Wisconsin Ecological Services Field Office

Midwest Region


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Green Bay, WI 54229-9565
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Wisconsin Kirtland’s Warbler
2018 Nesting Season Report


close up of male Kirtland's warbler

Photo by Joel Trick.


On April 12th, 2018, the US Fish and Wildlife Service published a proposed rule to remove Endangered Species Act protection for the Kirtland's warbler. Publication of this proposed rule means that the Service believes the Kirtland's warbler no longer faces the threat of extinction and that mechanisms are in place to ensure continued habitat management and cowbird control so that the warbler's recovery will remain intact into the future. The 90-day public comment period on the rule closed on July 11, 2018. Comments received from the public and peer reviewers on the proposed rule are being evaluated and a final determination on the status of Kirtland's warbler is expected in the Spring of 2019.


Kirtland’s warblers nest in young jack pine stands in Michigan and red/jack pine stands in Wisconsin and Ontario, winter in deciduous forests of The Bahamas, and were among the first wildlife in the United States identified as being at risk of extinction. Populations dipped to a low of 167 pairs in 1974 and when the Endangered Species Act was passed into law in 1973, the Kirtland’s warbler was on the initial list of endangered and threatened species. With cooperative efforts among conservation partners, the Kirtland’s warbler population is now estimated to be over 2,300 pairs, more than double the recovery numerical goal. The Kirtland’s warbler population continues to grow and has exceeded the numerical recovery goal for the past 16 years.


In cooperation with Michigan and Wisconsin, a system will be put into place to monitor the species for not less than 5 years. The purpose of this requirement is to develop a program that detects the failure of any delisted species to sustain itself without the protective measures provided by the Act. If, at any time during the monitoring period, data indicate that protective status under the Act should be reinstated, the FWS can initiate listing procedures, including, if appropriate, emergency listing. The proposed rule to delist the Kirtland’s warbler and supporting documents are available on http://www.regulations.gov. In the Search box, enter FWS–R3–ES–2018–0005, which is the docket number for this rulemaking.


The 2018 nesting season marked the 11th year of Kirtland’s warbler documentation and monitoring in Wisconsin and the population continues to increase and geographically expand. On May 8th, Barry Benson (USDA-APHIS) heard a Kirtland’s warbler singing at the Adams County site and proclaimed “They’re back!”. Over the course of the week, many more Kirtland’s were observed and most of the color-banded males occupied the same territories as they held in previous years.


We are grateful for the hard work of our many partners who continue working on projects related to Kirtland’s conservation. These partners include: Kirtland’s site monitors Anna Jocham and Ashley Olah (Adams County), Adelyn Hanchette (Marinette Country), and Jean Haack (Vilas County); The University of Wisconsin; The USFWS Partners Program; Wisconsin Natural Resources Foundation; USDA Wildlife Services; WDNR; USFWS Ecological Services, county forests (Marinette, Vilas, Bayfield, Jackson); US Forest Service; Sand Valley Restoration LLC; and of course you!


Kirtland’s Warbler Season Summary for 2018


• 23 males and 13 females were confirmed in Adams County, 10 males and 3 females in Marinette County, 1 male and 1 female in Bayfield County.


• 16 total nests: 11 nests by 11 pairs in Adams County, 4 nests by 3 pairs in Marinette County, 1 nest in Bayfield County.


• 11 successful nests: 8 in Adams County, 3 in Marinette County.


• 5 nests failed: 3 in Adams County (1 cowbird parasitism, 1 predation, 1 nest had eggs that did not hatch), 1 in Marinette County (unknown cause), 1 nest in Bayfield County (unknown cause).


• A minimum of 42-47 young fledged: 30-35 in Adams County, minimum of 12 in Marinette County.


Kirtland’s Warbler Data for Adams County, 2007-2018


Data in the table include the number of color-banded males confirmed, number of females, number of nesting attempts, successful nests (determined if nestlings fledge the nest), and an estimated number of fledglings.


