Photo by Scott Wright. Image copyrighted and used with photographers permission.

The Kirtland's warbler was not identified until 1851. It was named after Dr. Jared P. Kirtland, a distinguished naturalist and physician from Ohio. It was Kirtland's son-in-law who found the small, blue-gray and yellow bird, which was likely on its way back to Michigan after having spent the winter in the Bahamas, their exclusive migration destination.

Life History

Kirtland's warbler belongs to the family, Emberizidae, which also includes species such as other warblers, cardinals, many sparrows, several blackbirds, scarlet tanagers, cowbirds, and several orioles. Kirtland's warblers are usually about six inches in length, about the size of a house sparrow. During the breeding season, the males have bluish-gray backs with black streaks and yellow breasts, with some black spots on the sides and occasionally on the breast. Their cheeks are black, while their eyes have a very conspicuous white eye-ring. Females are similar, but with duller colors and lighter cheeks.

The diet of the warbler includes many different insect species at various developmental stages, including caterpillars, butterflies, moths, flies, grasshoppers, as well as ripe blueberries, when in season. Each fall, they migrate to the Bahamas and nearby islands, where their food sources are available throughout the year.

Kirtland's warblers have very specific nest site requirements. They will only nest on the ground in large areas of young jack pine forest that are between five and 20 feet tall, preferably with extremely high densities of trees. The low branches on the young trees protect the nest from predators. When the trees reach about 15 years of age the branches at the bottom begin to die, leaving the nests exposed. Kirtland's then finds these trees undesirable for nesting. They are found most often in forest stands of 200 or more acres (studies have shown they actually seem to prefer stands of 1,000 or more), and rarely in forest stands of less than 80 acres. This type of habitat is very limited and currently the only known nesting sites of the species are within a few small areas in the northern Lower Peninsula of Michigan and a small area of the Upper Peninsula. This area has a particular type of sandy soil in which jack pine trees will grow. The area is also fire-prone, which is necessary for the jack pine trees to release their seeds, and has historically provided a perpetual supply of young forest stands for the warblers. Jack Pine Plantations have also shown to be favored habitat for the Warblers which may eliminate the need to purposely set fires to clear areas of old growth and lessen the danger of damaging adjacent properties.

Male Kirtland's warblers arrive back in Michigan from the Bahamas between May 3 and May 20, a few days ahead of the females. The males establish and defend territories and then court the females when they arrive. As the female builds a nest of leaves and grass, the male begins to bring her food. This duty continues through egg laying and the incubation process, with which the males rarely help. Five eggs are laid in late May, followed by an incubation of 13-16 days. Both parents feed the chicks, which grow quickly and have left the nest within nine days, staying in the undergrowth and lowest branches of the trees. Within five weeks, the parents have ceased feeding their young.

History in Michigan

The first Kirtland's warbler to be described was found in 1851 near Cleveland, OH. Their wintering grounds were found in 1879, but their breeding grounds here in Michigan were not discovered until 1903. It was discovered in northern lower Michigan in Oscoda County about one half mile east of the Crawford County line and a mile north of the AuSable River. Every single nest found by 1992 was within 60 miles of that original nest. Kirtland's warblers are believed to have originally nested in 13 counties in Michigan, and, based on non-breeding males sighted during annual surveys, they may also have nested in the Upper Peninsula, Wisconsin and Canada.

Historical reports from collectors in the Bahamas from 1880 to 1900, suggest that there were far greater numbers of warblers at that time. The first survey of singing males in 1951 found 432 males, followed by 502 in 1961. However, there was a 60 percent decrease in numbers between 1961 and 1971, when only 201 were counted. The birds are counted by listening for their songs. In June, males establish territories and use their songs to fend off rival males and attract mates. The songs can be heard over one-quarter mile away, providing a method to count the birds with minimum amount of disturbance. The females do not sing. The total minimum breeding population is twice the number of singing males.

The incredible decrease in Kirtland's warblers between 1961 and 1971 is probably mostly due to a decrease in the available suitable nesting habitat. This loss can probably be attributed chiefly to fire suppression management, which resulted in a drastically decreased production of young forest. A secondary cause of the decrease in numbers of warblers was cowbird parasitism. Cowbirds lay their eggs in the nests of other birds and since the cowbird chicks hatch sooner and are larger and more aggressive than the chicks of the host nest, they receive more food than the warbler chicks. If one cowbird egg is laid, one to three of the warbler chicks may survive. However, if two cowbird eggs are laid, none of the warbler chicks will survive -- they just can't compete.

In 1972, a policy of cowbird control was initiated by the U.S. Fish and Wildlife Service with the U.S. Forest Service, Michigan Department of Natural Resources, and Michigan Audubon Society. The rate of parasitism was reduced from 69 percent in 1966-71 to less than 3 percent by 1982. By 1983, the number of warbler fledglings per pair of Kirtland's warblers had increased from 1.0 to 3.1.

The Kirtland's Warbler Recovery Team was established in 1975 by the U.S. Fish and Wildlife Service to monitor the recovery of the warblers and to insure that the objectives of the Recovery Plan are met. The Recovery Plan calls for regeneration of jack pine habitat through harvest and/or burning on state (60%) and federal (40%) lands comprising 51,700 hectares. The goal is to have 10,340 hectares of suitable habitat available each year, and a minimum of 1,000 breeding males throughout the warbler's former range.

The population of Kirtland's warblers was reasonably steady through the 1980s at around 215, with some fluctuations that were associated with rainfall in the Bahamas (greater rainfall = more insects). The 1990 singing male survey reported an increase: 265 males were counted. This was followed by a rapid increase in the early 1990s. The 1995 survey found 766 singing males and last year's total (1999) was 885 in the Lower Peninsula and 18 in the Upper Peninsula for a total of 903 singing males! This is wonderful news! For the latest (2000) DNR report click on this link. http://geocities.datacellar.net/Heartland/Cottage/8090/2000DNRreport.html

The people of Michigan have embraced the Kirtland's warbler as a symbol of the need to protect and provide habitat for the wildlife in our state. The Sixth Annual Kirtland's Warbler Festival was held this past spring (1999) at Kirtland Community College, 10775 N. St. Helen Road,
Roscommon, MI 48653; participants included people like Photographer Carl Sams II, Artist Michael Glenn Monroe, Presenter Mark Herrick (?Buck Wilder), Birds of Prey presenter Joe Rogers, and, Kim Williams, from the Michigan Organization for Bat Conservation, to name just a few. Free guided tours to Kirtland's warbler nesting areas and self-guided auto tours of jack pine wildlife viewing areas are now available. The date for the next Kirtland?s Warbler Festival is May 20, 2000.
For information on 2000 Kirtland's Warbler Tours check out their web page at http://www.fs.fed.us/r9/hmnf/pages/warbtours.htm or e-mail figleys@kirtland.cc.mi.us

Also check out these other Kirtland's Warbler links. Kirtland's Warbler Festival, http://www.kirtland.cc.mi.us/~warbler