Metro Beach Metropark
Bird Banding

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Summer weather conditions extended entirely through August and well into September this year, with hot days all through August (a few days exceeding 90-degrees). Temperatures soared into the 80s on occasion in September, and even to 86 on October 6. This was followed by a distinct cooling through the rest of October with highs in the 40s to 60s and lows into the 30s. High winds forced early closure on several days, and one day was rained out completely. Vegetation in the banding area had grown up considerably from the spring, but due to a very dry summer there was no standing water.

Banding was conducted on a total of 22 days between August 7 and October 28 (7 days in August, 7 days in September, and 8 days in October). As with the spring, the daily standard was to have 7.5 nets open for a minimum of 6 hours (longer if conditions merit), beginning as soon as possible after entering the park at 6:00 a.m. and setting up all the nets. In mid-season, another net (9-meter) was added, bringing the total number of nets to 8.25. The total coverage of 148.50 hours, and 1066.00 net hours, was slightly below the minimum daily standard.

A total of 868 birds of 59 species were banded, with a peak day of 146 of 21 species on 9 October. Also, there were 99 recaptures, and 26 birds were released unbanded. This fall, the overall capture rate was 93.4 birds per 100 Net Hours.

Specific comparisons with Ellie Cox’s 1989-1999 study is made in the following table (Table 1), with the caveat that not all data from these seasons has been thoroughly reviewed or entered into computerized format. Some of the differences are real, while others can be accounted for by our earlier start and later finish this year. Ellie opened her station from 15 August – 9 September (mainly after 21 August), and closed from 7-22 October (mainly before 10 October).

Highlights included a first ever Orchard Oriole and a first for fall Eastern Towhee. The Yellow-breasted Chat was a personal first, and only the second for the fall season. A Sharp-shinned Hawk was only the third ever at this station.

Record numbers were banded of several species, including Ruby-throated Hummingbird (only banded starting in 2004), Carolina Wren (tied), House Wren, Winter Wren, Gray-cheeked Thrush, Hermit Thrush, American Robin, Orange-crowned Warbler (tied), Canada Warbler, Northern Cardinal, Fox Sparrow, and White-throated Sparrow. The record number of American Robins was largely due to opening the station earlier as the record had already been broken by August 21, and the White-throated Sparrow and Fox Sparrow records were likely due to staying open later. The other records appear to be "real" (i.e., unrelated to increased effort).

Numbers of most flycatchers, vireos, and warblers were low to very low. A few regular species were missed entirely, including Yellow-bellied Flycatcher, Least Flycatcher, Philadelphia Vireo, Veery, Yellow-rumped Warbler, House Finch, and American Goldfinch.

*Ruby-throated Hummingbirds were not banded between 1989-1999

Released Unbanded

American Woodcock 1 (First ever, but got away!)
Black-capped Chickadee 1
House Wren 1
Golden-crowned Kinglet 2
Ruby-crowned Kinglet 4
Hermit Thrush 3
Common Yellowthroat 1
Northern Cardinal 1
Swamp Sparrow 1
White-throated Sparrow 10
Baltimore Oriole 1

Recaptures are a good indication of how migrant birds use the area as a stopover site. This fall, there was a total of 99 recaptures, which included one bird originally banded by Cox, and 6 birds originally banded in spring 2005, which were surely breeding birds.

The excellent recapture rate (11%) this fall provides strong evidence for the importance of this area at Metro Beach for migrant birds as a stopover site, and an important area for breeding birds as well. Table 2 shows all same-season recaptures for Neotropical migrants, shorter distant migrants, and year-round residents, and showing number of days between recaptures, and weight gain or loss.

RECAPTURES

Recaptures from Spring 2005

Song Sparrow (AHY-U), 1961-11610, was banded on 09 April 2005 as AHY-M and was recaptured on 20 August 2005 [133 days]

Song Sparrow (AHY-F), 1961-11671, was banded on 14 May 2005 as AHY-F and was recaptured on 21 August 2005 in breeding condition [99 days]

Song Sparrow (AHY-M), 1961-11683, was banded on 25 May 2005 as AHY-M and was recaptured on 16 October 2005 [144 days]

Northern Cardinal (AHY-M), 8101-31394, was banded on 09 April 2005 as AHY-M and was recaptured on 13 August 2005 in breeding condition [126 days]

Northern Cardinal (AHY-F), 8101-31391, was banded on 03 April 2005 as AHY-F and was recaptured on 03 September 2005 [153 days]

American Goldfinch (AHY-F), 1671-11425, was banded on 07 May 2005 as AHY-F and was recaptured on 14 August 2005 in breeding condition [99 days]

Northern Cardinal (AHY-F), 1631-01355, was banded on 05 May 2001 as AHY-F by Ellie T. Cox, and was recaptured on 13 August 2005 in breeding condition [1561 days]
Age: at least 6^th year.

