Spring has arrived here at squirrel camp and it's pretty exciting! Chipmunks are up and running around all over the place, the ground squirrels are also out and there’s one that’s living under the data hut. The snowshoe hares have started to change colour and are mottled looking right now, with brown fur coming in on their backs and the white winter fur still on their legs and feet. Bear tracks have been spotted on Agnes but no one has seen any bears yet. More birds have arrived in the area including yellow-rumped warblers, varied thrushes, white-crowned sparrows, and buffleheads have been seen on Sulphur pond. Lots of raptors have been spotted lately including bald eagles, red tailed hawks, harriers, and goshawks. A large porcupine has been roaming around the huts in camp. Almost all the snow has melted and even the mud has mostly dried up. A few mosquitoes have been seen flying around, but they’re not a problem yet. Juvenile red squirrels have started to emerge from their nests on all of the food addition grids, and they seem to be running around and rattling all over the place. The May midden census is in full swing, and the crew has been assessing the activity and conditions of the middens on each grid as well as trying to determine which squirrel owns each midden. The crew went on another short hike along the Alsek valley last week. It was a beautiful warm sunny day and the highlight was seeing a moose swim across the river.
JKS


Blog photo 1: A vigilant least chipmunk


Blog photo 2: The squirrel camp crew hiking along the Alsek valley


Blog photo 3: A snowshoe hare with its summer and winter coat


Blog photo 4: A juvenile red squirrel eating a spruce cone

We did another peanut butter addition to the experimental grids starting on April 17. It was the second PB add for the core field crew, and it went much smoother than the first one we did when we arrived at camp in March. There was much less peanut butter spillage this time and the cookshack stayed remarkably clean, and no one had got really covered in peanut butter either. We heated the cookshack up to a sweltering 35C to pour out the PB. It was almost like having a sauna right in squirrel camp! Putting out the peanut butter in the buckets on the grids also went really well and it was all done in two days.


Stirring the PB – Dieter, Bastien, Krystal and Beth stirring the peanut butter in the steamy cookshack.


Pouring the PB - Beth, Dieter, and Krystal pouring the liquidy peanut butter into yogurt containers.

The crew at squirrel camp did the first big hike of the season up Sheep Mountain on April 11. There were 7 of us in total: Abe, Cate, Bastien, Jamie, Mark, Ryan and myself. We were up just as early as for trapping and it was the first day off where we worked just as hard as a normal day. Luckily we had great weather, there were a few clouds in the morning but they soon thinned out to reveal bright blue sky. It was pretty warm out and except for the very top of the mountain it was bare of snow. No need for snowshoes at all, even though some of us did lug them all the way just in case. We started the hike along part of the old Alaska Highway, a rugged wide path that hardly resembles a road at all anymore. We started hiking upwards and saw a few mountain sheep along the way, Ryan got some amazing shots of them.

It was a tough hike up and involved some serious rock climbing in spots. The further up we went the colder and windier it got, and near the top it was icy and snowy with a really brutal wind. The view from the summit was incredible and certainly worth the climb. Frozen Kluane lake to one side and massive snowy peaks on the other.


The best was yet to come though, as all of us slid down a snowy valley almost from the very top to about 2/3 of the way down the mountain. It was incredibly fun, like being a kid again on the best toboggan ride ever!


Eventually the snow started to get a lot slower and wetter, and we hiked the rest of the way down. The sliding down the mountain bit probably saved us a lot of time and we got back to camp in time to head into Haines Junction for burgers at the Kluane Park Inn.

Among the many differences between red (and other tree) squirrels and the other members of the squirrel family (Sciuridae), is that the tree squirrels don’t hibernate. While it may be asked how this relates to reproduction, for researchers monitoring the mating behaviour of red squirrels, the relevance is all too apparent. The compressed active season imposed by the hibernation period of ground squirrels, for example, requires that mating occur in a brief 1-2 week window in the spring following emergence. By contrast, as red squirrels are active all winter, they are able to commence mating earlier. Furthermore, as juvenile red squirrels require a territory and midden to survive, the earlier a female can start mating, the better.

The mating season at Kluane typically commences in either in February or March and continues until May or June. During this time, individual females are only in estrus (i.e., sexually receptive) for a single day. The relatively short receptive period of individual females and extended mating season means that few females are in estrus on any given day of the mating season. The first challenge for researchers at Kluane is consequently to find any receptive females. As we are still in the depths of winter in the Yukon for much of the mating season, this means heading out on snowshoes first thing in the morning and using radio-telemetry to locate our focal females. The female’s receptive period continues for the entire day until she retires to her nest when the sun goes down. While keeping track of the focal female, new researchers will quickly learn the significance of the term ‘mating chase’!

Because few females in the population will be receptive, individual estrus bouts attract great numbers of males. As the attending males jockey for position next to the receptive female she attempts to evade the queue and will travel great distances (at great speeds!) to do so. Keeping track of the squirrels, which are able to travel on the snow crust, while we’re sinking through on snowshoes can represent a challenge, to say the least. Researchers are granted temporary reprieve due to key points during the day when the female must stop traveling…to copulate. Copulations of red squirrels can occur in the tree, in snow tunnels, under downed trees or underground, but because they are stationary during this time, it means that, despite the extensive intervening travels, we are usually able to get a good census of the females mates. This research showed that females mate with among the highest number of males of any squirrel species so far studied (up to 13!).

Currently we are investigating what influences whether a copulating male will sire any of the resulting offspring. Although many of the litters are multiply-sired, on average, there are fewer offspring produced by the female than males she has copulated with. This means that some copulating males are unsuccessful in siring offspring. The high levels of multiple mating by females, and the detailed information that is collected as part of the Kluane Red Squirrel Project makes this a potentially very powerful system to address questions on male siring success and patterns of female choice.

The elaborate tail feathers of peacocks and impressive antlers of male deer have long fascinated those with an interest in animals. How could these traits evolve? Why are they dimorphic (usually only seen in the males of the species)? While the antlers could plausibly be an adaptation to thwart predators, surely this isn’t the case for the peacock’s tail feathers? The answer, it seems, lies in how individuals acquire mates. Females, by definition, produce few gametes (germ cells), but invest a relatively large amount of resources in each one. By contrast, males invest relatively little in individual gametes, but produce them in vast quantities. As a result, females (or more accurately their gametes) are limited, relative to males', and typically (although not always) males compete for reproductive access to females. It is now believed that the peacock's ornate tail serves to attract mates and the deer's antlers are used in physical combat among males for access to females. While these arguments (collectively termed 'sexual selection') have provided credible explanations for the evolution of these exaggerated traits, in some cases we are now faced with the complete opposite quandary. Specifically, why aren’t some animals, like the red squirrel, visually dimorphic? Put another way, if reproductive female red squirrels are a limited commodity, what traits are used by males to compete for access to them? Red squirrel males are only marginally larger than females, and don't possess either sexual weaponry like antlers, or ornamentation, suggesting that neither physical combat among males, nor visual attraction are important. At Kluane we are currently testing the hypothesis that the analogous trait to antlers and tail feathers in red squirrels is male behaviour. Because females defend individual territories, they are spatially scattered and males must search for reproductive opportunity. Could it be that the spatial abilities of male red squirrels represent their 'antlers'? To test this we following the males during the mating season to quantify their spatial behaviour and comparing their relative success, as the number of offspring that they sire. Should our hypothesis be supported, it could open the door to investigations of a far richer set of traits involved in sexual selection than has previously been appreciated.