Tag Archives: field season

In the home stretch

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A male in the snow at Cottontail Lek.

I’m sitting at my desk, once again watching snow swirl outside the window and listening to the quiet churring of the electric heater. We’ve been getting about one snow storm per week- this is at least the fourth that we’ve had since late March. With the possible exception of Jessica Blickley’s 2009 season out here, we’ve never had this much winter weather, especially this late into the season. It’s often getting legitimately warm by this time in April (daytime highs in the 70’s), but not this year!

With less than two weeks left with the crew, the last few days look to be even more critical than usual. We’ve got a lot of the normal wrap-up still to do- calibrating the array and acoustic localization system, taking down the array, and proofing all of the field data would probably be enough to keep us busy. Add to that some new things for this year including the sagebrush sampling I alluded to in this earlier post, two photo analysis projects, plus all of the video analysis the crew has been doing to identify males on the lek tapes- now our schedule looks positively packed.

Gail snaps a photo of me learning to drive the robot.

Unfortunately this list still leaves off two of our main goals for the season– running our experiments with the robotic female Sage-Grouse, and testing out the encounternet telemetry tags. The robots are finally done, or at least very close to completed, and we are hoping the tags might be shipped to us this week. Once the snow melts, we’ll need to hit the ground running almost literally to practice for the experiments, catch a couple of males, and get all of the other things done. A big storm now could scuttle all of these plans, but thankfully this one seems to be fairly mild, and we may only end up with an inch or two that should hopefully melt quickly once the temperature climbs back above freezing.

The season has definitely been a challenge, and not just because of the weather (although the alternation between snow and mud, with few dry days in the cycle, have been frustrating for us). I mentioned in the mid-season update about the lower numbers of males we’ve had on the leks this year. This has been more than just an issue about monitoring enough birds to allow us to conduct statistical analyses.

Monument Lek, our long-term study lek, reached the point where males were abandoning their territories. We normally collect data on the whole lek at once, with video cameras filming all the males, and our field technicians adding notes of field locations so we can figure out which male is where on the video screen. We also place microphones in locations across the lek in order to record all the males simultaneously. Neither of these methods works very well when the males pull up stakes and display from different areas every day!

We have had to be flexible this year and change our strategy on Monument Lek. Rather than a “record everything” approach, we have shifted to a focal male approach, where every morning we’ve tried to target a few of the males displaying around the lek for video and audio recording. We’ve managed, for at least two or three days, to measure strut rates and get sounds from most of the “regulars” that stuck around the lek for the last half of the season. We also have some mating success data for these males. Although it isn’t ideal, we will have at least some continuity with our previous data for this lek.

My last view of a grouse on Monument Lek this year may be one of these guys displaying in the sage far from the main clearing.

It’s hard to know what caused such a dramatic change on this lek, but I do have one (very speculative) hypothesis: lack of water. The main lek area features a prone tractor tire that is used as a water trough for the summer cattle. In most years, there is a puddle surrounding this tire, and sage-grouse of both sexes would visit this. Most females visiting the lek would walk from the northern corner down to the tire for a drink, and many of the top guys’ territories would either be near the tire or along this path of movement.

This explanation would fall under the hotspot hypothesis for lek evolution. This is one of several hypotheses put forward for why males would cluster together on a lek rather than pursuing other mating strategies such as, for example, remaining with one or more females (like most birds). The idea is that males are able to assess where the density of females is likely to be highest and several males will settle there. If there is a resource drawing the females in, they aren’t defending the resource itself, but instead are taking advantage of an area of increased female traffic.

There Will Be Mud

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Wyoming weather is still keeping us on our toes. After bouncing from lows around 10 to warm nights in the 40’s and 50’s at the end of March, we thought we might be back on track for another warm year like last year. Not so fast! A small winter storm became a big one, and we ended up with more than a foot of snow earlier this week. I’m not sure we’ve kept records, but this was probably the second or third biggest snowfall I’ve seen since I’ve been out here.

The biggest was in 2007, I think a day or two after the Pangolin Pictures/PBS crew wrapped up filming, when we got closer to 3 feet of snow. That hit right in the peak of breeding, and we were shut out of Monument Lek for at least 3 days. For our 2013 storm, the peak in breeding had pretty well wound down, so a day or two absent from the lek didn’t feel like the end of the world for us. It did lead to one of those stunningly beautiful mornings we get out here. I think a snowy dawn is a close second to a Wind River moonset as my favorite events out here.

