Prime Time: A buck cowbird and his persistent 'rival'
In July 2000, I did a column about brown-headed cowbirds (Molothrus ater), our major obligate brood-parasite.
Other brood-parasite cowbirds occur in Latin America, two of them ranging into the Deep South and the dry Southwest, respectively. Aside from being brood parasites, cowbirds are ordinary New World blackbirds, family Icteridae. They feed on seeds and insects, plus ticks and other external parasites of bison and cattle.
This essay is about "my" 2011 male cowbird. I think it's always the same male, but he's not banded, so I'm not sure. This is the first summer he's shown up at our dining nook window.
Like many icterids, cowbird males are more strikingly marked than females. Cowbirds' mating arrangements vary. In an area with lots of nests to parasitize, cowbirds are often monogamous, each male trying to monopolize a female that he defends from other males. If potential host nests are sparse and females have to range over large areas to find them, mating may be more promiscuous. Cowbirds have no commandments to obey, or to pretend to obey.
Like other blackbirds, male cowbirds sing (not a pretty song) to attract females. But they also combine song with a "dance." Cowbirds' most closely related kin are red-winged blackbirds, which also combine a non-melodious song with a display. You can read more at: http://news.nationalgeographic.com/news/2004/01/0122_040122_cowbirdsongd.... For more info, enter "cowbirds" into a search engine. Most sites I found seemed reliable.
Two birdseed feeders are just outside the window: a plastic cylinder hanging from a hooked vertical iron rod, and a simple plastic tray with a plastic roof held to the window by suction cups. About 7:30 a.m. Monday June 13, as I stood in the kitchen, here was this male on the plastic roof of the window feeder. He showed no interest in the seeds below, but repeatedly turned one profile and then the other toward the window. I don't know how well he could see into the house. It was bright daylight out, and no kitchen lights were on. Then he faced the window, fluffed up his feathers, half-spread his wings, and bowed. He probably also "sang," but I couldn't hear through the glass. He displayed at least three times, a minute or so apart, but flew off when I had to walk past the dining table.
That was the standard male cowbird courtship dance, and I suspect it was directed toward that "other cowbird" that was mimicking all his movement just inside the window. And that cowbird was not a female to court, but a male, a potential competitor. So the male cowbird "dance" serves both as courtship display and male-competition display: "My fluffed out feathers and exaggerated bow make me look just as big as you, and probably more adept at dancing. So there."
We need to remind ourselves that individual animals don't have the kind of self-image we do. I don't deny that they are truly conscious or self-aware (some biologists and psychologists emphatically deny both). But, at some stage in childhood we come to understand mirrors. Even without them, humans easily build explicit understanding that the features we can easily see in ourselves (arms, feet, navels) and some we cannot see but can feel (external ears, bald spots, beards) correspond to features we see in others. So we conclude that we are pretty much like other members of our species. Animals mostly have little trouble telling their own species from others, but "my" cowbird has no basis for realizing that the cowbird on the other side of the transparent barrier is mimicking him exactly. It's more "When I do this, he does that."
I have no schedule for bird-watching from that window, so I don't know how regularly he shows up to do this, or when he first started. Thursday, June 23, after many rainy days, I watched the same (?) male from noon-12:20 p.m. and took pains not to scare him off. Over some 20 minutes, he displayed to his reflection at least a dozen times, and then, not abruptly, turned and flew off. I imagined him thinking, "My, that fellow is persistent, but I showed him." He came back at 1:15 p.m., but I was moving and he flushed.
Saturday, June 25, I was lunching on the patio when a male cowbird lit briefly on a nearby spruce. He had caught a cabbage butterfly, obviously not intended for a nestling.
"My" male's behavior cannot be adaptive. He's not impressing a female, and not driving away any real competitors. Perhaps his display is somehow defective, so the girls won't give him a tumble, but a guy has to do what his hormones tell him. I hope he gets some solace from his success at impressing that capable rival on the other side of the transparent barrier.
Evan Hazard, a retired Bemidji State University biology professor, also writes "Northland Stargazing" the fourth Friday of each month.