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Adams County Report
Since our previous update, our monitor Sam has documented the arrival of an additional three males and three females, bringing the total number of Kirtland’s warblers known to be present at our main Adams County nesting site to 17 males and 11 females. The three males arriving this week included another unbanded male that was first seen on Wednesday (see below), and two more of the banded males that were present last year.
Sam has observed a number of females that appear to be checking out prospective nest locations. Though no nests have yet been found, our observations over the past few years indicate that this is the time when the first nests are being initiated. It seems likely that nest initiation may be delayed this year due to our cool, late spring.
This Wednesday marked the first day of work for our second warbler monitor, Caitlynn Nemec. Caitlynn will focus her efforts on the multiple sites where birds have been observed throughout the state, in particular Marinette, Bayfield and Vilas counties. She will also assist in monitoring at the main Adams County breeding site, and survey other sites in the area that may be suitable for occupation by Kirtland’s warblers, including the other Adams County site where birds have bred successfully each of the past two years. In fact, when she checked this site today, she was able to locate the same banded male that was there in 2009 and 2010. Including this bird, we have now documented the return of 15 of the 18 banded males known to be present in Adams County in 2010, an 83% survival rate.
We conducted our 2011 banding operation on Wednesday June 1, with our effort again spearheaded by volunteer bander Ron Refsnider. The banding crew met at the site at 7:00 AM, with plans for capture of the two unbanded males that Sam had located over the past few weeks. Upon arrival, we were surprised to encounter a newly arrived Kirtland’s warbler, and a quick check confirmed that this bird was also unbanded. Sam was able to guide us to the territories of each of the unbanded males, and by the end of the morning we had successfully captured and banded all three birds. Having these birds marked with their own color bands will allow Sam to more effectively map their individual territories and greatly facilitate monitoring.
We also attempted to recapture the banded male that has lost one of its color bands. Despite several efforts, we were unsuccessful in capturing this bird, although in the process we did manage to accidentally net his female, only the second female we have ever caught and banded. We may try for the male again during a future banding trip, as we still would like to replace his lost band and confirm his identity. We are 99% sure we know his identity as he is occupying the same territory as last year, but if possible would like to capture him and check his band number.
After completing our Adams County banding, we then traveled to northern Marinette County to make a try for several birds reported from this area. We did manage to find and band one of the birds found by volunteer Jack Swelstad, but were unable to find a second bird he had heard at a separate, nearby site. Another single male Kirtland’s warbler that was found and photographed (see below) the weekend before our visit at another site about 15 miles away was not present on the day of our banding operation.
As we head into June, more surveyors have completed searching their sites for Kirtland's warblers, yet only one new observation has been reported since last week. This report came from a birder, not a volunteer surveyor, who happened upon a male at a Marinette County site where no Kirtland’s warblers had previously been recorded. This report now brings the total number of observations outside of Adams County to 5, with 3 in Marinette, 1 in Bayfield, and 1 (of a female) in Vilas County.
While our surveys began in May, the official Kirtland's Warbler Singing Male Census period doesn't start until Monday, June 6. Any unbanded males observed prior to June 6, must be relocated during the Census period (June 6-15) in order to be counted in the Census. Unfortunately, we have not been able to re-locate the Bayfield bird despite multiple attempts by volunteers and staff. We will continue to check this site and will also look for additional unbanded males in Marinette County. We must keep in mind, though, that bachelor birds tend to wander, which could have caused the same bird to be seen at different locations and times. We will follow up on the Vilas County female next week and will continue to look for birds at satellite sites in Adams County. Stay tuned for new reports as we step up our efforts during the two-week Census.
USDA-Wildlife Services has had three cowbird traps in operation at the Adams county site since April 18. Wildlife Specialist Barry Benson reports that through June 3, a total of 143 cowbirds have been trapped so far this year. This compares to 201 captured through 7 weeks of trapping in 2010, and 272 for the same period in 2009. This marked decrease in captures is also being observed by the cowbird trapping program in Michigan, where captures to date are down more than 50% over the 10-year average. We plan to continue our cowbird trapping through mid-June.