Year Number of Color-banded Males Number of Females Number of Nesting Attempts Successful Nests Estimated Fledged
2007 8 3 3 unknown unknown
2008 7 5 5 2 (40%) 10
2009 10 10 10 6-7 (60-70%) 23-27
2010 20 11 16 3-5 (19-31%) 12-18
2011 20 11 11 4 (36%) 9-17
2012 20 10 14 4 (29%) 8-13
2013 16 9 12 4 (33%) 13
2014 11 7 8 3 (38%) 8-10
2015 15 14 15 12 (80%) 34-51
2016 18 13 17 7 (41%) 22-23
2017 20 15 16 12 (75%) 38-48
2018 23 13 11 8 (73%) 30-35



Kirtland's Warbler wing feathersKirtland's warbler tail feathers

Ron Refsnider (retired USFWS biologist) determines the age of color-banded Kirtland’s warblers based on
multiple plumage characteristics. Photos show the wing feathers (left) and tail feathers (right) being
examined as part of age determination, Adams County 2018. Photo courtesy of Trina Soyk (USFWS).


Kirtland’s Warbler Data for Marinette County, 2008-2018


Data in the table include the number of color-banded males confirmed, number of females, number of nesting attempts, successful nests (determined if nestlings fledge the nest), and an estimated number of fledglings. 2008 was the first year monitoring occurred for Kirtland’s in Marinette County. The first confirmed breeding (nest was found and monitored until nestlings fledged) occurred in 2009.


Year Number of Color- banded Males Number of Females Number of Nesting Attempts Successful Nests Estimated Fledged
2008 2 1 - - -
2009 2 2 1 1 3
2010 2 1 - - -
2011 1 - - - -
2012 3 - - - -
2013 2 1 1 - -
2014 1 - - - -
2015 3 1 1 1 2
2016 6 3 3 2 10
2017 7 4 4 3 11-15
2018 10 3 3 3 12



Kirtland’s Warbler 2018 State-wide Census Summary

Figure 1. Kirtland's Census Locations by County with Number of Singing Males. Map of Wisconsin counties surveyed in 2017.


• Census period: June 6-27.


• 8 volunteers and 5 DNR staff surveyed suitable habitat in 5 Wisconsin counties (Figure 1).


• 32 singing males were detected during the census period (Figures 1 and 2).


• 10 singing males were recorded in northern counties: 1 in Bayfield County, 9 in Marinette County.


• 22 singing males were recorded at the Adams County site.


• 1 additional male was found in Marinette County after the census period ended.








Figure 2. Singing males recorded during the Wisconsin census 2008-2018. In 2007, 8 males were documented at the Adams site, but a statewide census was not conducted that year.

Graph of singing males recoreded during the Wisconsin census 2008-2018.


Kirtland’s Warbler Adult and Nestling Banding Summary


• A total of 30 Kirtland’s warbler were color-banded in 2018.


• 8 adult males were captured and color-banded in 2018: 5 males in Adams County and 3 males in Marinette


• Of the newly color-banded adult males, 7 were aged to be second-year (SY) and 1 was aged to be aftersecond-
year (ASY).


• 22 nestlings were color-banded in 2018 from 6 nests and all are believed to have fledged successfully.


• ABPI (color-bands Aluminum, Blue, Purple, Indigo) was banded as a nestling in 2014 at the Adams County site. This male was subsequently seen by Ashley Olah and Nathan Cooper (Smithsonian Institute) in the Bahamas in 2015: see 2015 update: https://www.fws.gov/midwest/GreenBay/endangered/kiwa/Updates.html. ABPI was not found in 2015, but was back nesting at the Adams County site in 2016-2018 and had successful nests in 2017 and 2018.


• The Kirtland’s warbler nestling banding project started in 2014 and was expanded in 2016. As a result of the large number of nestlings banded, data indicate robust first-year survival and strong natal site fidelity.


