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.

It is hard work for animals to obtain food from the environment. They must move quickly to capture their prey or travel long distances to find suitable plants to eat. It is also a lot of work for animals to digest the food they obtain and then allocate food nutrients to maintaining their own health. The total amount of work an animal does per day is termed its daily energy expenditure. Scientists are interested in measuring the daily energy expenditure of animals in their natural environments. To do this, researchers use the fact that animals breathe in oxygen (O2) and breathe out carbon dioxide (CO2) and water (H2O). Similar to the last time that you ran up a couple of flights of stairs, when animals work hard, they breathe in more O2 and breathe out more CO2 and H2O. The technique uses special non-toxic water that is injected into animals. It estimates daily energy expenditure by measuring the amount of CO2 animals breathe out over a multi-day period. Regular water is composed of a ratio of two hydrogen atoms (H) to one oxygen atom (O) to make H2O. In the special water used in this procedure, the ratio between H and O is the same, but a proportion of the O and H atoms are naturally labelled O* and H*. For the technique, the special water is injected into the animal. The O* and H* molecules naturally mix with the other O and H atoms in the body water. A blood sample is collected to determine the initial concentration of O* and H*. Animals are released after the initial blood sample and behave normally for about two days. As they are busy working over this time interval they breathe out O* atoms in both CO*2 and H2O*, whereas the H* atoms are only breathed out through H*2O. The animal is then recaptured and another blood sample is collected. Scientists are able to quantify the amount of CO2 expelled, and thus get a measure of how hard the animal worked by comparing the ratio of O* and H* in a final blood sample to that in the initial blood sample. If the animals worked hard and expelled a lot of CO2 there will be a greater difference in the concentration of O* and H* between the initial and final blood sample. The amount of CO2 expelled can then be converted into an estimate of the daily energy expenditure of that animal.

-QF

Radio Telemetry

Definition
Telemetry (tele = distance, metry = measurement) refers to measuring from a distance. "Radio" telemetry refers specifically to telemetry in which information is transmitted over VHF radio waves. Although several aspects of an animal's biology can be measured remotely with telemetry, we use this tool specifically to measure a squirrel's position in space.


Components
There are three components to a radio telemetry system.:

1. A transmitter is worn by the animal subject. It transmits a pulsed signal (every 1.5 seconds) as a VHF radio wave. Squirrel transmitters weigh 4 grams and are worn around the neck.



2. A receiver receives the radio signal and translates it into something we can interpret such as an audible beep. The receiver can be tuned to receive specific radio frequencies within a broad range, thus one receiver can be used to identify and track multiple animals whose radio collars transmit at different frequencies.


3. An antenna amplifies the radio signal being received. A "directional" antenna receives the radio signal with different sensitivity (gain) depending on the orientation of the antenna - the beep is loud when the antenna pointed toward the animal, but becomes increasingly softer as the antenna turns away from the animal.



Techniques
In Squirrel Camp, we use radio telemetry primarily for radio tracking - following the radio signal until the animal is located visually. Starting at some distance from the squirrel, we travel in the direction in which the radio signal is strongest. As we get closer to the squirrel, the radio signal increases in strength, i.e. the beep gets louder, and we can reduce the sensitivity (gain) on the receiver for better sound resolution. We home in on the squirrel until we make visual contact. This gives us the squirrel's exact location in space, and allows us to observe its behavior at the time. Experienced researchers can locate squirrels in less than ten minutes with this technique.


Occasionally, we use triangulation to locate squirrels from a greater distance. Triangulation involves recording the direction from the observer to the squirrel as a compass bearing from two or more observer locations. These bearings are then plotted as lines on a map, which intersect at the animal's location. Unlike radio tracking which gives an exact location, triangulation involves some estimation error, but can be kept small by experienced researchers.


On foot in the boreal forest, we can detect the radio signals from squirrel radio collars from distances of about 300 meters. Antennas positioned higher can receive signals from greater distances. Common tactics to increase the range involve gaining elevation, and include climbing hills and trees, or when these are not available, standing on your vehicle.



Applications
Radio telemetry has many applications in wildlife biology. Telemetry-based analyses we conduct on the red squirrel project include:

Resource use - nest sites, feeding locations
Habitat selection - used sites chosen from among those available for use
Survival - Longevity, location and cause of death
Movement patterns - sequential locations of moving animals such as dispersing juveniles
Activity patterns - timing and duration of activity and sleep, nest use
Behavioral observation - focal sampling for determining diet, mating choices, caching behavior
Home range analysis - drawing polygons around a large set of mapped locations


-MCA

Lots of nests last week, but we're still not at the peak. That will come this month as Kloo, Sulphur and Chitty ramp up and coincide with Agnes's, Lloyd's and Joe's nest 2s. Julia and Jamie did 6 nests on Lloyed one day (1 in the morning 5 in the afternoon) and then Julia and Kate pulled of 5 nests the next day spread across two grids. 5 nests in an afternoon might be a record.

Beth and Dieter return from nests on Chitty.


Crystal climbs for pups on Agnes.

Agnes pup


Mom moving a pup to a new nest.

-Ryan

A Lynx joined me in watching a mating chase today. It just sauntered up and sat down about 15 yards from me and went into stealth mode. Sat motionless for about 45 minutes with it's eyes closed but it's ears were busy listening to every sound. The squirrels barked for a while but eventually carried on almost like normal, but they were pretty cautious about going near the ground. I got pretty excited a few times when one would stray close, but they never got close enough for the lynx to strike. I think I was probably cramping the lynx's style, as I couldn't stay nearly as still and was constantly turning around to look at squirrels, and it shot me a few looks to say as much. The lynx would just aim it's ears towards the squirrels and very slowly turn its head (with eyes mostly closed) when they approached. Eventually it gave up and took off on its usual loop through camp.

The aloof cat stare, telling me to quit fidgeting.


Lynx sat like this for a long time, eyes closed and ears perked.


A yawn, just before taking off.


Lynx have serious reach.


Check out the size of those feet!

One last look at the meals that could have been.

Lynx are showing up everywhere this spring. We've been seeing fresh tracks every day Lynx every other day. There is some speculation that the lynx are extra hungry because the snowshoe hares are in decline, but I'm not so sure. In any case it's exciting sharing the grids with the big cats.

Lynx on Kloo

Still a few hares around, actually I haven't really noticed a decline.

The other day I stumbled upon a lynx eating a squirrel! I was radiotracking a Kloo female (to see if she was in estrus) and she led me right to the lynx. Turns out she was in estrus today and the unlucky male was likely distracted by that.

"What squirrel?"

I think that's the liver, anyone know why the lynx would leave it behind?

Female squirrels come into estrus for one day and spend the whole day leading what we call a mating chase. The males involved in the chase seem to turn off their predator avoidance (Sara even had one run up her leg) so it's not too surprising that the lynx was successful. Also, the night before we had about 3 inches of snow which slowed the squirrels down a lot. They look a little like otters swimming through the powder.
After the lynx finished off the male it took off towards the negatives and found Abe and the mating chase that he was following. Abe had lost the female for a minute and by the time he found her she too had been caught by the lynx! The females are usually more cautious so I'm a little surprised that she was nabbed.

Radio collar untouched. Lynx ate the liver this time but left an arm?
-Ryan