Kirtland's warblers return to nest; More birds and more habitat are good signs
News Release Published: May 24, 2012 by the Central Office
Contact(s): Kim Grveles, DNR avaian ecologist, (608)264-8594
Editor's note: The headline has been updated to more accurately reflect the fact that while more Kirtland's warblers have been seen in Wisconsin than before, bird experts won't have a final count and can't declare a new record until later this summer when they can sort out which unbanded birds might have been seen more than once in different locations.
MARINETTE COUNTY – State and federal bird experts are singing a happy tune this May as a growing number of Kirtland’s warblers, a federally endangered songbird, alight in the jack pine forests of Wisconsin and get ready to build their nests.
“More birds are present in Wisconsin than we’ve ever recorded before and they’re expanding their habitat,” says Kim Grveles, a Department of Natural Resources avian ecologist. “They moved into habitat next to the main breeding site, which we see as a good sign that the population can expand by having more habitat available for breeding.”
Also, a Kirtland’s warbler sighted in Marinette County last week has been confirmed as one that was banded at the same site in the previous year, the first documented return to a Marinette site.
“That shows site fidelity and now all we need is for a female to come along!” says Grveles.
It’s all great news for a species that until 1995 was found almost exclusively in the northern Lower Peninsula of Michigan and was struggling to recover from a steep decline in populations in the 1960s and 1970s due to habitat loss and trouble from the brown-headed cowbirds.
The Kirtland’s warbler was placed on the federal endangered species list about 40 years ago, when its population dropped to about 300 birds. DNR is now proposing to add the species to the state endangered species list because its numbers, while growing in Wisconsin, are still very small.
Starting in the late 1990s, the protections and efforts made under that federal law enabled the Kirtland’s warbler to start expanding its breeding territory to Wisconsin, Michigan's Upper Peninsula and Ontario. The warblers have been observed in several counties in Wisconsin, and nests have been confirmed in Adams and Marinette counties.
To help increase Kirtland's warblers in Wisconsin, DNR, the U.S. Fish & Wildlife Service and other partners now conduct annual surveys in seven counties to listen and look for the birds, monitor nests in Adams County where breeding sites have been found, and set traps to keep cowbirds away from the warblers' nests. Cowbirds lay their eggs in the nests of songbirds including Kirtland’s warblers. The warblers are unable to recognize cowbird eggs or chicks as different from their own young. Cowbirds hatch earlier, are larger, and more aggressive at begging for food than warbler chicks, which results in the Kirtland’s warbler parents raising a cowbird or two at the peril of their own brood.
The partners also are working to maintain and expand the mix of 5- to 20-year-old jack pine trees and barrens necessary by planting the tree species. Historically, such habitat depended on fire, Grveles says.
More information on the bird, restoration efforts and how to get involved can be found on DNR's featured Kirtland's warbler page as part of its Celebrating 40 years of protecting Wisconsin's natural heritage. Go to dnr.wi.gov and search for "ER 40."
Warbler work comes home to roost -- in a good way
Such efforts are coming home to roost in 2012 -- in a good and big way, as more than 20 volunteers search for Kirtland’s warblers in the jack pines of seven Wisconsin counties from May 15-June 15.
On May 11, 2012, the first day of surveying, volunteer monitors confirmed the presence of at least four male Kirtland’s warblers at the Adams County nesting site. At least three birds had bands on their legs, indicating and demonstrating what Grveles called, “site fidelity” – the ability of a bird to return to its nesting territory.
On May 15, volunteer Daryl Christensen was surveying young pine habitat in Adams County and reported that as many as 30 males were present at that site, including quite a few that were unbanded.
"Twenty years ago, I saw my first (and I thought perhaps, my last) Kirtland's warbler in a vast pine stand in Mio, Michigan,” says Christensen, a Montello resident. “Little did I know then, that one day I would be surrounded by singing Kirtland's warblers less than an hour from my home in central Wisconsin. After all, it isn't every day that you get to be serenaded by a federally-endangered species at 6 o'clock in the morning!”
On May 16, volunteer Jack Swelstad found the Marinette male with the colorband, and the next day, Swelstad heard Kirtland’s warblers singing at two other sites. Weekly updates are posted on the U.S. Fish & Wildlife website.
“We’re very lucky we’ve got such skilled people doing the surveys,” Grveles says. “It’s very challenging work – following a little warbler that doesn’t sit still for very long and trying to read the bands on its legs.”
Christensen, for example, has been doing bird surveys for DNR, the U.S. Fish & Wildlife Service, International Crane Foundation and Wisconsin Society for Ornithology for four decades.
He and other volunteers are trying to get GPS readings to find out the approximate location of the territories of the birds that do not yet have bands. In coming weeks, DNR and USFWS staff and volunteers will set “mist nets” near the birds’ territory, run recordings of the female birds, and hope to draw amorous males into the nets where they will be quickly banded, their information recorded, and then released.
DNR, USFWS and USDA wildlife specialists have been setting cowbird traps at the Adams County nesting site since April 23. They have captured 160 cowbirds and will continue operating the nets through late June. The warblers will have nested and their young hatched and fledged around that time, adding to the growing population of a bird that measures just 5 ˝ inches long and weighs under a half ounce.
“I've been interested in birds all my life and have worked on many projects in the past 40 years,” Christensen says. “I volunteer because there is a need to learn as much as we can about these birds while at the same time, establishing an alternate population away from the Mio, Mich., colony in case a disaster would hit that area. And there is a need right now to save money and our biolgists and ecologists are stretched pretty thin for time and dollars, so I'm glad I can help out.”
Comeback champ for May a retired federal biologist
Volunteer Ron Refsnider was named the Comeback Champ for May his work to capture and band Kirtland's Warblers in Wisconsin.
Refsnider was honored by DNR Secretary Cathy Stepp at the state Natural Resources Board meeting May 23 in Madison for his role in efforts to help restore the federally endangered songbird.
Refsnider, a retired U.S. Fish & Wildlife Service biologist, had worked on Kirtland's warbler conservation in Michigan in the 1990s. Stepp noted that for five years, Refsnider has donated his equipment, his time and expertise to mark the birds for study. His banding makes it possible for DNR to track the movements of males, to define their territories, to document their nesting outcomes, and to measure their population growth, she said.
Populations of the Kirtland’s warbler, at 300 birds when the species was listed as a federally endangered species in the 1970s, has now recovered to about 3,600 birds.