The chart below shows the number of species seen on campus each day since 2 May (the yellow line) as well as the number of warblers species (the blue bars). Click to enlarge.
The best day of the season was 10 May, with 95 species recorded, 25 of which were warblers. For some perspective, there are 37 species of warblers that occur regularly in Michigan (4 more are considered accidental; we have recorded all but 2 of the 41 species in Dearborn in the last 40 years). Some of the warbler highlights were a Kentucky Warbler on 10 May, our first record since 2006 of this southern species, and a female Prothonotary Warbler, which was present from 9-11 May. A gorgeous Golden-winged Warbler was also seen from 10-12 May. Closely related Blue-winged Warblers have also been present, while on 8-9 May, a hybrid of the two, a "Brewster's" Warbler, was observed; it sang a Blue-winged song. The total number of warbler species for 2011 so far is 28.
Other bird highlights of this period include a Summer Tanager and an Osprey on 10 May; a fairly early Olive-sided Flycatcher on 12 May, and two Red-headed Woodpeckers on 13 May.
We have recorded 133 species on campus so far in 2011. The total for Dearborn for the year is 151. This includes two records of Clay-colored Sparrow. One was this bird, photographed by Cathy Carroll along the Rouge River near the TPC of Michigan on 10 May.
Another was singing at the fallow sunflower field at the south side of Hubbard at Southfield. That location also hosted up to 10 male Bobolinks from 6-8 May.
I have added a box to the RRBO Latest Sightings page that includes links to bar charts for all species recorded on campus and in Dearborn which have been entered into eBird. This includes 2011 only, as well as all records input so far back to 1994. I have mostly put in spring and winter data, but am now working on summer and fall data. This is already over 2000 individual checklists. I try to add new data daily, so check back regularly.
I think migration has been terrific due to a combination of things. First, we did not get the very early warm spells that we have had the last couple of years, so trees and shrubs did not leaf out early. This has made viewing conditions quite excellent. Cool mornings have concentrated birds in sunny spots in the morning, and also resulted in many insects being most abundant near the water's edge (on campus, along Fairlane Lake). Thus, birds have been easier to find. Some credit has to be given to the luck of weather patterns, which are always the wild card. Finally, I think we are recovering from population losses that were due to the dramatic cold spell in the eastern U.S. in spring 2007 (I discussed this on the RRBO web site the following spring).
There is a lull right now, but I expect we will get one more good wave of migrants before the end of the month. Viewing conditions will be more challenging now that foliage is thicker, but do your best to get out and enjoy!