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Wisconsin Kirtland's Warbler 2008 Nesting Season Summary
The following is a brief summary of Kirtland's warbler activities conducted in Wisconsin in 2008. 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). Kims' participation in the project was funded by the Natural Resources Foundation of Wisconsin.
Kirtland's warbler field observations began on May 14, when at least two singing males were present at the Adams County site. The Wisconsin DNR hired UW-Green Bay wildlife biology graduate student Jennifer Goyette as a full time monitor to track activities at the Adams County site, and she began continuous field observations on May 19. Hiring Jennifer proved to be one of the best decisions we made all year, as she demonstrated exceptional skill in documenting home territories, finding nests, and determining their outcomes.
Jennifer was able to establish the presence of at least 7 singing males by May 29, including one bird that was already color banded. All of these birds were eventually captured and all 6 unbanded birds were given unique combinations of color bands. On June 25, another unbanded male appeared at the Adams County site, but this bird was never captured and banded.
The first female was observed at the site on May 19, and additional females were found as the season progressed through observations in each of the territories being defended by males. During the course of the season five separate nests were found. One nest was predated prior to hatching, and of the remaining four nests, one nest fledged two brown-headed cowbird young, one was apparently predated approximately one week after hatching, and the remaining two nests each fledged five young.
Cowbird traps were installed by U.S.Department of Agriculture (USDA) -Wildlife Services at the Adams County nesting site on April 15, and operated through June 20. Trapping was conducted by USDA-Wildlife Services and during the period of trap operation, over 300 cowbirds were known to be captured.
Banding operations in Wisconsin were conducted by retired FWS biologist Ron Refsnider on June 9, 10 and 19, with the assistance of Joel Trick and Jennifer Goyette. These efforts resulted in the capture of a total of 9 different Kirtland's warbler males, one of which had been previously banded in the Bahamas on March 20, 2008. Unbanded birds were banded with aluminum FWS bands and three separate color bands, with six birds banded at the Adams County sites, and two other birds at separate sites in Marinette County.
WSO Field Trip
On May 31, we conducted a Kirtland's Warbler Field Trip for members of the Wisconsin Society for Ornithology (WSO). Participation was determined through a drawing, and attendance was limited to 72 participants. All field trip participants were able to view a singing male Kirtland's Warbler. Feedback we received following the trip was all extremely positive, and WSO is already looking forward to and planning for a repeat of this field trip in 2009.
A statewide survey of potentially suitable Kirtland's warbler habitat was organized by Kim Grveles of the Wisconsin DNR, and conducted with the aid of numerous volunteers. The Surveys were conducted at numerous sites in 11 different Wisconsin counties. Surveys were hampered by adverse weather conditions over much of the period, but results have highlighted several areas to concentrate our efforts next year.
Volunteers discovered two singing male Kirtland's warblers at two sites in Marinette County, and both birds were captured and banded. On July 9, an additional single male responded to a tape and was observed at close range in Douglas County. Four additional survey teams reported hearing and/or seeing male Kirtland's Warblers at three sites in Vilas County, three sites in Jackson County, and two other sites in Marinette County. Unfortunately, we were unable to confirm any of these additional observations during subsequent visits to the sites.
On June 24, a male Kirtland's warbler responded to a tape during a survey conducted on the Chequamegon-Nicolet National Forest in Bayfield County. This bird was observed at close range and was closely associating with another bird which appeared to be a female Kirtland's warbler. The person conducting this search was hired by the National Forest specifically to search for Kirtland's warblers, but was not part of our volunteer survey effort. Repeated visits to this site failed to result in any subsequent observations.
The success of our activities in Wisconsin in 2008 is very much a result of the cooperative effort by numerous participants who contributed to the project. Plum Creek Timber Company has graciously allowed us to use their lands to conduct monitoring and cowbird trapping, and provided great support and information at our WSO Kirtland's Warbler Field Trip. The Wisconsin Department of Natural Resources hired the full-time monitor which allowed us to collect detailed nesting data at the Adams county sites. The U.S. Department of Agriculture -Wildlife Services constructed and operated cowbird traps, and the Natural Resources Foundation of Wisconsin and the U.S. Fish and Wildlife Service Partners for Fish and Wildlife Program provided funding assistance to help offset the costs of cowbird trap operation. The Natural Resources Foundation of Wisconsin provided funding to organize and conduct statewide surveys. Numerous County Forest Administrators provided assistance in identifying those land areas that they manage which could be suitable habitat to survey for Kirtland's warblers, and the generous efforts of numerous enthusiastic birders allowed us to look for Kirtland's warblers at many Wisconsin sites.