• For example, a Kirtland’s who was banded as a nestling in 2016 with only a numbered aluminum band was recaptured in Bayfield County in 2017 to give him a set of color-bands (Orange, Red, Aluminum, Yellow). This male established a territory in 2017 only 145 meters (159 yards) from where he had hatched (and was banded) in 2016. His territory in 2017 was adjacent to his father's 2017 territory. His 2018 nest was about 250 meters (273 yards) from his 2017 nest, and about 100 meters (109 yards) from where he hatched in 2016.


• Strong natal site fidelity is indicated by the return of nestlings the following year to the area where they were hatched. Due to banding efforts we know that two nestlings banded in Adams County in 2014 (50%), four nestlings banded in Adams County in 2016 (26.7%), one nestling banded in Bayfield County in 2016 (20%), and four nestlings banded in Adams County in 2017 (16.7%) returned in previous years to the site.


Figure 3. The number of color-banded Kirtland’s warblers in Adams County and Marinette County, 2007-2018.

Graph of number of Male KW in Two Wisconsin Counties.




Kirtland's Warbler Playbacks 2018


Playback unit and battery used in northern Wisconsin.

Playback unit and battery used in northern

Wisconsin. Playback units broadcast the Kirtland’s warbler song and are set on a timer to play at various times during the day for a certain duration of time. Playback units were checked twice a week by a field crew. Photo courtesy of Nick Anich (WDNR)

•Audio playbacks used from 2014-2018 have helped to establish Kirtland’s warbler populations at high quality sites in northern Wisconsin.


• Marinette County: Audio playbacks have been successful in Marinette County and as of 2018 playbacks were removed from the site. The site continues to thrive with breeding warblers without the use of playbacks.


• Bayfield County: One pair was attracted to the Bayfield County playback and a nest was found with eggs that had hatched, but further monitoring determined that is was predated and not a successful nest.


•Vilas County: One male was heard (not observed) early in the season at the Vilas County playback site and not detected again at the site.


•For full details of this method and results from 2014-2016 work, see the following publication: Anich NM, Ward MP. 2017. Using audio playback to expand the geographic breeding range of an endangered species. Diversity and Distributions 23:1499–1508. https://doi.org/10.1111/ddi.12635.


• For a full text pdf of the publication, contact: Nicholas.Anich@wisconsin.gov



USDA cowbird trap in Adams County.

USDA Wildlife Services cowbird trap in Adams County, 2017. Photo courtesy of Barry Benson (USDA).

Adams County Cowbird Trapping Summary


• Cowbirds traps are operated and managed by Wildlife Specialist Barry Benson, USDA Wildlife Services APHIS.


• 4 traps were placed in proximity of the Kirtland’s warbler core territory breeding site in Adams County for 10 weeks (from May 2nd until July 2nd).


• 280 cowbirds were captured (246 males, 32 females, 2 juveniles).


• For comparison, a total of 240 cowbirds were caught in 2017, 266 in 2016, 363 in 2015, 110 in 2014, 207 in 2013, 216 in 2012, 166 in 2011, 216 in 2010, and in 2009 a total of 303 cowbirds were caught.


• Cowbird parasitism is present throughout the Adam’s County nest sites, but has not been observed in other nesting areas of Wisconsin (Marinette and Bayfield Counties); therefore, cowbird traps are not necessary in those areas.



Kirtland’s Warbler Field Trips


• 2 field trips to the Adams County site were offered in 2018. May 23 (40 people) through the Natural Resources Foundation of Wisconsin. May 26 (13 people) for Indiana Audubon Society.


• The field trips were attended by a combined total of approximately 53 people.


• The field trips raised funds (approximately $2000) that will be used for Kirtland’s warbler conservation in Wisconsin.


• The field trips were attended by a combined total of approximately 66 people.


• The field trips raised funds (approximately $2000) that will be used for Kirtland’s warbler conservation in Wisconsin.


• Past funds have been used to support the Adams County and Marinette County monitoring crews, an essential part of the Wisconsin Kirtland’s warbler project.


