Spring banding 2004 took place on 31 days from 15 April to 3 June. An average of 18 nets (12 meter equivalent1) were open an average of 5.4 hours per day. We lost five whole and eight partial days to bad weather. It was the rainiest May on record (8.46″ at Metro airport), but often our closures were due to wind. Mean starting wind speed was 7.6 MPH, not great for banding. One day we had to close when it started to snow quite hard. I think this is a first for a spring banding season.
We banded 639 new birds and had 113 recaptures of 64 species (includes Ruby-throated Hummingbird and House Sparrow, which are not banded). A total of 788 birds were netted (this includes birds released unbanded). Our capture rate was 31.3 birds per 100 net-hours. Here’s a quick comparison of this year versus previous spring means —
Due to the weather, it was a lackluster season. Not only did we miss time due to rain or wind, a stubborn frontal system floated north and south through the state or just south of the border. The early part of migration was good, but once the front appeared the entire latter half never really materialized in great numbers. While we expected to see an echo of last fall’s high numbers of spruce budworm specialists — Tennessee, Cape May, Blackpoll, and Bay-breasted Warblers — but they are later migrants and largely snuck by us due to the front.
Probably due to flooded conditions in the banding lanes, numbers of some ground-foraging species were down on a pernet-hour basis: Song Sparrow -36.4%, White-throated Sparrow -12.5% (although present in huge numbers away from the banding site), and Swainson’s Thrush -11.2%. The same conditions probably contributed to a boost in a couple of species that like wet conditions: Common Yellowthroat +44.4% (after a large increase last fall) and Swamp Sparrow +56.8%. Magnolia Warblers were up modestly (27.7%). The biggest gainer was Lincoln’s Sparrow. With 33 banded versus a 12-year spring mean of 12.9, they were up 108.1% per 100 net-hours. These were the most interesting trends for species with decent sample sizes.
Hooded Warblers are annual here, but always a treat. A female banded on 16 May was only our second ever (photo above right). Black-billed Cuckoos are also a crowd-pleaser, such as the one we banded 27 May (photo right). We had the time to take detailed measurements of nearly all of our “Traill’s” Flycatchers this spring, and confirmed what our surveys indicate: that most of the birds that can be identified through measurements are Willow rather than Alder. Only one definite Alder was banded, but another sang in the banding area for about a week.
A total of 157 species were recorded in the city of Dearborn, most on campus, for the spring period (March – May). This is the highest number we’ve tallied in 10 years. The first Horned Grebes in over 10 years were found on 28 March in two locations off campus. An American Bittern on Fairlane Lake was our second in two years. White-eyed Vireos were found all over the region in good numbers this spring, and we recorded two as well. Certainly the highlight of the year was Dearborn’s first Varied Thrush on 16 April near Edsel Ford High School. This one-day wonder is a western species. Cerulean Warblers are a species of concern over most of their nesting range, so it was good to have five records here this spring, consisting of at least two birds. Two Prothonotary Warblers hung around the lake in late April, furnishing great looks for many people. A Worm-eating Warbler sang tantalizingly close to one of our nets, but turned out to be another “one that got away.” UM-Dearborn remains one of the most reliable places in southern Michigan for Clay-colored Sparrows. Two showed up on 9 May, and one remained until 12 May, singing on the edge of a campus parking lot! Misses include Cape May Warbler and, unfortunately, Connecticut Warbler, which is quite reliable for us here.
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- In order to compare different locations or years that may operate the same number of hours but with more or fewer nets, capture rate is calculated by “net-hours.” One net hour is one 12-meter net open one hour, or two 6-meter nets open one hour, etc. This rate is often expressed per 100 net-hours for more manageable numbers. ↩