Eavesdropping ears: mule deer listen to marmot cues

When it comes to Kingdom Animalia, we’re not the only ones that can tap into the conversation!

Our study conducted this summer at the Rocky Mountain Biological Laboratory (RMBL) suggests Mule deer (Odocoileus hemionus) tune into marmot (Marmota flaviventris) alarm calls for hints of nearby predators.

Photo credit: Jenn Smith

Previous scientists noted that mule deer reacted to marmot alarm calls, and we saw this as an opportunity to study interspecific communication in animals of different size, vulnerability and defense mechanisms.

Interspecific communication, or eavesdropping, is when an individual of one species receives and responds to a signal from another species. What’s that information good for, anyhow? Well, if you’re a vulnerable animal foraging, intercepting a pertinent warning can help save your life! Eavesdropping is a useful tactic to learn and can change foraging and antipredator behavior, protection seeking, and group characteristics.

Deer and marmots live in similar areas, and coyotes and potentially mountain lions prey upon both. Therefore, we hypothesized deer would respond to marmot alarm calls versus a common bird song. To test this hypothesis, we conducted a playback experiment.

We recorded mule deer behavior in response to either the song of the mountain white-crowned sparrows (Zonotrichia leucophrys; control), or a marmot alarm call. This was your typical field biology research: wake up before dawn, strap a speaker to your backpack, and head out to track deer, microcassette in hand. Of course, finding deer was usually easier said than done. I quietly recorded the deer behavior 30 seconds prior to and after the sound was played using a prewritten ethogram with typical deer behavior. That information was then analyzed in JWatcher for patterns.

Hiding in veratrum on the search for unsuspecting deer

Turns out for the marmots at RMBL, the marmoteers aren’t the only ones listening in. We found that deer near human settlements had a significantly different response to marmot calls than sparrow songs. Any individuals who heard the call typically became alert and stayed vigilant longer; whereas, those who heard the control were more likely to look and then continue foraging. Deer far from people showed similar responses to marmot calls and sparrow songs probably because they aren’t habituated to a person being around.

Our results are interesting and unique because we have evidence for eavesdropping in animals that are very different in size and vulnerability. These deer have found a potentially reliable source of information through marmots and can use that to either take off into the woods or allocate more time foraging.

There is a lot more work to be done in this field! Future studies can use a remote speaker and camera to study how deer farther away from human settlements react to calls, or how they react to the alarm call of a sympatric species that doesn’t share a predator with them. Perhaps even a study looking at fitness could be useful to know how beneficial eavesdropping is for individuals and populations. The list could go on…

If you’d like to get a more detailed review of this paper, take a look at a copy here.

Meet Team Marmot: Mega and Lawrance

Hello fellow marmot lovers, field biologists, and any other souls out there. We are among the newest additions to Team Marmot.

My name is Mega Patel (pronounced just like it sounds) and I am a second year Biochemistry major at UCLA. I joined Team Marmot because I love all branches of the sciences, and the Blumstein lab seemed like a great place to expand my knowledge on science outside of chemistry. And my name is Lawrance Chung, a third year Biology major at UCLA. I decided to join Team Marmot because I secretly want to be a marmot. Joke aside, I felt that this lab would be a wonderful opportunity to expand my research experience.

Sorting the poop!

Since September 2011, we have been a part of the Blumstein lab. For the first few weeks we did some of the dirtier work, but we know that the resulting data is worth it. We sorted through fecal samples, from the RMBL group, the tagged wild marmots in Colorado, and the captive group, a control group housed at Colorado State University by Greg Florant from which experimental validations of our assays were carried out. Our work is done directly under the mentorship of Dr. Jennifer Smith (shown below).

Jennifer Smith with a captive marmot at
Colorado State University

The purpose of sorting these fecal samples was to get an accurate measurement on how stressed each particular marmot is on a day-to-day basis. While hair samples can provide an idea of how stressed one was months ago, and blood can be used to measure how stressed a particular individual is within a matter of minutes (reflecting trap stress), fecal samples can actually measure how stressed the marmots were yesterday (before the trapping event), which is exactly the kind of data this lab wants to add to its database.

Greg Florant with a captive marmot at

Colorado State University

Like you might have already guessed, we measure the “stress” level of marmots by measuring the concentration of glucocorticoids in their processed fecal samples. The process begins by sort through the fecal sample to obtain a pure sample. This means removing the different fibers, seeds, and occasionally rocks from the sample after creating a nicely mixed bag of feces that we fondly liked to call poo-dough. Then after a single sample was cleaned,it was carefully weighed to 0.20 grams. The accuracy of the weight was very important and we took great care in measuring the samples as close to 0.20grams each as we could. This precision was necessary so that the resulting concentrations of the glucocorticoids could be compared among different marmots. A larger weight could mean a higher concentration, causing the data to reflect the marmot being more stressed than it actually was. In addition, each marmot sample was carefully labeled with an unique ID to ensure that samples from different marmots were not mixed.

Currently we are sorting through and labeling blood and plasma samples from different marmots dating as far back as 2002 and have been preserved in a -80 ˚C freezer. The sorting process involves going through and individually labeling each vial with a unique ID. This sounds much easier than it is because we have to first be able to match up the vial to the correct entry in our database, which does not always happen as sometimes the dates or time will be off. Then comes the tricky part of trying to write on a frozen vial, however, with the help of Emery and Rachel, we have made great progress and will be done within the first week of next quarter.

It has definitely been a wonderful quarter with Team Marmot and we look forward to the next one! Happy Holidays everyone!