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Adams County Monitoring
There have been few changes at the Adams County nesting site in the past week. Most Kirtland’s warbler females are probably laying and starting incubation at this time. Nick has continued his observations to confirm nesting, and so far has found five nests, two of which were noted to contain cowbird eggs. There is one new unbanded male at the site, so the total number of birds known to be present is now 17 males and 6 females. In addition to these totals, the banded male that returned to another Adams County site now has a mate, and this week we were able to confirm that she has a nest with a full clutch of five eggs.
Marinette County Banding
Yesterday we made an effort to capture and place color bands on Kirtland’s warblers recently reported from three separate Marinette County sites. At the first site we targeted, we were unsuccessful in locating the bird reported here last week, despite an abundance of great looking habitat. We moved on to another nearby site, and managed to quickly capture and band a male Kirtland’s at the same site where nesting occurred last year. We then traveled to the third site, where 3 different birds were observed as late as last Thursday. Despite considerable effort and searching, we could not locate any of these birds either. Given that the habitat was not ideal, it seems plausible that these birds have decided to look for a better site. Past research in Michigan has documented significant movements of color-banded birds during the nesting season.
USDA Wildlife Specialist Barry Benson reports that over the past week, he removed an additional 12 cowbirds from the three cowbird traps. Through June 4, a total of 201 cowbirds have been captured, consisting of 137 males and 64 females. This week, only one of the 12 birds captured was a female. Hopefully, this indicates that few females are present to parasitize Kirtland’s warbler nests. We plan to continue cowbird trapping for about two more weeks.
Annual Kirtland’s Warbler Survey
A crew comprised of 32 citizen volunteers, 6 staff, and 1 contractor continues to comb the jack pine stands of Wisconsin in the hopes of spotting a male Kirtland’s warbler. The annual survey began on May 15, which was about three weeks prior to the official census period of June 6-15. This year’s early start date was chosen because birds are more vocal and visible prior to the onset of nesting and are therefore easier to detect in May than in June. The drawback to searching early is that birds found before June 6 must be relocated during the census period in order to be included in Wisconsin’s 2010 population estimate. In some cases, the relocation is proving to be a bit challenging.
So far, we have received reports from 18 surveyors who visited 73 sites in 7 counties (Douglas, Bayfield, Vilas, Oneida, Marinette, Adams, and Jackson). Five males were recorded at three sites in Marinette County by Jack Swelstad, John Probst, and Jon Motquin, but only one of these was relocated yesterday (see banding update). The male that nested at our second Adams County breeding site in 2009 was found again at the site by Paul Charland and Rachel Samerdyke in late May. We also have two as yet unconfirmed sightings: one in Bayfield County and the other in Jackson County. Over the next few days, we hope to get more information on each of these sightings.
The crew will be working hard through June 15 to complete all 89 assigned sites, to verify presence of the unconfirmed males, and to relocate birds that were found before June 6. Also, some volunteers plan to visit their sites for a second or third check in order to increase the degree of certainty on the presence or absence of singing males. Anyone finding a Kirtland’s warbler is asked to contact either Joel or Kim at the e-mails and telephone numbers listed below.