Friday, November 14, 2003
When and where seen: Several large flocks of grackles have been seen in Carlisle in the last two or three weeks. Tricia Lamb reported a huge flock on Indian Hill on November 4; I saw a moderate-sized flock on November 5 opposite Daisy's Market, and another on School Street on November 9. Ken Harte has noted rusty blackbirds and red-winged blackbirds among the grackles.
Description: When close up, the grackle is easily recognized by its irridescent bronze wings and body, and a glossy blue head. It has a black bill and pale yellow eyes. From a distance it just looks black and one of the common names for the grackle is "crow blackbird." The tail is relatively long and keel-shaped. Overall, the bird is about 12 inches from tip of beak to tip of tail — the same length as a blue jay.
Distinguishing behavior: This time of year you are most likely to notice grackles in large noisy flocks. There may be several hundred in a flock which can descend en masse into an area blanketing the ground and the trees. The black bobbing mass of birds and the loud twittering and chattering is alarming to some household pets (grackles raise their hackles) and to Hitchcock-influenced humans. These large chat groups fly off when disturbed. In the A.C. Bent book, Life Histories of North American Birds, there is an account from 1832 of a meeting with "one of these prodigious armies of grackles. They rose from the surrounding fields with a noise like thunder."
Look-alikes: You can distinguish grackles from crows and blackbirds fairly easily by size. The crow is a much larger bird, about 17.5 inches from tip-of-beak to tip-of-tail, and not glossy — and the rusty and red-winged blackbirds are much smaller, about eight to nine inches long. Starlings often feed and roost in very large flocks, and have irridescent plumage, but they are about the same size as a rusty or red-winged blackbird, and have a yellow bill. The brown-headed cowbird is colored like a grackle in reverse — the head is brown and the body has a dark greenish-black sheen. If it switched heads with the grackle, you would have one bird all browny-bronze and the other all blue-green metallic.
Food: Grackles are essentially ground feeders, taking mainly insects including cutworms and Japanese beetle grubs, but also grain, seeds, corn and acorns. They can do damage to corn crops by uprooting seedlings, looking for cutworms, and again in the summer by taking young kernels. They are also known to eat bird eggs and even birds.
References: David Allen Sibley, The Sibley Guide to Birds and The Sibley Guide to Bird Life and Behavior; Cornell Lab of Ornithology at http://birds.cornell.edu/BOW/COMGRA/; National Geographic Field Guide to the Birds of North America; Arthur Cleveland Bent, Life Histories of North American Birds, a 21-volume series compiled from 1919 to1968, many chapters are available as an electronic book — findable with Google.
Those brownish bugs, not quite an inch long, that are coming into houses looking for winter shelter might be Western Conifer Seed Bugs. Harmless. Check them out in the Mosquito online archive - pick January 25, 2002, then select features and scroll to the Biodiversity Corner.
Last week the Biodiversity Corner was two years old. We have covered 74 species — 17 birds, 12 plants, 11 fungi, 9 mammals, 9 insects, 8 amphibians, 3 trees, 2 snakes, 2 lichens, and 1 arachnid. Thank you for your photos, ideas, sightings and columns and please keep them coming. Send to firstname.lastname@example.org or Kay Fairweather, 392 School Street, Carlisle, MA 01741.
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