Thursday, June 2, 2011

Common Grackle

Many birders hold Common Grackles in low esteem. Familiarity may breed some contempt.  Grackles are among the most abundant North American birds. They thrived with the clearing of eastern forests and moved west with the planting of shelter belts. Grackles are omnivorous, and their diet includes smaller birds; they are known to rob nests and eat hatchlings and eggs. Grackles can take over a summer bird feeder and the species causes extensive crop damage.

Common Grackle numbers can be phenomenal. Populations have been estimated at over a million birds in several eastern states.  Recently, however, grackle numbers have been declining--perhaps as a result of control measures. Decreases of as much as a third have been reported from Breeding Bird Surveys (Peer and Bollinger 1997).

When I discovered that this common species was not illustrated in my blog, Erika and I initiated a grackle search. We quickly discovered our bird on a piece of rusted farm machinery near Northfield. Even as I took these photographs, I was amazed by this displaying male's beauty. Previously, I did not appreciate the iridescence of a sunlit grackle. If you look carefully at the first photo, you may notice that its nictitating membrane is half closed. I was surprised to see that it is blue.
Common Grackles are not normally found west of the Rocky Mountains. An exception was a grackle that I banded in Aberdeen, South Dakota on 8 August 1994. On 10 August 2000, this bird was recovered in Vancouver, Washington. At the time, this record was only the seventh for Washington state.  Some confusion exists, however, since the finder of the bird does not remember reporting it.

In my book, Birds of South Dakota, I studied bird banding recoveries. I found that most South Dakota grackles winter in Arkansas (at least as evidenced by recovery records). Red-winged Blackbirds tend to winter further west, in Texas. Finally, most Yellow-headed Blackbirds winter in western Mexico.

1 comment:

  1. Not a fair description at all: the common grackle's population is in steep decline, and the bird is lovely by all measure, and the crop damage is negligible.