Kirtland’s Warbler (credit: Ron Austing).
“We are sea creatures living on land, wishing we could fly.”
—Carl Sandburg
The jack pine plains of north-central Michigan host a comeback story of surprising proportions. The diminutive Kirtland’s warbler is the rarest of the wood warbler family, and in many ways is the poster child for the migratory good life. The warblers fly to the Bahamas for the winter, and then breed by summer up in Michigan. But due to very specific habitat requirements, these little migrants with big voices are highly endangered.
Ornithologists didn’t describe this beautiful species until 1851 when a spring migrant was collected near Cleveland, Ohio. Eventually sent to the Smithsonian Institution, the species was named in honor of Jared Kirtland, a physician, naturalist, and author of the first lists of vertebrates in Ohio.
Due to their restricted home range and unique habitat requirements, Kirtland’s warblers have likely always been rare. They spend about eight months on their wintering grounds, arriving back in Michigan in May each year. The males come first to establish and defend their territories so they’re ready to court the females upon their arrival. Females build their nests among the grasses below jack pine trees while the males feed them larvae and bugs. Although the dads don’t build or brood, they are pretty fair providers, and at least they stick around to help feed the young. And these birds grow up fast. Young Kirtland’s warblers leave the nest by nine days of age, but stick around to be fed for another three to four weeks, perching on low branches or hiding in the grasses.
The challenge for the warblers is that they require a highly specific habitat in order to survive. During their breeding season, they can live only in a specific area dominated by a tree called the jack pine, which in turn grows only in a certain type of soil called Grayling sand. (Until the last five years, the only place the Kirtland’s warbler could find this unique habitat was in the northern Lower Peninsula of Michigan.) When the jack pines reach the age of about five years, the warblers move in and nest in the grasses and ground cover that grows beneath the branches of the trees. Once the jack pines reach twelve to fifteen years old, the lower branches no longer shade the area below in the same way; the ground cover changes, and the birds move on.
Originally, the jack pine forests replenished themselves through a natural cycle of fire. Jack pines are specially adapted to not only survive forest fires, but require them. Fires are necessary for the trees to open their cones. Kind of like a popcorn. In the mid-1960s, the US Forest Service (USFS) began experimentally managing the pines by replanting young trees in rows with grassy areas in between, which worked well as warbler habitat. Today the USFS manages nearly two hundred thousand acres of jack pine habitat on a rotating basis, trying to keep the maximum number of pines between the ages of five and fifteen years. After that they either burn an area and let it recover naturally, or clear-cut a section and replant. Without the intensive management of jack pines, the warblers would likely go extinct.
Ron Austing, a USFS contract photographer and longtime bird photographer, is one of the few wildlife agents allowed into the protected range of the warblers to document their behavior. He has been studying and photographing the Kirtland’s for many years—nearly as long as there has been a recovery program in place. He told me that this species “is staging a comeback” because of all the support it is being given by many government agencies and conservation groups, including the USFS, US Fish and Wildlife Service, Michigan Department of Natural Resources, The Nature Conservancy, and Michigan Audubon. In recent years, biologists have found a small number of Kirtland’s warblers nesting beyond their original range—into areas of Michigan’s Upper Peninsula and even northern Wisconsin and southern Ontario.
Though the Kirtland’s warbler is now adequately protected and jack pines well maintained, the birds still face challenges—this time not from the foibles of man, but from the competition of other birds. The biggest problem is nest predation by the brown-headed cowbird. Cowbirds do not build nests of their own. They lay their eggs in the nests of other birds, generally smaller birds and particularly warblers. These highly efficient parasitic brooders drastically reduce the number of warblers that survive. Historically, cowbirds lived on the plains, following the movements of the great bison herds—hence their name. And as Michigan was opened up by logging and farming, the cowbirds moved in. Completely naive to the threat, Kirtland’s warblers fell victim to their parasitic strategy.
“I can remember the first time I went up to photograph Kirtland’s warblers in the 1960s and we found three nests on the first day, but all three contained baby cowbirds,” Ron told me. The problem is that the cowbird hatchlings grow about twice as fast as the smaller warblers, eventually kicking the baby warblers out of the nest and killing them.
Today wildlife managers in the Kirtland’s recovery area remove five to six thousand cowbirds per year. Using live traps positioned in various locations within the warbler’s prime breeding areas, managers remove the cowbirds and dispose of them humanely. So far, it seems to be helping, said Ron. “In all the nests we have seen over the last five years, we have not seen a single cowbird parasitizing a warbler nest. But do not ever forget that in order for the Kirtland’s warblers to succeed, they are going to have to be managed, both for habitat and with cowbird removal.”
And recovery of the species is indeed happening. When biologists first started doing surveys, the population numbered fewer than two hundred singing males. (They count the singing males because they are easy to identify in the spring nesting season, and a much more reliable census metric than trying to distinguish them by sight or by crawling through the grass searching for actual nest sties.) In 2007, the count in northern Michigan was nearly seventeen hundred. Of course, for every singing male there is a female mate building a nest over an area tremendously wider than forty years ago, when the conservation program was begun.
One great part of the comeback of this little half-ounce bird is that it is a superstar in the region where it nests in northern Michigan. Each May, the Kirtland Community College, in cooperation with the Michigan Department of Natural Resources and the US Fish and Wildlife Service, hosts the Kirtland Wildlife Festival in honor of the return of their native symbol. Over time, this celebration has become a national draw, with speakers, programs, and performers from across North America and the Caribbean.
Another terrific result of the growing interest in protecting the Kirtland’s warbler is research and conservation on its wintering grounds on the island of Eleuthera in the Bahamas. There, Bahamian college students are finding out just exactly where the warblers go and what they eat in the winter—bugs and fruit that are very different from their midwestern fare. In turn, professors at Kirtland Community College in Michigan, together with support from The Nature Conservancy and the US Fish and Wildlife Service, are working with the students and helping them get admitted into graduate programs in biology.
What this little bird’s recovery can teach us it that it really does take a village to save a species. From federal protection to adaptive strategies for habitat and parasite protection, hundreds of experts have played a part in this comeback story. But just as importantly, the plan includes the community in the equation as well. By managing enough forest, there is room and time for logging, yes, including clear-cutting, controlled burning, and replanting. All this work provides good jobs in a rural area. And that means the community has embraced the successful protection and restoration of this delicate songbird.
