Using playback of territorial calls to investigate mechanisms of kin discrimination in red squirrels

A little while back, I did a Master’s degree at the University of Guelph with Prof. Andrew McAdam. I worked on the Kluane Red Squirrel Project, a collaborative project between several universities in Canada and the U.S. This long-term project was started nearly 30 years ago by Prof. Stan Boutin at the University of Alberta. The project has involved many undergraduate, graduates, and post-docs over the years studying a variety of ecological and evolutionary questions on a population of red squirrels in Kluane, Yukon.

  • A red squirrel in Kluane, Yukon, one of the individuals in the study population.

For my Master’s project, I was interested in red squirrel territorial behavior and the vocalizations, known as rattles, used to defend their territories. Red squirrel rattles are individually unique and have been shown to be used to discriminate kin, though the mechanism underlying this ability is unknown. In a recently published paper in Behavioral Ecology, I sought to distinguish between the mechanisms of ‘prior association’, where animals learn the phenotypes of kin they associate with early in life, and ‘phenotype matching’, where animals use a template to match phenotypes, thereby allowing them to recognize kin without an association early in life. I recorded rattles from squirrels in the field, and used those recordings in playback trials to measure the behavioural responses of squirrels to rattles from familiar kin, unfamiliar kin, and non-kin. One of the major benefits of the Kluane Red Squirrel project is that there is pedigree information for each squirrel, which means that we know who their mother and father is and who their siblings are. Without this information, this project would not have been possible, and full pedigree information is difficult to obtain for wild populations of animals.

  • Recording rattles from squirrels in the field to use in the playback trials

For red squirrels, familiar kin consisted of pair of squirrels that shared a natal nest (e.g. mother-offspring pairs and siblings from the same litter), and unfamiliar kin consisted of pairs of squirrels that did not share a natal nest (e.g. father-offspring pairs, siblings from different litters). Initial analyses revealed that red squirrels did not discriminate between familiar and unfamiliar kin, but also did not discriminate between kin and non-kin, despite previous evidence indicating this capability. Post-hoc analyses showed that a squirrel’s propensity to rattle in response to playback depended on an interaction between relatedness and how the playback stimuli had been recorded. Rattles used as the playback stimuli were either recorded from squirrels as they moved freely around their territories (unsolicited), or from squirrels as they were released from a trap or in response to a broadcast rattle (provoked). Red squirrels discriminated between rattles from close kin (relatedness coefficient of at least 0.5) and rattles from less related kin or non-kin (relatedness coefficient of less than 0.5) when the rattles were recorded from provoked squirrels. Squirrels did not exhibit kin discrimination in response to rattles that had been recorded from unprovoked squirrels.

This figure show the probability of a rattle response from the subject squirrel during the playback period by relatedness coefficient calculated from the pedigree and the collection method of obtaining the rattle stimulus. Unsolicited rattles were recorded from squirrels moving freely around their territories (n = 67 trials), and provoked rattles (n = 38 trials) were recorded from squirrels as they emerged from a live-trap or from squirrels responding to a rattle playback

This is potentially quite interesting, but it is important to note that this relationship was identified through exploratory post hoc analyses and needs to be tested more rigorously. If these results are robust, however, they would suggest that a squirrel’s physiological state might influence the structure of its rattles, including those individually distinctive structural features that are presumably used in discrimination. This raises interesting questions about what kind of information may be contained in the rattles and suggests that rattles may reflect the current state of stress or aggressiveness of the squirrel.

Photos and post by Julia Shonfield

Julia Shonfield, Jamieson C. Gorrell, David W. Coltman, Stan Boutin, Murray M. Humphries, David R. Wilson, Andrew G. McAdam. 2016. Using playback of territorial calls to investigate mechanisms of kin discrimination in red squirrels. Behavioral Ecology arw165. doi: 10.1093/beheco/arw165.

The abstract and a link to the full text can be found here:

If you are unable to access the article but are interested in reading it, you can email me at julia.shonfield@gmail.com and I can provide you with a copy.

Field Assistants Required 2017- Kluane Red Squirrel Project, Yukon, Canada

We are looking for volunteers to assist with fieldwork for a number of different time periods: (a) 10 March- 30 April/15-May (b) 1 May-15 July, and (c) 1 September – 15 October. We will also have two positions that extend from 10 March to 15 August.

The positions are part of a long-term study of red squirrel ecology, evolutionary biology and physiology. As a member of the study, assistants will be involved with monitoring the reproduction and survival of individuals. Fieldwork will involve live-trapping and handling of animals, radio-telemetry, behavioural observation, and climbing trees to find young in nests. Some positions will also require handling for physiological assays (e.g., blood sampling) This is an excellent opportunity to gain experience working with a collaborative research team on a long-term study of a wild mammal.

