Eagle leaving Cottontail Lek at sunrise

Leks are predictable places to find groups of animals worried about fighting and mating and not always watching for danger. As a result, they can become targets for hungry predators looking for an easy meal. In some cases the large number of watchful eyes offers enough protection, and approaching predators are spotted early enough to give males and females a chance to flee. This is what we’ve normally seen with the sage-grouse- in most years golden eagle attacks (the main predator for adult birds on the leks) have been fairly rare in our area, and those attacks have almost never been successful.

I was fortunate enough to witness a couple of attacks last week. The first was an unsuccessful attack at Cottontail. This one was noteworthy mainly because it took place against a stunningly colorful sunrise. The urgent simultaneous take-off off the entire lek of birds alerted me to the attack, but I didn’t find the bird until it was already turned around and headed away from the lek.

Mel and Becca investigating the remains of the eagle kill at Chugwater

The next day I was at Chugwater, and just when I started recording and Becca and Melissa had overlook cameras running, another eagle flew in. This attack ended successfully (for the eagle at least), and it was able to catch a fleeing female grouse out of the air. It perched just out of sight behind some sage and ate the whole thing minus the wings, feathers and a few guts, within maybe a quarter of an hour. Some grouse had already returned to the lek, and were not terribly happy about an eagle all of a sudden appearing from just a few tens of meters away!

Prairie Falcon

On my next visit to Cottontail, we saw another attack, although I think this one was less serious for the grouse. A prairie falcon was diving at some males on the western end of the lek. The falcon was probably half the size of the grouse (especially an inflated grouse), and the harassed males mainly just fell forward on their face and vocal sacs to avoid trouble.

With the warm weather we’ve been having, the leks have been quite active over the past week. Male numbers have been fairly stable since the birds started showing up, but female numbers are quite high now, often exceeding the number of males. Leks really feel like different places when things get this busy- not only are the males much more active (displaying more and chasing off encroaching juveniles), but you also get a much different window into how females “shop”. The top guys are surrounded by females, and these females are constantly whining, pecking, and bumping each other to try to stay close to these top males.

Those females are there for a reason, and we started seeing matings on the leks on March 19 and 20^th. Within a few days, Cottontail and Chugwater had established some “high performance” males who managed to mate with 10 or more females in a single morning!

Melissa and Becca digging a shallow trench for a microphone cable.

On Sunday we had a break in our atypical windy mornings, and I was able to collect our first sound recordings of the season on Chugwater Lek. A long afternoon the day before by our crew helped get the microphones in place. We didn’t have any particular reason to limit the number of microphones this year, so we buried cables for 11 microphones this year instead of 8. The core area of birds is so dense that any improvement in accuracy of our acoustic location system might pay off in more calls assigned to individual males during analysis.

This cable has been part of at least 3 microphone arrays in the past. Oh the things it has heard!

The recording itself went relatively smoothly. I relabeled the cables in the blind so it would be as easy as possible to place the cables in the correct channel in the preamps. Staring at the end of the cable and seeing the many numbers this cable had already received made me feel a bit like an archeologist. There’s the worn and faded numbers from it’s original installation, the pink duct tape from the Blickley era, and other numbers indicative of other arrays on other leks that this cable had been a part of. It’s not always a given that things will be labeled on both ends, and I was left with two cables that I thought I knew where they went but wasn’t entirely sure. At the end of the morning I did a quick test by continuing to record while I picked up the microphones in order, just to make sure we knew which mic was actually connected to each channel. Good thing, as those two were mixed up! It’s always a good idea to double-check anything you do early in the morning.

Anna getting video of female behaviors on Cottontail

The unusually warm weather (lows of only 30′s or even 40′s!) and lack of snow seems to be pointing to a really early start of the breeding season. My morning at Cottontail seems to agree with this guess. Anna and I were on the lek (me to round out the roster of “buttprint” tail feather photos, and Anna to get video of female behavior. The lower part of Cottontail had 21 females, and they were not just there to forage. They were clustered pretty tightly together, and were hanging out close to the males. The last female left at almost 10. Nice to see so much activity, but it definitely reminds me that the clock is ticking to have everything in place.

It’s always important to go into a field season with a great plan, but sometimes it’s just as important to be able to adapt that plan to the realities of an unpredictable world. We experienced this quite a bit last year- first when the snow levels and late-arriving birds caused us to add Preacher lek to the two we were expecting to monitor, and second, when our initial tries at measuring “environmental responsiveness” in male sage-grouse failed completely (these are not the most curious birds), and we moved to a sound playback that seems to have worked quite well.

This year the big shake-up so far once again has been a change in leks. We wanted to work on Preacher, Monument, and Chugwater again, but our early season counts at Preacher have tallied only 2 or 3 birds! Not really enough to do much with. We aren’t sure where these birds have gone- whether this is some lingering effect of the noise introduction experiment from a few years ago, due to the prominent traffic noise drifting up from Rt. 789 near Riverton, or some other reason birds might be moving over to nearby Guston or maybe another undiscovered lek in the area. Either way, after considering our options, we’ve replaced Preacher with another lek in the area- Cottontail. Cottontail Lek is one of the closer leks- it is probably closer to camp than Chugwater. Like Monument, it is oriented in a valley opening out towards the Wind River Range. We’ve never done any experiments on either project there because it is just too big- even now counts are over 60 males, and back in the “big years” of 2006-2007, male counts could exceed 200!  We will be working on one end of the lek, one of at least two activity centers there.