The storm started on Monday, and on Tuesday, we headed into town early due to frozen pipes. The same weather forecast that underestimated our snow by about 80% also failed to inform us that it was going to be single digits at night. Ah, the joys of trailer living. Tuesday and Wednesday were snow days. It took a lot of shoveling by the crew just to get the vehicles out, not to mention clearing a path for the ATVs to get out (and Huff Sanitation to get in). Thursday we finally got out to two of our three study leks. Kate headed out on snowshoes to get a count of birds on Monument Lek, while Christa, Elena, and Max tackled Chugwater Lek, with Elena and Christa trying to get close up video of female behavior for Anna’s projects.

Chugwater Lek proved to be an exciting place. There were at least nine matings, suggesting that the weather had caused some nest failures, and some of the females were looking to re-mate and try to nest again (or alternatively, the snow kept the females away, causing a build-up of receptive females that we happened to catch on our first day back). Second, the guy doing almost all of the matings turned out to be the guy we captured and banded the morning before the snowstorm. Male number 335 (also called ‘Mufasa’), with green and white bands, left our care in very good shape- all his tail feathers, etc. When Elena didn’t see his distinctive tail feather pattern (‘buttprint’) on the morning after capture, we were hopeful that we had gotten the top guy on the lek. In previous years we’ve done a lot of our capture at the end of the season when males were about to pack it in for the year anyway, and often haven’t seen them come back to the lek until the next year. It’s nice to see a released bird not only return, but obviously still be top dog even after a day or two away from the game.

By Friday the crew was back at all three leks. Unfortunately there’s another storm on the horizon for Monday. It’s only supposed to dump 3 inches or so, but that’s pretty much what they said last time. In the mean time, all that snow is melting, and we’re going to be dealing with some of the worst mud we’ve seen all season. Keep your fingers crossed!

<Note- I’ll throw a few more photos up next time I’m in town- the photo uploader hasn’t been working well this morning>

What’s on the menu?

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Monument Draw, between our camp and one of our leks. Sagebrush is definitely the dominant plant out here!

Our focus in our Sage-Grouse research has been fairly limited to the lek– this is still keeping us busy even after many years of study! However, it’s always nice to get a more comprehensive view of the ecology of whatever organism you are studying, and towards that end, we have initiated a collaboration with Dr. Jennifer Forbey from Boise State University. For the Sage-Grouse, their life revolves around the sage plants (genus Artemesia) that form most of their diet, especially in the fall and winter. Jen spent a few days with us a the end of March to see our site, tell us about her research on the interaction between sage and the animals that depend on it, and plan out the first steps in our research together.

What at first seems like a uniform world of “sage” out here turns out to be a variable landscape of food quality for the grouse. First of all there are different species of Artemesia. In our site we have at least two, the basin big sage and Wyoming big sage. These are usually pretty distinguishable, although sometimes smaller Basin plants can look like larger Wyoming plants. The leaves are usually pretty different though, as Jen demonstrated. Jen gave us a handy rule of thumb for this: you can remember the Wyoming sage is like a Wyoming native giving the middle finger to the Californians! We got a laugh out of that.

Sage-Grouse usually cut all but the base of the leaf.

Jen showed us how to distinguish foraging by different herbivores in the area. The grouse tend to pick just the leaves, so if you have a sharp eye you can find the remaining leaf base. Old foraging will show a brown scar in the middle of the leaf, but if you happen to find a place where they have been foraging during the past day or two it will be bright green. Rabbits, on the other hand, tend to cut the entire stem off in a neat angled cut. They harvest the leafy parts before the sage can mount an defense (see below).

Neat diagonal cut = rabbit

Sage stems harvested by rabbits.

The sage are full of all sorts of secondary chemicals such as phenols and terpenes, making them pretty unpalatable to most animals. Jen had us taste a leaf and those little things pack a punch, leaving a persistent bitter taste in our mouths.

The Sage-Grouse obviously have a way around this since they eat almost nothing but sage for months out of the year. One adaptation is a specialized gut with two large caeca (blind pouches coming off the intestine). These are places where bacteria can work their magic and help detoxify and digest the sage. On the lek you’ll often find a dark, gooey tar-like caecal casts left by the grouse, which look very different from their normal (goose-like) poop. I can’t believe I don’t have a photo at hand to show this!