All fieldwork is carried against the beautiful backdrop of southwestern Yukon, Canada. We will be staying at a rustic field station two hours from Whitehorse, and ~30 min to the nearest town (Haines Junction). Food and accommodation are provided. Volunteers are required to provide for their own travel to Edmonton, Alberta; however, travel from Edmonton to the field station (and back again!) is provided.

Training will be provided and no experience is necessary. An on-site head technician will coordinate the project, in coordination with the PIs. Candidates should have an interest in a number of the following (the more the better!): ecology, evolutionary biology, wildlife, field biology, and animal behaviour. The field camp is remote and low tech (no showers, cell phone service, or internet), so successful applicants must enjoy the outdoors and be able to remain a positive and responsible team member under relatively isolated and demanding conditions. Candidates must be in good physical condition, be willing to climb trees, and have an enthusiasm for learning. We work on ‘squirrel time’, which often involves long work days; as such, applicants must have a strong work ethic. That said, the atmosphere at squirrel camp is friendly and inclusive, and this area is one of the most beautiful in Canada. All nationalities are welcome.

If you wish to apply for one of these posts then please send a CV with a cover letter and contact details for three references (with e-mail addresses), by email to Brynlee Thomas (brynlee@ualberta.ca), by January 10, 2017. Please also indicate the time period(s) you are interested in.

An end of season thank you from Andrea Wishart, KRSP Ph.D. student and 2016 fall head tech

 

screen-shot-2016-10-19-at-4-12-22-pmMount Decoeli across from Kloo Pond (close to the KRSP camp). Photo taken by Andrea Wishart. 

The H-bars have been hung up and the bright orange trapping vests have been tucked away, and with that, another squirreling year has come and gone. We tracked squirrels through the seasons, from the arrival of spring core crew in early March to the last squirreler standing in mid-October. A huge thank you to all of the hard working people, from the newbies learning to squirrel for the first time, the returning techs who showed us the ropes, and all the other KRSP students who helped guide and support us!

As someone who arrived at our beloved Squirrel Camp a brand new squirreler in March as bright eyed and bushy tailed as any of our squirrels, and who ended the year as fall Head Tech, I would personally like to thank everyone who trained me early on and who helped me make my job in the fall so much easier and fun! Thanks to Brynlee for coordinating logistics from Edmonton and making sure we always had working equipment (and drained dunnies…), Eve for doing a fantastic job as Head Tech throughout the summer, Jess for training us on midden cone counts and keeping us motivated throughout, and the KRSP PIs for keeping this project rolling all these years (and especially Stan, who also gave us the gift of insulated floors this fall). Squirrel Camp is an incredible place, and everyone who comes through knows that it’s the people that are a part of it that make it that way.

Raise a spruce cone to 2016!

– Andrea Wishart

 

Reflections of the 2016 season working at squirrel camp

Time for a retrospective; I may be writing this from back south in Guelph, but looking through these photos is making me feel like I’m right back at Squirrel Camp again. I’m a new contributor to this blog; I’m just starting my MSc on the project, but I was up in the field for the last six months working as a technician on the core data collection. This was actually my second year up at camp, but my stay was substantially longer and this time I got to overlap more with the winter crew, which was awesome.

Luckily for me, I really love the cold and snow. If that weren’t the case, then Yukon in March might not have been quite as enjoyable as I found it. There were definitely some difficulties that came along with – having to snowshoe everywhere you walk, not being able to feel your fingers 75% of the time – but we also got so many quintessential Yukon experiences, like volunteering at a sled dog race and seeing the northern lights nearly every night.

jack_sled

The worst part of the year at camp, in my opinion, is the transition season in the late winter when everything is melting and there are mud and puddles everywhere you look. That passes, though, and then all the leaves emerge seemingly overnight and it’s spring out of nowhere.

And with spring comes babies – lots and lots of baby squirrels. It’s the best part of being at camp by far, getting to tag and weigh all the juveniles. Finding the nests and retrieving the pups usually isn’t too hard, but sometimes it takes a little more effort or you get a couple surprises. Twice this year I was looking into a nest and had northern flying squirrels jump out at me instead of the red squirrel pups I was expecting, which is (as you might expect) quite the surprise.

jack_babysquirrel

The first week of May marked the last time I remember seeing a star at night until the beginning of August. Summer in Kluane is a time of early mornings and late evenings, and if you don’t adjust to sleeping while the sun is still up then you’re going to end up very sleep deprived. Although I missed seeing the aurora at night, there’s something to be said for never needing artificial illumination for three months straight.

