Author Archives: alan_k

Why a Robot?

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Photo Gail Patricelli.

Yesterday we got to take off our researcher hats and put on our outreach hats (we also traded our field clothes for some clean pants). Gail and I brought “Snooki”, the latest version of our robotic female grouse, down to Lander to participate in Teen Tech Week at the public library. Word had spread among the library staff; they were quite excited to get to meet the robot in person. Some of the kids were apprehensive, but most jumped right in to give the test drive. I had loaded some videos of the fembot and the grouse on my iPad so they could see how she looked in action.

 

With the exception of the wheels, the robot makes a pretty convincing sage-grouse. This version has the mechanics tucked inside a fiberglass shell that was poured over a grouse-specific taxidermy mold. Gail artfully arranged real grouse skins over this to complete the disguise. “Snooki” can turn in place using the wheels, the body can pivot down, the neck bend up and down, and the head can swivel back and forth. You can see a video of the fembot in action at the bottom of this post.

Fembot (left) and "undressed" fembot, right.

One of the common questions we get at this sort of event is “Is the robot just for fun? What do you do with it?” Let me take a moment to answer that.

Our robotic sage-grouse

In my recent post, I talked about how we use leks as a way to study sexual selection and mate choice. Most studies of lekking animals have looked at male traits that don’t vary much over the course of the breeding season. For example, in peafowl, biologists can look at which males have the longest tails or most tail eye-spots, and see if that might relate to patterns of mate choice. You could picture this as each male holding up a sign with his “score”, and females look around until they find the male with the highest score.

Anyone who’s watched animal courtship knows that males and females aren’t always politely assessing each other from a distance. Real courtship often involves complex decisions and interactions: deciding whom to approach, how quickly, reading signals or cues and responding accordingly. For a male to succeed in the mating game, the skills required to navigate the complex world of courtship can be as important as the physical traits he carries. Some of you may even have personal experience with this situation– meeting someone who is very attractive but who comes on a little too strong, for example.

Unfortunately we don’t know much about the importance of these “social skills” in non-humans because they can be hard to measure, especially in the wild. This is where the robot comes in.  With a robotic female, we can control one side of the conversation. The fembot gives us two important tools for comparing males on the lek.

Male courting fembot.

First, it presents all males with a standardized stimulus. In live courtships, females may approach the top guys much more closely and provide signals of interest, while other males are consistently given the cold shoulder. The robot lets us measure all the males on an even playing field.

Second, it allows us to experimentally control the conditions of courtship. In a previous experiment, we could look at how male sage-grouse responded to a very basic aspect of female behavior– how close or far away she is from a male. With the more advanced version of the robot that we debuted last year, we could send either “coy” or “interested” signals to the males. I’ll describe the plan for this year’s experiments when we get a little closer to conducting them.

The older version of the robot ran on train tracks. Here we are moving her closer to two admirers.

The robot also serves an important function as a target of courtship- one of the skills we are interested in is the male’s ability to aim his best signal at the female, and in a past iteration, the robot could record what a female would hear, rather than what a biologist can record from some arbitrary position on the lek.

There are several ways that biologists can manipulate an animal’s social environment (video playbacks in the lab, audio playbacks of bird song, etc), but the robot gives us a unique way to interact with animals in wild.

What the tail end of a Sage-Grouse can tell you

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We’ve now been out in Wyoming for about two weeks as part of our Sage-Grouse research, and our great crew of technicians has survived their first week. We are still in the early-season set-up phase. Over the past few days we have been making good headway on a couple of important tasks.

Sunrise at Cottontail Lek. You can see several male Sage-Grouse displaying in the foreground.

The male sage-grouse seem to be getting in gear for their breeding season; we’ve seen them coming into all three of our research leks (Monument Lek, Chugwater Lek, and Cottontail Lek). This has allowed us to make sure the main display areas are in the same place as they were in past years. The same general lek site can be used over decades by many generations of grouse, but sometimes the exact area used by the birds may move a little.

