Underneath the calls of Vesper Sparrows and Western Meadowlarks the low blooping sounds of sage-grouse signal they are in the midst of their spring lekking displays.
A number of bird species, including sage-grouse exhibit this specific type of mating behavior where males come together during breeding season and display for females, with a dominant male at the center. The display itself differs across species, and for sage-grouse it involves the inflation and clapping together of air sacs.
In the car, on the way to a lek, state Wildlife Conservation Biologist for the northern region, Adam Brewerton, describes the displays.
“Sage-grouse have this kind of white collar around their neck of feathers," says Brewerton. "Most of the time when they're just walking around, you can still see that white but during the lekking, they'll really puff those feathers up."
"They'll fan their tail out, kind of like a turkey would. They'll pop up those chest feathers, those neck feathers, they'll kind of like set their wings a little bit, have these feather plumes off the top of their head, and then they have these air sacs in their breast. And they'll inflate those air sacs and do kind of this bloop sound and a bloop pop”
This particular sage-grouse lek is in a high elevation valley up blacksmith-fork canyon. Sagebrush shrubs provide some protection but the landscape is relatively exposed and these birds are large, almost the size of turkeys.
In order to avoid birds of prey and larger carnivorous mammals, males perform their lekking displays at dawn before the sun hits the valley.
They perform for females from March through May each spring, during which Brewerton and his collaborators survey the leks in order to make population estimates that are important for informing wildlife management.
These surveys have been occurring for many decades as the cyclical nature of sage-grouse populations have emphasized the importance of long-term population monitoring.
“As you're tracking, the populations you'll see, like a wave. So you'll see, like a population growing, it's increasing, as it kind of gets to its maximum, that growth slows down, and then it kind of peaks out and it starts to decline,” explains Brewerton.
Cyclical patterns in animal populations are relatively common and are largely related to resource availability in an ecosystem.
These populations fluctuate on about a 10 year cycle.
“Within our management plans, we'll have certain objectives and goals to kind of maintain populations at certain levels,” says Brewerton. “And it also just helps us, you know, make some of those decisions."
"We can be a little bit more liberal with some management actions, when populations are stronger, we'll be a little bit more conservative with them when they're a little bit lower.”
The agency also uses this data to determine the number of hunting permits given out for sage-grouse each year.
“The number of permits is directly proportional to what the population estimates are,” says Brewerton.
As Brewerton and I are chatting, all of a sudden nearly all males in the lek fly off, clear to the other side of the valley. The sun is peeking up over the mountains signaling an end to their displays for the day.
Because this population inhabits such a high elevation valley they are on a later schedule than others in the state and will spend just a few more weeks lekking before the reproductive season is over for the year.