It gets more interesting when you look at variation among plants of a species. While the Sage-Grouse can eat the sage, Jen’s work has shown they prefer to feed off of plants that have less of these secondary chemical compounds. Eating bad quality sage with too high a concentration of these means the grouse have to work harder at digesting for fewer nutrient rewards.

The sage plants themselves are not passive players in this. When something starts to damage the leaves of a sage plant, it will begin to produce more of these defensive chemicals. Even more impressive- as the volatile compounds reach the air, they can spread to nearby plants, causing neighboring bushes to ramp up their production of chemicals as well. What this means is that the longer Sage-Grouse spend foraging in a given patch of sage, the lower quality the food becomes.

Male sage-grouse leaves the lek

Male sage-grouse flying.

This chemical response by the sage may solve a mystery stemming from a 1980’s study of sage-grouse behavior from the Mono Basin in California. Sandy Vehrencamp and colleagues followed radio-tagged males and found that the “good” males (with high energy reserves) were actually traveling farther from the lek, while the males with poor reserves foraged close to the lek. It could be that the plants near the lek tend to build up more of these secondary compounds, so males that can travel farther may actually encounter better areas in which to feed. We hope to follow up on this possibility as we learn more about the way that off-lek foraging behavior interacts with on-lek courtship and performance.

Mid-season Update

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It’s March 31st, and as we trundle towards April, I realize how tardy I have been with general updates this year. Every season is a little different, and this one is throwing us some curves.

Nine Mile Hill shrouded in snow.

We saw our first copulation on our biggest lek, Cottontail Lek ten days ago (March 21st). This date is pretty normal. We’ve found one earlier (March 19th) in a couple of years, and later some other years. Usually once we see the first one, within a few days every lek is showing multiple copulations. Not this year! We got hit with a blast of really cold weather (lows around 10℉) as well as a few inches of snow.  The females seemed rethink their interest in the males, and it was several days later before we saw the next mating on any of the leks. So while the breeding season opened at a fairly average time, I think the season as a whole is going to be on the late side. On balance, I’m not sure if this will be good or bad for our work this year. The longer we have big groups of real females on the lek, the harder it will be to give our robotic females a private audience. On the other hand, the males may stay interested in courtship a little bit longer so we may not have the problem of the males just giving up at the end of the season the way they sometimes do. We’ll have to see what happens!

Two male sage-grouse battle in the fresh snow on Chugwater Lek.

Other challenges we’ve had to contend with are the incredible shrinking leks. Our initial impression from the first couple of weeks of the season seems to be correct– male attendance is down considerably from last year in our area. This may be due to the drought the Lander area is experiencing, at least there’s not an obvious other candidate for the decline. Our sage-grouse manager contacts have mentioned that the rough demographic analysis from hunting data suggested low recruitment (not many yearling birds taken compared to the number of adults).

To give you a sense of the change in abundance since we started the project here: Monument Lek, our main focal lek since 2006 when it had over 100 males, has dropped to under 10 birds and males are not staying as reliably on their territories. Anna has still gotten some playback experiments done, but Monument is right on the edge of being useful or not as one of our experimental leks.  We just showed the PBS Nature episode featuring our research (“What Females Want…”) as part of another outreach event down at the Lander Public Library. The footage was shot in 2007 when the male counts were an order of magnitude higher. The difference definitely makes us a little sad, and we are hoping this lek rebounds quickly as it has done in the past. Sue at the BLM told us that in the 80’s it was down to 4 birds, and later climbed back to over 100, so we hope this is another one of those cycles.

Shallow trenches prepared for laying microphone cables at Monument Lek. This lets us put microphones all over the lek, while keeping the cables underground. The speakers are for the playback experiment.

Otherwise we are in pretty good shape with most of our “normal” tasks. We have microphone arrays deployed on all three focal leks now, and have gotten several days of sound recording in.  We’ve also gotten at least one round of counts at our non-focal leks, to help the local sage-grouse managers monitor the grouse population in the district. The only things we are missing are the new robots (Gail is working on taxidermy aspects now, so those should be ready soon), and the encounternet telemetry tags. I say “only”, although those are definitely two very important pieces for our research goals this year and in the next couple of years!

Playback Experiment, 2013 Edition

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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.