Fall banding 2001 took place on 47 days from 15 August to 4 November. It was a rainy, windy fall. For September and October combined, total rainfall was 6 inches above average! This resulted in us losing 16 whole and 9 partial days to rain, or brisk winds. An average of 20 nets (12 meter equivalent1) were open an average of 4.4 hours per day.
We banded 1763 new birds and had 451 recaptures. A total of 2424 birds were netted (this includes birds released unbanded). This broke our previous fall record, set last year, of 1526 new birds and 1961 birds netted, and represented the first season we broke the 2000-bird mark. Our capture rate was 58.3 birds per 100 net-hours. Previous fall means are 1117 new birds and 1410 total, and 54.4 per 100 net-hours.
Our best day was no doubt 15 October. We banded 202 new birds and 8 recaptures; 180 of the birds were Yellow-rumped Warblers. This eclipses our previous daily high total by nearly 100 birds!
Numbers and trends
This fall, 70 species (plus 3 not banded) were handled. Our record is 75 and we thought we might be able to hit it, but missed out on some species that aren’t usually too hard to get: Red-breasted Nuthatch (despite it being a good invasion year), Brown Thrasher, Brown-headed Cowbird, Red-winged Blackbird (although many dozens were lurking near our nets!), and Baltimore Oriole.
The breeding season was extremely hot and dry. We wondered what impact that would have on productivity, and thus the numbers of young birds coming through. Only a couple of species showed marked declines from previous fall means (total followed by previous fall mean, deviation from mean):
# American Redstart (11, 21.2, -48%)
# White-throated Sparrow (51, 91.2, – 43.4%)
The Black-capped Chickadee invasion that overwhelmed some banding stations in the northeast did not materialize here (we’re not complaining!). We banded 31 new chickadees, only 10 above the previous fall mean.
We did band some species in excellent numbers. Winter Wrens furnished the real fall story. The 9 we banded was 900% above the previous fall mean of 0.9; in the ten years of RRBO history, we’d only banded a total of 8 before this fall! They popped up (literally) in many of our fall surveys as well, so it was just a good year for these cute little birds. The 696% increase in House Finches (39 banded) was a mystery. While they are hitting the feeders at the new interpretive center, we did not capture them in nets anywhere near the feeding stations.
A few other species with increased numbers:
* Philadelphia Vireo (10, 3, +233.3%)
* Nashville Warbler (41, 17.7, +131.6%) +400%). This follows an increase of 400% this spring and 188% last fall.
* Common Yellowthroat (19, 5.8, +227.6%)
Thirty birds banded in previous years were recaptured this fall. Easily the most remarkable was a White-throated Sparrow (left) originally banded on 23 October 1998 which we recaptured on 4 November 2001! Migration stopover site fidelity is rarely documented, so this was an exciting recap! Runner up was a Red-eyed Vireo originally banded on 24 August 2000 that was recaptured precisely one year later, after a Peruvian winter vacation and Dearborn-area breeding season.
Our oldest recaptured Black-capped Chickadee was one originally banded as a juvenile on 15 August 1996. It has landed in our nets 16 times since then. Other slightly old birds were an American Goldfinch and a Northern Cardinal that were each originally banded in 1997.
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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. ↩