May 23, 2013
Written by Jack Sanders
Thursday, 12 May 2011 11:12
Brown-headed Cowbirds are “brood parasites,” laying their eggs in active nests of other bird species in the hope that the nest-builders will raise the cowbird young. In the process, the eggs or chicks of the nesting species are usually destroyed or starved as the bigger cowbird baby dominates the brood.
The cowbird was once only a Plains dweller, following the herds of buffalo and eating the insects they stirred up. Because herds were always moving, cowbirds moved, too, with no time to build a nest and sit on it. So they learned to use the services of other birds, laying their eggs — as many as 65 a season! — in the nests of other species.
Flo Vannoni of Redding witnessed the result.“For the past four years, phoebes have been nesting on the ledge above our kitchen door,” Flo writes. “There was a lot of activity back and forth this year again as they prepared the nest. And for about a week, one would be sitting on the nest with its mate bringing food.
“About a week ago this activity stopped — there would be only one bird coming to the deck near the house, but [it did] not go into the nest. Placing a ladder near to check the nest, I found four phoebe eggs and two white/brown-speckled eggs. Immediately I knew a cowbird had laid her eggs there. I recall seeing a cowbird sitting on the deck railing about the time the phoebe activity halted.
“I removed the cowbird eggs and left the Phoebe eggs. Being that the phoebes have not been sitting on the eggs for over a week, should I remove them with the possibility the phoebes will return to lay more eggs? What can I do in the future if I see this scenario repeat itself?
Flo adds, “One might think not being able to use the door for two months an inconvenience, but we look forward each year to hearing their call in the mornings and to seeing the babies fledge.”
I don’t know whether the phoebes would return to the nest if the eggs were removed, but Eastern Phoebes do usually raise two broods a season.
Some species have caught on to the cowbird trickery, and destroy the foreign egg. If a Yellow Warbler finds a cowbird egg in its nest, it may build a new nest atop the old — with the egg still in it. Yellow Warblers have been known to build as many as two nests atop an original nest, if the first two were parasitized by cowbirds.
On the Plains, some species have learned to recognize a cowbird egg and remove it from the nest.
“Guess who showed up at my birdbath this morning,” writes Debra Bender of Cos Cob on Tuesday, May 3. “A Blue-winged Warbler. Never saw one before.”
Suzanne Stuttman of Redding writes Friday, May 6, “Today was a pretty exciting birding day here in Redding. This morning, about 11 a.m., I saw two male Scarlet Tanagers at the forest edge. They were pretty high up in some old trees, which border the edge of the Tunxis Trail conservation land. About the same time, a Baltimore Oriole flew by. Later, at 2 p.m., our female hummingbirds arrived, as they do every year either on, over very close to, May 5th. Our males had already arrived on April 27.”
Jim Mullen had Rose-breasted Grosbeaks at his Ridgefield feeder last week.
Jen Weibel of Redding says on Thursday, May 5: “ Awake early, we looked up at a blue sky and there atop a tall oak, highlighted by the morning sun, sat a gorgeous male Scarlet Tanager. Thrilling! There is such a narrow window of time between their return to Connecticut and the trees being in full leaf when they are so difficult to spot.”
Bird Walk & Bird Breakfast with Audubon Greenwich, Walk: 6:30 to 8 a.m. / Bird Breakfast: 8 to 9:30 a.m.; Wood Thrush Conservation at Home & Abroad, with John Hannan from Audubon Connecticut, 9:30-10:30 a.m.; in Ketay-Asnes Barn, RSVP required for breakfast, $8 per person. RSVP to store: 203-869-5272 x221, greenwich.audubon.org
Bird Walk with Chris Bozak of Norwalk Hour and radio show “Bird Calls,” Saturday. May 14. at 7 a.m. (rain: May 21) starting at Wild Birds Unlimited, 356 Heights Road, Darien, 203-202-2669, darien.wbu.com.
Bird walk with Ed Kanze, author and columnist, Saturday, May 21, 7:30 a.m., meeting at the Trailside Museum, Ward Pound Ridge Reservation, Cross River, N.Y.
Early morning bird walks, various locations, Tuesdays, May 17, 24 and 31, Thursday, May 21, 7:30 to 9:30, Bedford Audubon, for details bedfordaudubon.org
Copyright 2011 by Jack Sanders. Send sightings or comments to: jackfsanders [at sign] yahoo.com, or to Bird Notes, Box 1019, Ridgefield, CT 06877; or call 203-438-1183, extension BIRD (2473), and leave a message with your report, spelling your first and last names and telling us your town. If you need help identifying a bird, try your local nature center. If you find an injured bird, call wildlife rehabilitator Darlene Wimbrow of Redding, 203-438-0618, Wildlife in Crisis of Weston, 203-544-9913, or Wild Wings of Greenwich, 203-637-9822. The columnist’s website is www. sandersbooks. com.
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