Playback Experiment, 2013 Edition

In my last post, I talked about the usefulness of our robotic grouse for studying complex social interactions on the lek. This week we tried another method for modifying a male’s social experience– audio playback.

Male Sage-Grouse listening to our rock speakers.

We have a long history of playing back sounds to the Sage-Grouse. For the first several years our basic behavior studies were running along side the ‘Noise Project’, an extensive research program into the effects of noise associated with energy development on the grouse. The centerpiece of the Noise Project was playing back the sounds of two common noise sources (drilling sounds and road noise) from the Pinedale Anticline/Upper Green River area.  We used fake rock speakers, possibly the same kinds you might have seen in a SkyMall catalog, to play these sounds at leks, and compare how many birds showed up and their behavior between the noisy leks and control leks that had. I’ll talk more about the results from this project in a future post.

We also used the speakers in 2011, this time as part of the basic behavioral research program. We’ve been interested in the importance of “courtship skills” in the males, and part of that is how attuned males are to changes in their social environment. Does a male change his courtship behavior a lot when a female gets closer, or not very much? Our first experiment with the fembot showed this was related to the success a male has in courting females.

One species used in our 2011 playback study: Pronghorn

Our experiment in 2011 was designed to look at another dimension of responsiveness- how attuned are males to the threat of potential predators? Here we chose alarm calls o f three different species that live with the sage-grouse: ravens, killdeer, and pronghorn antelope. We played these from the rock speakers and measured the strength of the grouses’ reaction, as well as how long it took them to resume their original behavior. Analysis is ongoing, so we don’t yet know how this sort of “ecological” responsiveness relates to their social responsiveness or their success on the lek.

Fast forward to 2013, and we’ve set up the speakers once again, this time to measure how males respond to other males. It would be great to have a robotic male, but as you can imagine, making a mechanical male that is realistic enough to give a convincing display would be a steep technical challenge (never mind making one sturdy enough to withstand an attacking male). Instead, we are playing back the sounds of male struts from the rock speakers to see how males respond to a simulated male at the edge of the lek.  Anna has been putting together recordings with different call rates, so we can see if they are attuned to differences in the signals that males may be sending out. We’ve only just begun, but this will hopefully allow us to collect some interesting data on how males respond to other males while Gail puts together the new fleet of robots.

We also played a control vocalization– Horned Lark.

In other news, we observed the first copulation of the season yesterday! The breeding season has officially begun. Our earliest observation ever was on March 19th (in two different years), so we are on the early end of things.

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