Some interesting trends can be detected from this recapture data. For example, the banding site allowed some Neotropical migrants, such as the Gray-cheeked Thrush and Ovenbird, to gain considerable weight before continuing their migrations. One Ovenbird in particular was the overall season champ for weight gain, with a whopping 35.7% increase over a 22-day stay.

Resident Northern Cardinals seem to show weight losses and gains somewhat randomly, but the weight losses can be well correlated with periods when these birds were undergoing heavy body and flight feather molt.

The shorter distance migrants, especially Hermit Thrush and White-throated Sparrow, show mixed results. Some recent evidence from other migration stations show that the digestive systems of these migrants atrophy during long flights, and when the birds arrive at a stopover site, it may take a day or two for their digestive systems to become fully functional again. In the meantime, the birds do not feed much, and will actually lose weight. This appears to be well shown by the large number of recaptures after one day of both these species, most of which do show some weight loss. Also note that in most cases where recaptures are entered for several days, there is modest to significant weight gain. One notable exception is a White-throated Sparrow which arrived without any fat, and was recaptured three times over a period of 8-days, showing a weight loss each time. This bird lost a total of 25% of its body weight (the equivalent of a healthy kinglet!), and in fact was found dead in the net, having apparently been hit by a hawk before falling into the net. This rather graphically shows that weaker birds are easy victims for raptors, probably the Cooper’s Hawks, which unlike in spring were hunting occasionally in the banding area. But, there was no evidence that the hawks ever attacked birds that were caught in the net.

The gaps in the table where weights were not taken, either when the birds were banded or when they were recaptured, reflects busy days where some data collection had to be sacrificed in order to process all the birds. Additional help on these days might have allowed this data to be collected.

Moore and Aborn (2000) note:

"A migrant arriving at a stopover site in a fat-depleted condition is faced with the dilemma of needing to find quickly suitable habitat where it can deposit fat, while possibly not having the energy stores to adequately search among habitats. If high quality habitats are few in number or widely dispersed, fat-depleted migrants may be compelled to settle in a lower quality habitat, resulting in a longer stopover and delayed arrival on the breeding or wintering quarters."

A good number of migrants was banded at this locale, along with a high number of recaptures (11%) of bird stopping over for 1-22 days. During these stopovers, weight gains (and losses) of many migrants was documented. While weight gains are clear testimony to a site’s quality of resources, weight loss should not necessarily be interpreted as a sign of lower quality. A recent paper, which has unfortunately escaped into my extensive periodical collection filed in my basement (so I can’t cite the reference), shows that a number of nocturnal migrants will actually have atrophied digestive systems, which reduces the weight of these organs which are unnecessary for extended non-stop flights. On arrival at a stopover site, the researchers discovered that it takes a day or two for the digestive systems of these birds to regain normal function, and thus weight losses were recorded for many individuals (all thought th have been new arrivals when first captured) after one or two days of stopover. This year’s stopover data for both Hermit Thrushes and White-throated Sparrows seem to strongly support the conclusions of this research.

These banding results continue to underscore how critically important this relatively isolated patch of habitat at Metro Beach Metropark is to migrating (and some breeding) birds.

I wish to thank the Metro Beach management, in particular Jim Pershing, for permitting this banding to be conducted on this property, and to thank the Nature Center Staff, particularly Leslie Sutton and Julie Champion. Thanks also to those able assistants who helped clear net lanes, and helped in many other ways through the season, including Russ Brown, John Bieganowski, Terri Chapdelaine, Joanna Cohen, Keely Dinse, Barbara Fiddes, Fred Kaluza, Linda Kaluza, Dave Lancaster, Mark O’Keefe, Carl Pascoe, Jim Pappas, Melissa Pappas, Neile Rissmiller, Ken Willard, and Sue Wright. I would again like to thank Ellie Cox for encouraging me to continue the project she established in 1989. And, a special thanks to both Macomb Audubon Society and Oakland Audubon Society for providing funds to replace worn out nets.

Moore, F.R. and D.A. Aborn. 2000. Mechanisms of En Route Habitat Selection: How do Migrants Make Habitat Decisions During Stopover? In Stopover Ecology of Nearctic-Neotropical Landbird Migrants: Habitat Relations and Conservation Implications. F.R. Moore, editor. Studies in Avian Biology No. 20. Cooper Ornithological Society.

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