Field Fun Friday

With the spring breeding season right around the corner, here is a photo of three Ferruginous Hawk chicks during a routine nest check last summer. Nick Parayko is studying these amazing raptors, in southern Alberta, for his Master’s project under Dr. Erin Bayne. Looks like fun!

Photo by: Nick Parayko




Male red squirrels kill other squirrels’ offspring to increase their own chances of having kids

I was walking in the Yukon one evening when I heard a commotion in the forest. At the time, I was working on my PhD under the supervision of Stan Boutin at the University of Alberta as part of the Kluane Red Squirrel Project. This meant that I spent a lot of time hiking on my study area monitoring the red squirrels that I was working with. It is common to hear squirrels calling because they are pretty chatty, but this commotion was different: this squirrel was very upset.

I walked quickly towards the calls, arriving to find a female squirrel yelling at her male next-door neighbor, who had intruded onto her territory. This is unusual, as squirrels live solitary lives and are usually respectful of each other’s boundaries. However, as I watched the male’s intentions soon became clear because within seconds of my arrival the male killed one of the female’s pups. I realized that I had just witnessed infanticide.


Infanticide is when an adult kills the young of their own species. I later found a second dead pup from the same litter, whose wounds were consistent with the infanticide that I had watched. The whole litter eventually died and their mother, the female I had seen yelling at the male, later had a second litter that summer. I was able to show using genetics that the male who killed the pup was not the father of any of the pups in the first litter, but that he was the father of all of the pups in her second litter.

This is an example of sexually-selected infanticide: this is when a male kills another male’s offspring in order to increase the chances that he’ll be able to father kids of his own when the female breeds again. I was fascinated by this behaviour, so I decided to explore it in more detail in our paper that was published today in the journal Ecology. I found evidence that this behaviour is linked to fluctuations in white spruce cones, the main food that red squirrels eat.

My colleagues previously showed that red squirrels can predict the future cone availability. The cones mature in autumn and at that time they can be harvested by the squirrels to be stored in a cache on their territory called a midden. Squirrel pups strike out on their own in the fall and during a bumper crop, called a mast year, they have a really good chance of surviving the winter because there are lots of cones for them to harvest and cache. Very few pups are able to store enough food in non-mast years so few of them will survive. Having access to cones is really key for pups to survive.


Squirrels are strategic and they can predict the future cone availability. During a mast year, the females will have more than one litter because they know that their pups will have access to cones once the fall arrives, and thus the pups will have a good chance of surviving. The females respond to masts in this way even though they breed in the spring but the cones aren’t available until autumn. In contrast, during non-mast years they will typically have only one litter.

I showed that litters die more frequently during mast years, suggesting that infanticide is more common during mast years. When litters die, their mother is more likely to have a second litter and will breed again sooner than if her litter had survived. So male red squirrels commit infanticide in mast years because the females will have that second litter, giving the males a second chance at fatherhood.



Post and photos by: Jess Haines

Effects of habitat quality and access management on the density of a recovering grizzly bear population

Clayton Lamb and colleagues from the Provincial Government of British Columbia and University of Alberta recently published an article in the Journal of Applied Ecology. This work investigates the factors driving the density of a threatened grizzly bear population in southern British Columbia.

Key results and conclusions:

  1. Heavily roaded areas had lower grizzly bear density.
  2. Closing roads to the public restored bear density in this area.
  3. Maintaining roadless areas in productive bear habitat is critical.
  4. Areas of low road density and high habitat quality occur as islands surrounded by either high road densities or poor habitat, limiting grizzly bear connectivity.

The Open Access article can be found here:

Infographic by Wild 49 Alumnus Kate Broadley, MSc.

An adventure in the far north – Deline, NWT

 Deline in the Sahtu region, NWT

One of the perks of graduate studies are opportunities to go to remote places that few other people get the chance to see. Earlier this summer I had the opportunity to travel to a remote fly-in only community in the Northwest Territory. The purpose of the trip was not directly related to my thesis, but to help start a local community bird monitoring program in two communities in the Sahtu region of the NWT, a project that the Bioacoustic Unit at the University of Alberta ( and my supervisor, Erin Bayne, is involved in. So in June, I travelled to Deline on the shores of the Great Bear Lake, and another graduate student, Michelle Knaggs travelled to Tulita on the MacKenzie River. Our roles were to bring autonomous recording units (ARUs) to the communities and start deploying them at various locations nearby with the help of locally hired guides.

The day I arrived in Deline was summer solstice and National Indigenous Day, and the following day was another holiday, Sahtu Day. The festivities involved a delicious BBQ cooked over a wood fire, a variety of games including egg tosses and obstacle courses, and a drum circle. These two days of local celebrations served as an excellent introduction to the community of Deline and gave me the opportunity to meet many of the locals.

In the week that I stayed there, I deployed the ARUs in several different locations around Deline. Though Deline is probably the furthest north I’ve ever been in Canada, the habitat was quite familiar. This area is still within the boreal forest, and the predominant habitat here is black spruce forest.

Black spruce forest in the area surrounding Deline

There were only a few roads and trails, so the access was relatively limited in the first couple of days because there was still so much ice on Great Bear Lake. Talking to people in the community, it was not that unusual to still have ice on the lake in mid-June, and it was largely dependent on the wind direction.

Ice on Great Bear Lake

Finally, the wind changed direction and pushed the ice out into the middle of the lake and away from the shores of Deline. In the last couple days I was there, I was able to get out by boat on Great Bear Lake and put some of the ARUs along the shore.

