2011 by  
Filed under News

Kirtland’s Warblers have very specific habitat requirements and are found only in the jack pine forests of Ontario, Michigan and Wisconsin. Due primarily to habitat changes, the numbers of these elusive little birds were declining drastically, but thanks to ongoing conservation efforts, recent research by the Michigan Department of Natural Resources has revealed that the population not only appears to have stabilized, it may even have grown. More than twenty years ago the Kirtland’s Warbler population in northern Michigan had declined to a count of 167 pairs.

The Kirtland’s Warbler count takes place in the second and third weeks of June each year, as this is the time when they defend their nesting territories and become quite vocal about it. The birds are very elusive and would be difficult to detect if it were not for their distinctive song. Only the males sing, and total population is based on the assumption that each male has a mate. The count carried out in June 2010 recorded 1,747 males, with this year’s count indicating that 1,805 males are resident across their habitat range. Two pairs were located in Ontario and another 21 in northern Wisconsin.

Kirtland’s Warblers select nesting sites in jack pine forests where the trees are between four and twenty years old. In the past, nature would create these new forests as wildfires swept through the area burning down the older trees and making way for seedlings to sprout and grow. This natural cycle has been interrupted by humans who have implemented fire suppression programs in the interests of safety. Even so-called ‘controlled’ fires can get out of hand and are considered too risky an option for reestablishing the natural order of things. So, in order to recreate the effects of wildfire and allow the growth of new jack pine trees and other rare plants in the ecosystem, the Michigan Department of Natural Resources, along with the US Fish and Wildlife Service and the US Forest Service carry out a continuous cycle of cutting, burning, seeding and replanting, over an area of around 3,000 acres.

The program has proven to be successful in a number of ways. The Kirtland’s Warbler population has increased, and snowshoe hares, deer and turkeys are among the creatures that are thriving in the area. Moreover, the program is providing valuable timber without damaging the environment. Although the Kirtland’s Warbler population has grown, it remains on the endangered species list where it has been since 1973. It appears likely that the population has reached its peak determined by the habitat available to it, but with ongoing conservation measures, the Kirtland’s Warbler will still be around in the years to come.

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