ALWAYS IN SEASON/ MIKE JACOBS: Dance of the sharp-tailed grouse seems purposeful chaos
At this time of year, nature puts on such an extravagant show that it's hard not to be prurient. A case in point is the courtship dance of the sharp-tailed grouse. This is going on with exceptional intensity this year, because the grouse were late getting about the business, due to the late spring. There was little activity at the local lek until mid-April, and that was rather subdued. With the onset of strong sun and warm weather, the mating rituals of this iconic grassland species took on real intensity.
A lek is a dancing ground. The grouse gather there to display. Usually referred to as dancing, this activity includes jumps, dashes, pirouettes, feints and sometimes fights, and a variety of more or less threatening postures including extended wings, raised tails and crests. Plus there's noise, produced by stomping, scraping feathers together, forcing air out of special sacs on the sides of the neck and chattering at volume.
The point of all this is dominance, and the point of dominance is seduction. Close study of sharp-tailed grouse suggests that a single dominant male mates with as many as half the females that come to the lek, and two or three more are successful with the rest. This probably strengthens the species overall, since the strongest, most agile males are most likely to achieve dominance. Among grouse, this doesn't mean the largest males, however; in fact, smaller males have greater mating success.
Most grouse leks have a dozen to 20 dancing males, my research has told me. Last week, at least two dozen were performing on the local lek, which is near our place west of Gilby, N.D. This is the largest number I've seen there in nearly two decades of watching. The birds seem to have at least two separate dancing circles, and perhaps the beginnings of a third, and birds seem to move from one to another, leaving a nucleus of four to six birds in the tightest circle. That's likely where the action occurs. A wildlife biologist friend of mine suggests the other circle may be the nucleus of a new lek. Perhaps this is the way that younger, less sophisticated, less agile and less dominant birds get their chance, eventually, to contribute to the grouse gene pool.
The population of grouse seems to be growing in the area, which struck me as counterintuitive, since there's been no increase in habitat, and other grassland birds seem to be decreasing, including such species as meadowlarks and common snipe. The explanation is quite simple, though. From the perspective of a sharp-tailed grouse, the winter probably was a fairly comfortable one. While we humans grumbled about the length of the winter and the relentless cold and wind, the grouse were warm in their winter plumage and they had access to plenty of food, since snow cover was slight in our area. This probably allowed a greater percentage of last year's hatchlings to survive and to join the lek this spring. Of course, that would also mean a smaller percentage of experienced males on the dancing grounds, and that could account for some of the crowding and chaos I saw every time I went to check on the birds.
Grouse on a lek behave in some ways as if they are a single organism. The dance can stop as if on cue. I've puzzled about what might be involved, whether the birds sense something unusual or potentially threatening, and communicate in some way. Perhaps a passing hawk? Perhaps a flock of noisy geese? Perhaps a movement or a beam of light from the car where I'm hidden (or so I imagine)? Equally puzzling, again as if on cue; the dance begins anew, and every bird takes it up at the same moment.
Although most of the two dozen dancing birds were strutting on the lek, one settled on the gravel road in front of my car, and put on his show, apparently just for me. It seems ludicrous to think that he could imagine dominating a machine, even a small one. Perhaps he was a sentinel posted to evaluate my intentions and signaling them to his fellows on the lek. That's not as outlandish as it initially sounds. I found numerous references to solitary dancers strutting near blinds that biologists had set up to watch grouse.
The whole thing reminded me of an epiphany a student on one of my field trips experienced while we were watching mule deer in the Badlands. Entranced by the apparent unity of the herd and their tendency to act together, relaxing or taking flight, he suddenly whispered, "It's like one animal."
Yes, I thought, and that's how I felt about the directed chaos I saw on the local lek last week. All this frantic activity, the simultaneous fits and starts, the purposefulness of the display, is directed at one goal only: survival as a strong, tightly knit, unified and thriving part of nature.