Putting in stake B3

Once we have a good idea of where the birds will settle, we are ready to place our overlook observation blinds and also set up our grid of survey stakes on the lek surface. The stakes help us map out where males are displaying, in effect giving each male an address we can use to find him later on our video tapes of the morning’s activities. We’ve been doing this for several years and the males have never seemed wary of the stakes.

Actually setting up the grid of stakes is definitely a team effort, and always one of the first big jobs of the field season. We use long measuring tapes to try to get the spacing as accurately as possible. Typically one person holds the tape to check distance and alignment, and another person hammers in the stake. With two or three teams of two, this goes reasonably fast. We even had some nice weather on Monument Lek.

So how do we identify the males? We’ve banded a few (in fact, we’ve already resighted some males with color bands that were captured in 2011). However, most of our males are identified without ever laying a hand on them. When males display, they raise and fan their tail. This exposes their undertail coverts, each of which is tipped with white. Each male has a different arrangement of these (instead of a fingerprint, we call it his ‘buttprint’). The trick is to get a photograph of each male while he is facing away in display- we can then compare the photographs, and even take the photo into an image editing program to convert it to a simple black and white pattern.

These are some photos taken this morning on Cottontail Lek- see if you can tell these males apart.

Biologists use differences in appearance to identify all sorts of animals, from whales to tigers to wasps. Hannah, one of our field techs on the project, has introduced us to some software that has been used to help sort out individual photos of various mammal species. She’s been using it on some large African animals. We’ll see how it works with feather patterns.

With stakes and ‘buttprints’ we know who a male is and can describe where he is. These are both requirements for our research questions involving how males interact with other males and how they court females.

Arrival in Wyoming

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Although we are based out of the University of California Davis, our field studies of Sage-Grouse take us to west-central Wyoming. This is one of the best places to find this species, with lots of good habitat for the grouse and other sagebrush specialists.

View from our camp, 2011

It’s also a stunningly beautiful place to get to work. Our camp looks out on the eastern face of the Wind River Range, a spine of the Continental Divide near Lander, Wyoming. Although we are less than an hour from town, we feel like we are in the middle of nowhere. We can see distant lights from Riverton, and a bit of city glow from Lander, but otherwise we have this patch of heaven almost to ourselves.

Driving through Nevada

The first challenge we face is simply getting all of our gear out to the site. This takes careful packing followed by a long drive through the lonely spaces of Nevada and Utah.

Work trailer arrives.

Once we’ve landed in Lander, the next step is to get the camp set up. Besides our RV, we have to rent a work trailer, as well as propane service. Thankfully we have electricity; there’s a line that runs the well pump for the cattle water tanks in the summer that we can use in the spring (the cows don’t come up until May when we are done with our research- we’ve been fortunate to coordinate with the local grazing leaseholders on this).

 

Propane tank arrives- nice to have heat, hot water, and cooking capability without having to run into town to fill canisters all the time.

Home sweet home.

Looking for tracks or poop on the lek.

Our first field technicians arrived on March 3rd, and the following day we were out at dawn looking for grouse on the leks. It’s still very early in the season- at least 2 weeks before the earliest sage-grouse mating we’ve ever recorded during our years out here. This means some leks will still be empty while others will have a few males starting to set up territories. Our first visit is to the most accessible lek called Chugwater Lek (in our area each display ground has a unique name). We didn’t see any birds, and a search of the lek surface showed no fresh sign. Our first birds didn’t show up here until March 7.

Scanning Cottontail Lek to count grouse.

Cottontail Lek is our largest lek, and on our first visits there we did find males starting to set up territories. This was the first chance for the crew to see the courtship display, and they were suitably impressed (just wait until they get to experience it from a blind down on the lek instead of a distant look-out point!)  We were also treated to a large herd of pronghorn moving past in the early morning light. This was also a new animal for some on the crew. They are taking to the western wildlife quickly, although some are still getting used to the idea of a landscape without any trees!

Pronghorn Antelope near Cottontail Lek

Over the next couple of weeks we will be gearing up for our data collection, which will involve setting up a grid of stakes on the lek to help with territory mapping, installing microphone cables on the leks, starting to get photographs of the males to distinguish them, and hopefully capturing and banding some as well.

