Not only is Kirtland’s Warbler our rarest warbler, it is also one of the most highly endangered species in North America.  Its’ habitat requirements are so specialized that it is restricted to a very limited breeding area, primarily in northern lower Michigan, especially along the Au Sable River drainage.  Extensive tracts of young Jackpines growing in the lose, sandy soil comprise the necessary conditions which also promote a dense understory of certain plant associations.

These areas are first occupied after about five or six years following a fire or clearcut when the trees are four or five feet in height, but are abandoned some years later as they attain heights of fifteen to eighteen feet.  At this age the lower branches die back and changes to the understory render them unsuitable  to the birds.

In earlier times new habitat was created solely by wildfires, which removed the old growth and provided the necessary heat to release the seeds from the pinecones, the only way regeneration could happen.  Today, prescribed burns in some areas, and clearcutting in others…followed by replanting of seedling pines, in some 150,000 acres of U. S. Forest Service and Michigan DNR lands, assure the warblers of future habitat.  These managed areas by governmental agencies not only benefit the Kirtland’s Warbler, but all other species associated with the Jackpine Ecosystem.  From a low of less than two hundred pairs in the l970’s before extensive management was begun, Kirtland’s Warbler populations now approach two thousand pairs in 2004.

The birds return to their breeding areas in early May, having spent the winter on certain islands of the Bahamas.  The loud, distinctive calls of the males can be heard for up to a quarter mile, and although more persistent in the earlier hours of the day, can be heard more or less throughout the daylight hours.

Kirtland’s Warblers nest on the ground, often near the base of a young pine.  The female tends all of the incubation, which lasts ten to twelve days.  During this period the male brings her food, sometimes directly to the nest, sometimes she leaves to accept it nearby and takes a five or ten minute break.  After the four or five eggs hatch, both parents bring food to the young in the nest.  They fledge at about ten days, some days before they can fly, but are constantly tended by their parents for the next couple of weeks until they learn to fend for themselves.

By late August all is quiet in the Jackpines as the birds complete their moults in preparation for their dangerous journey south to the Bahamas.  Many will not survive the trip, or the winter.  But those that do and make it back to Michigan the following May will find lots of new habitat awaiting them, thanks to the U.S Fish & Wildlife Service, the U. S. Forest Service, the Michigan DNR , the Nature Conservancy, and many dedicated volunteers.