Nest monitors Adelyn Hanchette (left) and Anna Jocham (right) release adult male Kirtland’s after they were color-banded. Marinette and Adams County, 2018. Photos Courtesy of Joel Trick and Trina Soyk(USFWS).



Kirtland's Warbler Habitat Management in 2018


•Douglas County: Work continues to be conducted to thin areas and create openings, and for planning future habitat management projects.


• Bayfield County: Bayfield County Forest continues to implement the Barnes Barrens Management Plan, rotating stands to ensure various ages of pine and open barrens are present on the landscape.


• Marinette County: Marinette County Forest continues to implement the Kirtland’s Warbler Habitat Management Plan and is active in research to investigate methods for enhancing understory and nesting habitat. This work is partially funded by USFWS Partners for Fish and Wildlife Program.


• Adams County: Sand Valley Restoration LLC continues to thin old red pine stands and is currently working on a pine barrens ecosystem management plan.


• Jackson County: Jackson County Forest continues to work on planning for Kirtland’s habitat management. Sites have been surveyed by DNR and USFWS to determine habitat suitability and opportunity for restoration.


University of Wisconsin-Madison, Kirtland's Warbler Research in Adams County, conducted by Graduate Student Ashely Olah, 2016-2018.


Nest Cameras


• Purpose of study: To identify what predators depredate Kirtland’s warbler nests at the Adams County core breeding site.


• Three cameras were deployed on three nests in 2018.


• All chicks successfully fledged from those nests.


• All videos will be reviewed this winter and data will be used to help guide management decisions and actions.


Fledgling Tracking


• Purpose of Study: To determine habitat use of juvenile Kirtland’s warblers.


• Nine transmitters were attached to nine nestlings in 2018 (two nestling each from four nests, and one nestling from one nest).


• All broods were color-banded, including nestlings with the transmitters.


• Fledglings were tracked from 2 - 20 days post-fledging.


• In 2018, four radio-tagged fledglings survived 16+ days out of the nest.


• Preliminary data suggest that fledgling use areas that are larger than areas adults use (male territories).


• Fledglings use areas with greater tree densities than areas they are not observed using.


Picture of Ron Refsnider weighing a Kirtland's warbler and an image of a color banded Kirtland's warbler.

Left Photo: Ron Refsnider weighs a male Kirtland’s warbler after placing color-bands on its legs for identification purposes. Right Photo: A color-banded male Kirtland’s Warbler, Adams County. Photos courtesy of Trina Soyk (USFWS).


Acknowledgements for the 2018 Kirtland’s Warbler Nesting Season


The Kirtland’s warbler 2018 partnership includes the Wisconsin Department of Natural Resources: Davin Lopez, Nick Anich, Richard Staffen, Carly Lapin, Amy Staffen, Aaron McCullough, Caroline Ward, Jon Robaidek, Robert Hansen, Michele Woodford, Ryan Magana, Jill Nemec, Mark Braasch, Ron Gropp, Adelyn Hanchette, Anna Jocham, and volunteer Jean Haack; U.S. Fish and Wildlife Service: Sarah Warner, Trina Soyk, Jeff Hemming, and retired biologists Joel Trick and Ron Refsnider; U.S. Fish and Wildlife Service Partners Program: Gary VanVreede and Mark Pfost; U.S. Department of Agriculture Wildlife Services: Barry Benson; property owners: Sand Valley Restoration LLC, Meteor Timber, Wisconsin Trapshooting Association, and Jackson, Marinette, Bayfield, Douglas, and Vilas County Forests; University of Wisconsin researchers: Ashley Olah, Dr. Anna Pidgeon, and Zoe Osberg; and many volunteers. The information in this report was compiled and written by Sarah Warner, Trina Soyk, and Davin Lopez. Graphs and figures were made by Rich Staffen and data were provided by nest monitoring, surveys, census, and banding efforts.