Sage-Grouse leks: One of the greatest shows on Earth!

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I’m kicking off my blog for the 2013 research season with a brief description of what makes sage-grouse such a great bird to study for someone interested in animal behavior and evolutionary biology.

Male sage-grouse courts a female.

One of North America’s most spectacular birds is also a species that not many people have seen. I’m referring to sage-grouse: I study the more widely distributed greater sage-grouse (Centrocercus urophasianus); I have yet to personally see the less common Gunnison’s sage-grouse (Centrocercus minimus), but that is definitely on my wish list. Given the spectacular plumage of a male sage-grouse in display, why are these birds so hard to see? A quick look at a female sage-grouse tells you the girls are built for crypsis- well adapted to blending in with their environment. For most of the year male sage-grouse also play the hiding game, so unless scared into flight they may pass unnoticed. Yet for a couple of months in winter and spring, males come into their traditional display grounds (called leks, from a Swedish word for “child’s play”) and put on one of the greatest shows on earth. These leks are often in fairly remote areas, and males typically attend them only in the early morning hours. Both of these reasons help explain why getting a look at this spectacle can be a bit of a challenge.

 

These unusual breeding clusters have captivated not only birders but evolutionary biologists as well. In about 90% of birds, both parents provide some care for the nestlings. In those cases, females are often choosing their mates at least partly on the material benefits they get from this partnership, whether it be the quality of the male’s territory or his ability to provision the female during incubation or the chicks once they’ve hatched. [Note- in many birds males and females mate outside of this pair bond, but that is a tale for another day]. Lekking species are therefore unusual among birds in that males don’t form a bond with their mate nor provide any child care. Scientists are still trying to unravel some of the puzzles that leks represent. Why do males cluster together to display, rather than searching around for females, following females around, or spacing themselves farther apart and defending larger territories like most other birds do? If males aren’t helping raise the kids, why are females so picky? What benefits do females get from choosing one male instead of another? And given that females often pick only a few among the many males on a lek, why do the “loser” males bother to stick around?

(This is a 3-hour time lapse video of the lek. The males appear as small black-and-white specks at the bottom of the frame)

Lekking animals also tend to be high on the charisma scale. Besides the spectacular sage-grouse and their cousins the prairie chickens and sharp-tailed grouse, other lek-breeders include some of the most beautiful and acrobatic birds out there, including birds of paradise, neotropical manakins, peacocks, cock-of-the-rock, some hummingbirds, and ruffs. When we see a species in which males are larger or more colorful than females, we presume these differences are related to an evolutionary process called sexual selection, where one sex- often the males- competes either directly for access to females or indirectly by producing the best advertisement among the other males. This certainly seems plausible for sage-grouse; not only are adult males almost twice the weight of females, but they have a range of specialized feathers, brightened skin patches, and other unique structures.

Male sage-grouse showing his inflated vocal sacs.

The distinctive air-filled vocal sacs are actually part of the digestive system; once inflated with air, powerful muscles just under the skin help move and shape the them during display. In spite of decades of research and routine collection by hunters, we are still finding surprising structures in these birds. Just recently we discovered that male sage-grouse have an almost songbird-like syrinx (sound-producing organ analagous to the human larynx) capable of producing two tones at once. All of this adds up to the bizarre appearance of the male that has presumably evolved through sexual selection- the males with the more elaborate versions of these unique features get to mate with more females and pass on more copies of their genes to the next generation.

 

These differences between males and females extend to courtship behaviors as well; males and only males have a characteristic “strut” display. A male’s strut serves to attract females to the lek from across the landscape, to woo females once they are on the lek, and most likely to help claim their small patch in the midst of all the other males. Each display lasts about two seconds and involves coordinated movements of the wings and body.

For sage-grouse, courtship is not just a visual spectacle. Males produce a variety of sounds during the strut display. The first two notes actually are not vocalizations at all, but instead made by rubbing stiff, pointed breast feathers against the inside of the wings. This is somewhat analogous to how crickets chirp. Making sounds with feathers may sound unusual, but it has evolved repeatedly in birds. Some common species in the Bay Area that do this include Mourning Doves (the ‘wee-wee-wee-wee’ made during take off) and Anna’s Hummingbirds (the loud chirp made at the nadir of the male’s dive display).