It wasn’t all work, all the time, at camp this year. We made the most of our days off and Friday and did as many hikes as we could. One of my favourites this year was Sheep Mountain overlooking Kluane Lake – I had tried it last year and had to stop partway up, so I was excited to do it properly and get all the way to the summit. We did it mid-August, so not only was it a beautiful view but it also made an excellent send off for some of the technicians that left soon after that.

jack-mtn

All in all, I think these past six months in Kluane were some of the best (and most sleep deprived) I’ve had in a long time. I’m already looking forward to heading back up again this coming su mmer to work on my own research.

Hoping all your squirrels are trappable,

Jack Robertson

MSc student, University of Guelph

Old squirrels are conformists

DSC_0016

A squirrel in the ‘Thunderdome’, photo by Amanda Kelley.

Biologists working in the Yukon have discovered that young red squirrels’ personalities become more similar over time. “Young squirrels have really extreme personalities,” explains lead researcher Amanda Kelley. “But as they mature, their behaviour becomes more average. Really aggressive squirrels tone it down over time, while meek ones become more hostile.”

The researchers assessed squirrel personality by capturing individuals and temporarily placing them in a ‘thunderdome’, essentially a white box with a clear lid. “We video the squirrel’s behaviour in this new environment, and after a set amount of time, show the squirrel a mirror.” The bushy-tailed rodents believe the mirror to be another squirrel of the same size and respond accordingly.

DSC_0277

Amanda Kelley with the Thunderdome in the background, photo by Amanda Kelley.

Squirrels react to the mirror in very different ways. Remarks Kelley, “Some individuals are really confrontational and immediately rush the mirror, tapping it with their little paws, while others retreat to the furthest corner and avoid eye contact.” These thunderdome trials give insight into an individual squirrel’s personality. The mirror test reveals how aggressive a squirrel is, while the time a squirrel initially spends scurrying about gives insight into how active it is. Kelley’s team conducted personality tests for each squirrel at two ages: first, when newly emerged from its mother’s nest, and again eight months later, when squirrels were fully mature.

As with aggression, the researchers found that a squirrel’s activity became less extreme with age. “The busiest squirrels slowed down the most. In fact, very few increased at all,” says Kelley. This suggests that, on the whole, squirrels mellow with age.

A squirrel checks himself out in the Thunderdome mirror, photo by Amanda Kelley.

Kelley and her colleagues hypothesize that having flexible personalities is important for young squirrels. “After a juvenile leaves the nest, it has to strike out on its own and find a territory,” says Kelley. “It’s a very dangerous period, where certain behaviours can have severe consequences.” As squirrels mature, extreme personality types may carry a disadvantage, meaning their success may depend on finding a happy medium between keeping their cool and sticking up for themselves.

The findings were published in the journal Behaviour. Contact Amanda Kelley, Field Coordinator for the Kluane Red Squirrel Project, for interviews or more information.

Canada Day

DSC_0951 Think of a float in a parade. What comes to mind? Streamers, balloons, bright colours, people in costumes, loud music, confetti…maybe not an F-250 covered in cardboard. But when at Squirrel Camp, one must make do with what one has available for decorations, and this mainly consists of cardboard boxes and Sharpie ink. Our monster of an F-250, dubbed “Sasquatch”, got all dressed up to be included in the Canada Day parade in Haines Junction this past Tuesday. Sasquatch found itself with a lovely large pair of cardboard squirrel ears complete with ear tags, whiskers made of big white pipe cleaners on its headlights, and even an improvised squirrel tail affixed to the trailer hitch (the success of making an accurate taDSC_0954il was questionable, but after inhaling as many Sharpie fumes as we did in the process of its creation, we felt it had to be used).

Our bizarre squirrel/truck hybrid made its way along the two main streets of Haines Junction (this essentially encompasses the entirety of the 4th largest municipality in the Yukon) amidst many other impressive floats, including the truck behind us complete with a swimming pool in the bed! Needless to say, many efforts were made to soak the squirrelers in the back of Sasquatch. I am proud to say that I escaped, but I am not sure that everyone was so fortunate. Other participants in the parade included the Lions Club with a massive, colourful float pulled by a tractor, the Haines Junction fire department, a number of young cyclists and several animal participants. A very well-dressed dog with Canada-themed anklets later won an award for being so sporting.

The parade was followed up by a delicious barbecue thanks to the Lions Club, plenty of fun and games out on the lawn, cotton candy and even the unveiling of a pair of new murals made by the local elementary school. For a town of less than a thousand people, Haines Junction really pulled out all the stops this July 1st! It was an incredibly fun atmosphere, and a couple of us squirrelers even joined in on a nearby informal football game. When I say “informal”, I mean lacking in rules and run by twelve-year-old boys. And so Squirrel Camp did not let go of childhood this Canada Day! We hope you enjoyed your own festivities on July 1st this year. Squirrel Camp will be back again for next year’s parade, with plans to stockpile some cones to use as a more natural, boreal confetti.

–          Sarah Nason, U of Alberta