No Longer An Endangered Species, Kirtland’s Warbler Population Growing in Michigan
(Michigan DNR, Nov. 25, 2021)
Michigan – State and federal agencies and droves of volunteers have partnered to count Michigan’s Kirtland’s warbler population.
The agencies recently announced that surveys conducted in June show the small songbirds have continued to flourish since their October 2019 removal from the federal list of endangered species.
“The power of partnership continues to yield excellent results for the Kirtland’s warbler after coming off the endangered species list,” said U.S. Fish and Wildlife Service Regional Director Charlie Wooley. “Recovery of this beloved species required a strong, creative set of partners, and that spirit continues into the future with agencies, organizations and private entities working together locally, nationally and internationally. I’m confident this strong partnership will secure the long-term future of this bird.”
With the June survey results now tallied, the Kirtland’s warbler global population is estimated at 2,245 pairs, which is more than double the 1,000-pair recovery goal for the species – which has been exceeded over each of the past 20 years.
Researchers survey nesting areas, listening for singing males advertising and defending nesting territories. Each male found is presumed to have a mate, so the number of males also indicates the number of pairs.
Kirtland’s warblers build nests on the ground, only in young, dense stands of jack pine in Michigan, Wisconsin and Ontario. This habitat was historically created by large wildfires. Today, wildfires are suppressed, and the nesting habitat is created by harvesting mature jack pine and planting jack pine seedling in the logged areas.
This year’s Kirtland’s warbler counts took place in jack pine nesting habitat situated across lands managed by the Michigan Department of Natural Resources, U.S. Forest Service, and U.S. Fish and Wildlife Service. Nearly all the world’s Kirtland’s warbler population nest in Michigan’s northern Lower Peninsula.
In 2017 and 2019, partial surveys were completed. This year’s thorough census was the first full count of Kirtland’s warbler since 2015, when 2,365 singing males were counted. This is believed to represent ALL the adult males of the entire global population of this highly localized bird species.
“Recovering a species as imperiled as the Kirtland’s warbler wasn’t easy,” said Brian Bogaczyk, Regional Threatened and Endangered Species Biologist for the USDA Forest Service Eastern Region. “The US Forest Service is honored to play a part in the Kirtland’s warbler comeback, an incredible success story that’s a great example of what we can achieve with strong partnerships. We must continue to invest in creating habitat for this disturbance-dependent species to thrive, and the Forest Service is committed to doing our part in the future.”
More specifically, 1,114 singing males were located on the Huron National Forest – representing a 9% increase over the number counted in 2019 – while 994 singing males were found on lands managed by the DNR and U.S. Fish and Wildlife Service in the northern Lower Peninsula.
In addition, two singing males were found in Lake County on the Manistee National Forest in jack pine not established for Kirtland’s warbler breeding habitat. This was the first time the birds have been found on the Manistee National Forest since 1977.
“The number of singing males was above what we expected,” said Phil Huber, Wildlife Program Manager for the Huron-Manistee National Forests in Cadillac, MI. “It’s really gratifying to see this species doing so well, especially compared to the population lows we observed in the 1970s and early 1980s when 200 singing males was the average. The recovery of this species has been a decades long effort by many dedicated individuals.”
In the Upper Peninsula, a record number of Kirtland’s warblers were recorded by census participants. Previous counts recorded 37 singing males in 2015, 44 in 2017 and 40 in 2019. This year, 67 singing males were found across the Upper Peninsula, including 42 on the Hiawatha National Forest and 25 on state forest lands, with 22 of those situated within recovering jack pine forests burned in the 21,069-acre Duck Lake Fire of 2012.
“Expansion of Kirtland’s warblers into new areas, and in greater numbers, is good news for the future of the species in Michigan,” said DNR Director Dan Eichinger. “From the Kirtland’s Warbler Alliance and American Bird Conservancy to our state and federal partners in the Great Lakes region, the effort and teamwork committed to the recovery of this species continues to pay great dividends.”
In addition to the birds found in Michigan, Wisconsin surveyors detected 39 singing males, largely in central Wisconsin’s Adams County. This is an all-time high for Wisconsin, which has been seeing ever-increasing numbers since first being detected in 2008. Also, surveyors in Ontario detected 22 singing males, also representing an all-time high there since surveys began.
Kirtland’s warbler surveys have been conducted in Michigan since 1951. The species was among the first animals included when the Endangered Species Act was passed in 1973. Populations sunk to a low of 167 pairs in 1974 and 1987 before mounting a gradual recovery.
Aiding greatly in that return were cooperative efforts between state and federal agencies, along with conservation groups, to conserve and expand suitable jack pine habitat and control brown-headed cowbirds. Cowbirds are nest parasites that lay their eggs in the nests of Kirtland’s warblers and other bird species. The larger cowbird chicks out-compete warbler chicks for food, which causes them to die, while the warbler parents unknowingly raise the cowbird chicks.
By 2001, the number of Kirtland’s warbler pairs in Michigan had surpassed 1,000, while the places the birds were located expanded to include the U.P., Ontario and Wisconsin. The birds migrate to and overwinter in The Bahamas.
The Kirtland’s Warbler Breeding Range Conservation Plan was developed in 2015 and is now the guiding management strategy for the species. Additionally, funding and other commitments to habitat management and cowbird control are in place to ensure continued conservation actions in the absence of Endangered Species Act protections.
In addition, the Kirtland’s Warbler Conservation Team has replaced the Kirtland’s Warbler Recovery Team established under the Endangered Species Act. Today, the Conservation Team preserves institutional knowledge, shares information and facilitates communication and collaboration among agencies and partners to maintain and improve Kirtland’s warbler conservation.
The current make-up of the team includes representatives from the US Fish and Wildlife Service, US Forest Service, Michigan Department of Natural Resources, Wisconsin Department of Natural Resources, USDA-Wildlife Services, Canadian Wildlife Service, Huron Pines, Kirtland’s Warbler Alliance, American Bird Conservancy and California University of Pennsylvania.
The Kirtland’s Warbler Conservation Team is an integral part of post-delisting monitoring efforts and provides an important forum for sharing information, coordinating management efforts and ensuring that effective adaptive management occurs. The Kirtland’s Warbler Alliance is a non-profit organization dedicated to helping ensure needs of the species are addressed.
Find out more about Kirtland’s warbler recovery, delisting, tours and more.