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The following is a brief summary of Kirtland's warbler activities in Wisconsin in 2011. Planning and coordination for these activities were conducted by Joel Trick of the U. S. Fish and Wildlife Service and Kim Grveles of the Wisconsin Department of Natural Resources (DNR).
In 2011 Sam Jonas served as the primary monitor at the Adams County sites we have monitored for the past four years. Sam monitored Kirtland’s warblers at these sites from May 16 to July 14, with at least six males already present on his first day of work. New arrivals increased this total to at least 15 males by the end of May and a total for the season of 18 males at our main breeding site. The first female was observed on May 17, and a total of 11 females were eventually found during the season.
Caitlynn Nemec began work as our second monitor on June 1, assisting Sam in coverage of our main breeding site, providing coverage at other sites around the state, and also monitoring the satellite Adams County site where Kirtland’s warblers nested in 2009 and 2010. This year we had up to three males present at this site, including one bird that had been briefly observed here in late summer of 2010. A single female was present for a short time, but no nesting was detected at this site in 2011.
For the 2011 breeding season, we documented a total of 20 male and 11 female Kirtland’s warblers in Adams County. Similar to last year, we observed a very high return rate, with 16 of the 18 color-banded males present in Adams County in 2010 returning in 2011.
This year we were very cautious in our monitoring of nests, and did not approach any nests closely until near fledging. Hence, we have no information on the level of nest parasitism by brown-headed cowbirds, and our knowledge of specific nest outcomes is somewhat limited.
Though our evidence is scant, we feel that the protracted, cold spring and heavy rain adversely affected Wisconsin Kirtland’s warbler nest success. Of the 11 documented nesting attempts, two were renests following failure of first nests. Three nests failed due to known or suspected predation and three were abandoned for unknown reasons. At another nest, heavy rain and cold temperatures are thought to have contributed to the death of four nestlings found dead near their nest just prior to fledging. At least four Adams County Kirtland’s warbler nests were successful in 2011, fledging an estimated 9 to 17 young.
A single Kirtland’s warbler male was found May 29 by Daniel Schneider at another Marinette County site, but was not present when we visited the area for banding on June 1.
On May 20, a single Kirtland’s warbler male was found on Bayfield County Forest land by DNR wildlife biologist Steve LaValley. Subsequent site visits by multiple individuals failed to relocate this bird. This is the same site where a single bird was found in 2010, and the area has an abundance of apparently suitable habitat. It is possible that this was the same bird that was later found at a nearby site in Douglas County.
On June 9, Robbye Johnson found a single Kirtland’s warbler male in Douglas County, approximately 6 miles west of where a Bayfield County bird had been seen in May. This bird remained in the area through early July, and was seen by multiple observers. On July 6, we visited the site and were able to successfully capture and band this bird. No evidence of a female or nesting was observed at this location.
On May 25, Darwin Wile observed a female Kirtland’s warbler that responded to a recording near Boulder Junction. A subsequent visit in early June failed to relocate this bird. This is the same site where birds were reported in 2008, but never confirmed.
In 2011, Kirtland’s warblers were recorded in five counties in Wisconsin, and we documented a minimum of 22 male and 11 female Kirtland’s warblers present in the state. Of a total of 11 recorded nesting attempts, 4 nests were known to be successful, fledging an estimated 9 to 17 young.
A total of three brown-headed cowbird traps were installed by U.S. Department of Agriculture (USDA) -Wildlife Services at the Adams County nesting sites, and operated for 11 weeks, from April 18 through July 1. USDA Wildlife Specialist Barry Benson again operated the traps, capturing 114 males and 52 females for a grand total of 166 cowbirds removed from the site in 2011. This compares to a season total of 216 captured through 9 weeks of trapping in 2010, and 303 for the same period in 2009. The low numbers of cowbirds trapped this year was also observed by the trapping program in Michigan, and thought to be due to a delayed migration caused by our cool, late spring.
Adams County Banding operations in Wisconsin were again led by retired FWS biologist Ron Refsnider. On June 1 we successfully captured and color-banded each of the three unbanded males present at our main Adams County nesting site. In the process of targeting these birds, we incidentally captured a single female, which we also banded. Another unbanded male appeared at the site in late June, and we captured and banded this individual on June 29.
Marinette County On June 1 we visited two sites in Marinette County where birds had been reported, but were able to find only one of these birds, which we successfully captured and banded.
Douglas County On July 5 we sent Caitlynn up to Douglas County to check on a bird that had been seen at this site beginning June 9. After she confirmed that the bird was still present, we mobilized a banding operation, and were able to successfully capture and band this bird on July 6.
A total of six male Kirtland’s warblers were captured and banded in Wisconsin in 2011, four in Adams County, one in Marinette County, and one in Douglas County. One female was also banded at our main site in Adams County. Notably, of the 18 banded males present in Adams County in 2010, 16 were documented to return
in 2011, a survival rate of 89%.