Boats along the shore of Great Bear Lake

The lake in the evenings was truly mesmerizing, flat as glass and incredibly clear, I could still see the rocky bottom several hundred meters out from shore. It was calm and peaceful being out in a boat on the lake in the evenings. The long days meant there was no rush to get things done before it got dark.

View of Deline from a very calm Great Bear Lake

There was a diversity of birds on the lake including Common Loons, and a variety of ducks such as Northern Pintails, Mergansers, and Scoters. In town, there were large numbers of Ravens and Herring Gulls.

A Raven and Herring Gull, abundant in town and especially at the town dump

It’ll be really interesting to see what birds we get on the recordings, the listening will be starting this fall. Since this area is so far north, it’s at the northern limit of the distribution of many birds. For me, it was a unique experience in the far north, one that I won’t soon forget.

  • Photos and blog post by Julia Shonfield


Field Fun Friday

A grizzly bear rubs against a tree in Clayton Lamb‘s British Columbia study area. Clayton uses hair samples from grizzly rub trees to identify individual bears and further our understanding of BC’s grizzlies. Bear claws are one way to identify the bear species. Black bear claws are short and have a darker color. Grizzly claws are long (about as long as human fingers!) and light-colored.

Photo by Clayton Lamb.

Squirrel Baby Boomers are Masters of Timing

New research and a great paper from the Boutin Lab and Kluane Red Squirrel Project!

Published in the journal Scientific Reports on 24 August 2017:
Hämäläinen A., McAdam A., Dantzer B., Lane J., Haines J., Humphries M., Boutin S.:
“Fitness consequences of peak reproductive effort in a resource pulse system”
DOI: 10.1038/s41598-017-09724-x

A North American red squirrel in search of spruce cones to cache away for the rainy (or rather: snowy) day. Photo by: Anni Hämäläinen.

For a squirrel baby boomer, timing is everything
It is mid-winter and the forest rattles with frenzied squirrel activity – they chatter and chase one another in ongoing negotiations about fleeting romance. This year, the stakes are high and the squirrels know it. Using cues unknown to us, they have correctly anticipated times of plenty in the coming fall, as the spruce trees in their forest are about to fill their branches – and the squirrels’ larders – with more cones than all the squirrels in the forest can eat. This kind of an opportunity comes once in a squirrel’s lifetime, as spruce “mast” seeding only happens every few years at an unpredictable frequency. When it happens, however, there is enough food around to support many more squirrels than at times of low cone production, and any babies born on the eve of such abundance will have a much higher chance of surviving the harsh winter ahead, relying on a pantry full of cones.

Evolutionary processes have ensured that the parents take full advantage of this prospect, because producing more offspring in such years can significantly increase the parents’ reproductive success and pass on those genes to future generations. Researchers working on squirrel populations of the Kluane Red Squirrel Project in the Yukon have previously discovered that squirrel females can produce multiple litters in the breeding season preceding a mast year, and “teen moms” are more common in those years, as yearling females are more likely to breed in mast years. For our latest study (Scientific Reports in August 2017), we analyzed the detailed breeding histories of female squirrels in those populations since 1986, and estimated how accurately squirrels match their reproductive efforts to the mast years. We then asked exactly how important it is for a squirrel’s fitness that their timing is right. To answer this question, we compared the total numbers of surviving offspring produced by those females that maximized their breeding efforts in anticipation of a mast year, relative to those who failed to do so.

To test the importance of the matching of mast years with high-intensity reproduction, we examined the annual number of babies a female produced over their lifetime. The typical squirrel lifespan is approximately 3 years, but some squirrels survive to 8 years of age. They can start reproducing in the year after they are born, or delay their first litter to 2 years of age or older. What happens in between varies significantly among individuals: some never succeed in producing a litter, while others breed in every year of their life, producing between one and fifteen pups in a given breeding season. Focusing on those females that successfully gave birth at least once, we determined the age at which they produced their highest number of pups, or their reproductive “peak”.

We then assessed whether females were able to match their reproductive peak to a mast year or not. This showed us that females were much more likely to achieve their personal high score in terms of pup production in a mast year if they were lucky enough to live through one – and for good reason. As we marked all pups individually soon after birth, we were able to then check which babies survived their first winter and thus reach maturity. This led us to discovered that when females matched their reproductive peak to a mast year, more of their pups survived to maturity. These females that maximized their breeding efforts in a mast year were less likely to survive long past that year, but her legacy would endure thanks to her genes that were passed along to the next generation of squirrels.

Most animals live in unstable habitats, in which breeding can be a gamble. Producing and raising offspring takes a lot of time and energy, and often reduces the lifespan of the parent when those resources are limited. An ability to interpret cues from the environment that allow the parent to anticipate opportunities available for their prospective offspring may change their reproductive “decisions” so that they forego breeding in one year, or give it everything they have in another year. In terms of evolution, this makes perfect sense: those individuals that solve this equation in the best way will contribute more to future generations, in a prime example of natural selection.

The average squirrel, like many other mammals, produces their highest number of offspring sometime in prime adulthood, with an increase in pup production in early life followed by declining performance at old age. There is vast variation in this age profile among individuals. It turns out that the timing as well as intensity of peak reproduction matters: females that can match their reproductive peak with favorable environmental conditions will produce more surviving offspring, and females that are able to produce more pups at their peak also contribute more squirrels in total to the next generation.

This youngster is receiving tags so that we can follow him through life. At this age, he is still being looked after by his mother, but in a few months’ time, he will have to leave home to find a vacant lot in the neighborhood and fill a pantry with cones that will get him through the winter. Photo by: Anni Hämäläinen.