A Record Count of Kirtland’s Warbler in the Upper Peninsula of Michigan
Reported by the US Forest Service
This year was the 23rd consecutive year of searching young jack pine in the Upper Peninsula for the federally endangered Kirtland’s Warbler. In June, census participants counted 53 singing males, in 7 counties, across federal, state, county and industrial land-ownerships of the Upper Peninsula. The 2016 Upper Peninsula census showed a 43% population increase from 2015, and was the largest number of Kirtland’s Warblers ever recorded here.
“This increase is largely the result of efforts to manage the jack pine ecosystem in a way that encourages Kirtland’s Warbler breeding, specifically by creating large stands of dense young jack pine using commercial timber harvest, reforestation and prescribed burning,” stated Steve Sjogren, Hiawatha National Forest Ecologist.
Number of singing males counted in each Upper Peninsula County in June 2016
|County||Number of Singing Males|
While this peripheral breeding population represents just a small fraction of the total population it is extremely important to the overall recovery of this endangered species.
“With such a small total population it is essential that the species expands and colonizes new territory, as an insurance policy, in case some catastrophic event such as a large wildfire or a new insect or disease impacts the jack pine habitat in the relatively small core of the range,” Sjogren said.
The annual Upper Peninsula Kirtland’s Warbler census is conducted by several agencies including the Hiawatha and Ottawa National Forests, the US Fish and Wildlife Service Migratory Birds and Ecological Services offices, Seney National Wildlife Refuge, the Michigan Department of Natural Resources and volunteers from the birding community. These groups collaborate to conduct the annual census of Kirtland’s Warblers each June. The census enables managers to evaluate the size of the population, determine where the birds are nesting to protect them during the nesting season, and to evaluate the effectiveness of management activities.
The census is a count of singing males. Each singing male Kirtland’s Warbler is assumed to represent a breeding pair. Each morning, agency biologists and volunteers traverse young jack pines listening for their distinctive song. Census participants rise very early, starting at 5 am each morning and generally completing counts by 11 am. The locations of the males are plotted on maps. All of the singing males are counted to come up with a total for the stand, County and entire Upper Peninsula.
The Kirtland’s Warbler is a migratory songbird that has been listed as an endangered species since 1973. Known as a habitat specialist, they nest only in large areas of dense young jack pine. The majority of the spring and summer population, can be found at the center of the bird’s breeding range, in the northeastern Lower Peninsula of Michigan. In 2015 there were 2,365 singing males tallied. This number, although still small for a species global breeding population, is an incredible increase from the 167 pairs counted in 1974 and 1987. Approximately 5 percent of the current population has expanded from the center of the breeding range, and now breeds in the Upper Peninsula of Michigan, Wisconsin and Ontario. In the early fall, they migrate to their wintering ground in the Bahamas.
Prior to modern fire suppression, large natural wildfires frequently burned thousands of acres of jack pine forest on the dry sand plains of Michigan. Most jack pine wildfires killed the older trees and caused millions of seeds to be released. In just a few years, these burned areas were covered with young pine trees. These new stands of young jack pine provided natural breeding habitat for the Kirtland’s Warbler. However, modern fire suppression efforts have substantially decreased the frequency and size of wildfire, significantly restricting the amount of breeding habitat naturally produced for this songbird.
While fire suppression is necessary to protect human life, property and valuable natural resources, it eliminates a natural disturbance factor from the jack pine ecosystem on which many species of animals, plants and insects depend. Each year, the partner agencies involved in Kirtland’s Warbler conservation attempt to mimic the regeneration effects of wildfire by harvesting or burning older jack pine and re-establishing new young jack pine seedlings, for Kirtland’s Warbler and other species found in the jack pine ecosystem.