Of the four male Kirtland’s warblers we banded in 2008-2010 in Marinette County, none have returned to Marinette County in subsequent years. However, of note is that one Marinette County male that we banded in 2008 was sighted on the Raco Plains in the eastern Upper Peninsula of Michigan in both 2010 and 2011.
A statewide survey of potentially suitable Kirtland’s warbler habitat was conducted between 15 May and 15 June by 23 volunteers plus seven agency staff who searched 83 sites in seven Counties (Washburn, Douglas, Bayfield, Vilas, Marinette, Adams, and Jackson). During the survey period, singing males were found at three sites in Marinette County, at the second breeding site in Adams County, one site in Douglas County, and one in Bayfield County.
Wisconsin’s count of Kirtland’s warblers observed during the official Michigan Kirtland’s Warbler Census period of June 6-20 was 21 singing males distributed as follows: Adams County 19, Marinette County 1, Douglas County 1. Additional birds observed outside of the census period include the following: Adams County 1, Marinette County 2, Bayfield County 1. One of these additional birds was banded, while the remaining birds were not. Because the unbanded birds were observed on various dates in multiple locations, we cannot confirm how many birds were actually present in Wisconsin in addition to the 21 reported for the census period. However, including the known banded bird, a minimum of 22 Kirtland’s warbler males were present in Wisconsin in 2011.
This year we again organized field trips for members of the Natural Resources Foundation of Wisconsin (NRF). NRF has been our projects’ single largest supporter, and we enjoy offering the opportunity to view Kirtland’s warblers to loyal NRF members. We held field trips on May 20 and 21, and between the two days we accommodated 64 participants, including attendees from 9 states other than Wisconsin: Illinois, Iowa, Minnesota, North Dakota, Colorado, Wyoming, Massachusetts, Texas and California. All field trip participants were able to see and hear a singing male Kirtland’s warbler.
Our work with Kirtland’s warblers in Wisconsin continues to generate a great deal of interest, and our success is a tribute to the many individuals and organizations involved in the project. As has been the case throughout the life of the project, we continue to be dependant upon the critical contributions of our numerous partners.
Plum Creek Timber Company again allowed us to use their lands to conduct monitoring, banding and cowbird trapping, and provided great support and information at our NRF Kirtland's Warbler Field Trip. The U.S. Department of Agriculture-Wildlife Services contributed resources to fund operation of cowbird traps, with the efforts of Wildlife Specialist Barry Benson again proving essential to the nesting success of Wisconsin Kirtland’s warblers.
The Natural Resources Foundation of Wisconsin provided the bulk of project funding to support Adams County monitoring and banding. NRF also funded Kim Grveles involvement, which included her share of project coordination, public outreach and education, coordination with other DNR programs to promote management of jack pine barrens for Kirtland’s warbler, and especially volunteer coordination and organization of statewide surveys.
The U.S. Fish and Wildlife Service contributed funding through the Partners for Fish and Wildlife Program to help offset the costs of cowbird trap operation, and Endangered Species Act Section 6 funds partially funded Kim’s involvement in the project.
This year we again had the services of two capable field biologists as Kirtland’s warbler monitors, Sam Jonas and Caitlynn Nemec. We hope they enjoyed the experience as much as we enjoyed working with them, and we wish them both the best of luck in future endeavors.
Adams County tree farmer Nancy Livingston once again opened her home to us and provided lodging for our monitor, as she has for the past three years. Nancy has met this critical need in each year of the project to date, and we are deeply grateful for her incredible hospitality.
Ron Refsnider contributed his time and expertise to make our color banding efforts a great success. Ron has demonstrated a high level of skill in not only capturing and banding warblers, but also in working with our cooperators to provide them with a memorable experience.
A number of County Forest Administrators provided assistance in identifying potential suitable habitat to survey for Kirtland's warblers. The generous efforts of numerous enthusiastic volunteer birders allowed us to survey for Kirtland's warblers at many Wisconsin sites. Eagle Optics generously provided binoculars for our monitor at a reduced cost.
In addition to those named above, individuals contributing to the project in 2011 included volunteers Kurt Brownell, Joan Campbell, Rich Campbell, Erik Collins, Mark Collins, Tim Collins, Donna DePape, John Hager, Kirk Hager, Rob Heagle, Dan Jackson, Robbye Johnson, Karen Karash, Jim McCrady, Mark McInroy, Marlene Nelson, Joe Palzkill, John Probst, Michael and Christine Sabyan, Rebecca Schroeder, Paul Schwalbe, Glenna Schwalbe, Ingrid Stephan, Jack Swelstad, Troy Walters, Tom Underwood, Dave Weimiller, and Darwin Wile, Carol Bocetti, Steve Sjogren, Daniel Schneider, U.S. Fish and Wildlife Service staff Paul Charland, Rachel Samerdyke and Lisa Maas, and Wisconsin DNR staff Nick Anich, Ryan Brady, John Dadisman, Steve LaValley, Tom Prestby, Jon Robaidek, Dave Troester, and Michelle Windsor.
Joel A. Trick