Spectrogram of a sage-grouse display. The two feather-produced 'swish' notes occur at about 2.6 and 3.6 seconds. The first low frequency 'coo' note is at 4 seconds, and is followed by the pop-whistle-pop at about 4.3 seconds. You can hear this in the video above.

The remaining notes are true vocalizations made by the syrinx, although unlike most birds they are made with the beak closed. These sounds start with a series of three low frequency ‘coo’ notes, and conclude with an up-down-up ‘whistle’ note sandwiched between two staccato ‘pops’. You can see these in the spectrogram- this is a visual representation of sound and you can read it much like reading music, with time progressing towards the right, pitch becoming higher towards the top of the figure, and the darkness representing something like loudness. Females may care about some very subtle differences in these sounds when they are looking for a high quality mate. Researchers have compared sound recordings of successful and unsuccessful males and found differences in the relative timing of the two ‘pop’ notes, and maybe the loudness of the whistle. What is amazing is that the differences between ‘Mr. Right’ and ‘Mr. Wrong’ are on the order of less than a tenth of a second. Females may have quite the ear when it comes to picking their mate!

 

That’s a quick introduction to sage-grouse in the spring. I feel extremely lucky to have heard and seen this show for the past several years as part of my research at the University of California, Davis. Along with Professor Gail Particelli, graduate student Anna Perry, and our intrepid field crew, we will be conducting research into several aspects of sage-grouse behavior and ecology from our field site just east of the Wind River Range in Wyoming. Over the next couple of months I’ll be discussing what it takes to set up a camp like this, how we use new technologies (including robotic birds!) to study courtship in this species, and review some of the conservation studies out of our lab. I hope you’ll join me for our 2013 field season!

Re-posting Field Crew Advertisement

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For a variety of reasons including wanting to expand the size of our crew, we are looking for an additional one or two assistants for our rapidly approaching field season. Dates potentially a little flexible, but we really need people comfortable driving an ATV (even better if received agency training or certification). Feel free to contact me with any questions.

 

 

Anyway, here’s the revised advertisement:

FIELD ASSISTANTS (1-2) needed approximately March 3 – May 5 (dates potentially flexible) for investigations of the behavior and ecology of Greater Sage-Grouse near Lander, Wyoming and the scenic Wind River Range.  The projects are part of a larger effort in Prof. Gail Patricelli’s lab at UC Davis to understand how sexual selection shapes sage-grouse display behaviors- see the following websites for more information (http://www.eve.ucdavis.edu/gpatricelli/) and (http://www.alankrakauer.org). Assistants will use video and audio recording technology to support an NSF-funded study of courtship dynamics and display plasticity on the lek. Duties include maintaining camera and acoustic monitoring equipment, observation of basic courtship behavior and lek counts, GPS surveying, habitat characterization, assisting in the capture of adult sage-grouse, data entry, and some computer and video analysis. Assistants must be flexible in their needs and comfortable living and working in close quarters in a remote field station, and able to work in adverse field conditions (mainly MUD and COLD).  Work will be daily and primarily early in the morning, with afternoon and night work required as well.  Applicants must have a valid driver’s license, basic computer skills, ATV experience (ideally with formal safety training or certification), and have succeeded in at least one field biology project in the past. Wilderness First Aid or First Responder, and prior experience spotlighting for sage-grouse, preferred but not required. Must be able to show proof of United States employment eligibility. Assistants will receive $600/mo plus room and board, but need to provide their own transportation to Lander and their own personal gear.  Please send a cover letter, resume, and contact info (email and phone) for two (2) references to: Alan Krakauer, Department of Evolution and Ecology, University of California Davis, One Shields Avenue, 2320 Storer Hall, Davis, CA 95616, or preferably by email to ahkrakauer [at] ucdavis.edu.  The positions will remain open until filled, and review of applications will begin immediately.