There are many enthusiastic and dedicated partners that we wish to thank for making the season such a success. We are grateful for the efforts from the following collaborators: Sand Valley Restoration LLC allowed us to use their lands to conduct monitoring, banding and cowbird trapping. Meteor Timber and Wisconsin Trapshooting Association supported monitoring activities on their properties. Bayfield, Marinette, Vilas, and Jackson County Forests continue to be extremely supportive by allowing monitoring, developing plans for the management of Kirtland’s habitat, and conducting habitat improvement projects.


The U.S. Department of Agriculture (USDA) Wildlife Services managed cowbird traps, with the efforts of Wildlife Specialist Barry Benson. The Natural Resources Foundation of Wisconsin (NRF) funded nest monitoring and offered field trips that provided outreach for public engagement and generated funding to cover housing costs for the nest monitors. Barry Benson, Jon Robaidek, Rich Staffen, Amy Staffen, Sarah Warner, Mark Pfost, Jens Jensen, Gene Bader, Anna Jocham, and Ashley Olah were trip leaders for the NRF field trips.


The WI Department of Natural Resources Natural Heritage Conservation (NHC) Bureau and the U.S. Fish and Wildlife Service provided funding to support the work of Davin Lopez for project coordination, management, and logistical support. The NHC provided funding to Rich Staffen, Amy Staffen, Nick Anich, and Carly Lapin for project support. Aaron McCullough, Robert Hanson, and Caroline Ward were financially supported by the DNR Bureau of Wildlife Management. The U.S. Fish and Wildlife Service (USFWS) Ecological Services Minnesota/Wisconsin Field Office and the DNR contributed funding to help offset the costs of cowbird trap operation.


USFWS Ecological Services provided funding to support the work of Sarah Warner and Trina Soyk that involved project coordination, management, and banding efforts and Jeff Hemming for website design and technical support. The USFWS Partners for Fish and Wildlife Program biologists Mark Pfost and Gary VanVreede provided funding, logistical support, and efforts for habitat projects at the Adams and Marinette County sites. We thank the members of the Kirtland’s Warbler Conservation Team (former Recovery Team) for their efforts to protect and conserve the Kirtland’s warbler and for their input and guidance on various aspects of the Wisconsin project.


This year our outstanding Kirtland’s warbler monitors were Anna Jocham, Adelyn Hanchette, Ashley Olah, and Zoe Osberg. Jean Haack graciously donated her time to run playback units in Vilas County. Barb and Ed Saloga provided housing for the Marinette County nest monitor. Ron Refsnider and Joel Trick contributed their expertise to make the color-banding efforts a success and the USFWS covered costs associated with their travel.


The generous efforts of numerous enthusiastic birders allowed us to survey for Kirtland's warblers for the state-wide census at many Wisconsin sites. We wish to thank Jean Haack, Rob Baller, Tim Collins, Donna Roche, Jack Swelstad, Mike Carlson, Ashley Umlauf, and Dave Wiemiller for their survey assistance. The U.S. Forest Service, Chequamegon-Nicolet National Forest also conducted surveys for Kirtland’s. Pete Villas, Marinette County Forest Administrator, provided assistance in identifying potential suitable habitat to survey for Kirtland's warblers, as well as conducting habitat understory research projects. We are grateful to Nancy Livingston for providing housing for nest monitor Zoe Osberg.


Our work with Kirtland’s warblers in Wisconsin generates a great deal of interest, and our success is a tribute to the many individuals and organizations involved in the project. We are grateful to receive tremendous support from the public and conservation community. As has been the case throughout the life of the project (11 years), we continue to be dependent upon the critical contributions of our numerous partners—thank you!


Sarah Warner
U.S. Fish & Wildlife Service
505 Science Drive
Madison, WI 53717
608-238-9333 ext. 130

Davin Lopez
Wisconsin Department of Natural Resources
101 S. Webster Street - ER/6
Madison, WI 53703



Kirtland's Warbler in Wisconsin - Updates

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Last updated: June 28, 2019