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The 2009 nesting season is quickly winding down for Wisconsin Kirtland’s warblers, with only a few adults still attending fledglings. This will be the last Update we will send this year, although we plan to compile a season summary to be distributed some time in the next few weeks.
At least 6 Adams County nests have fledged a minimum of 23 young, with the final outcome of another nest not completely known. The female that had been still incubating on Nick's last day of work on July 10 successfully fledged 4 young yesterday. This good news was confirmed through the careful observations of DNR Wildlife Biologist Jon Robaidek. This nest was a renesting effort following parasitism by cowbirds, and one of two nests being attended by the same male. His other nest was expected to fledge approximately July 16, and when this nest was checked yesterday, no fledglings were evident. Given the passage of time since the expected date of fledging, it is quite possible that these birds have dispersed far from the nest site. While we cannot be sure of the fate of the four young previously known to be present, it appears possible that this nest was successful as well. We can say that we did have the successful fledging of 23 to 27 young Kirtland’s warblers from 6 to 7 nests in Adams County in 2009. This far exceeds the nesting production of 2008, and we are optimistic that some of these birds will return to nest in Wisconsin in 2010.
Of the two Kirtland’s warbler males found this year in Marinette County, one bird is no longer on territory and any nesting which may have occurred has apparently been unsuccessful. As of yesterday, the nest at the second site still contained three Kirtland’s warbler nestlings. These young are at least 9 days old today, so can be expected to fledge within the next day or so. This is the first confirmed breeding of Kirtland’s warblers in Marinette County. We are greatly indebted to volunteer Jack Swelstad and retired Forest Service researcher John Probst for their hard work in documenting Marinette County Kirtland’s warblers.
2009 Statewide Census
Cool, rainy weather plagued the first half of the Second Annual Kirtland’s Warbler Census period (June 6-15) again this year. Despite overcast skies, 41 volunteers combed through at least 66 sites in 7 Wisconsin counties (See figure below) looking for the rare bird. Sunshine over the second weekend helped increase our chances of locating singing males.
Although only two surveyors spotted birds, all the participants collected valuable data on habitat characteristics and associated bird species. This information will help direct future survey efforts.
Singing males were reported for two sites in Marinette County and for one site in Adams County (in addition to the traditional Adams breeding site). Subsequent visits to these three new sites revealed that each male had an associated female (see nest updates above for more details). A singing male was also reported at a site in Douglas County, but the report has not been confirmed.
Data has been turned in for 66 of 95 assigned sites to date. About 79% of these sites were determined to be suitable for Kirtland’s warbler nesting based on habitat descriptions and associated bird species data provided by the surveyors. When compared to 2008, the amount of suitable sites surveyed has increased by 29%. We are honing in on the current best sites in the state so that our efforts in the future will be concentrated in the most likely places for birds to occur.
Thank you to all who participated in the surveys and to those who helped with organizing workshops last spring. Your contribution will make it possible to protect new nesting sites and to address conservation and management needs at key sites.