"Wolves encounter unique hunting challenges during the winter as snow increases the cost of locomotion and influences their ability to detect and pursue prey"..........."During the two winters of 2013-14, University of Alberta(Canada ) researchers investigated the effects of snowfall events on grey wolves in the boreal forest ecosystem of northeastern Alberta............"They found that wolves were less likely to travel on dates of snowfall events than any date prior to or after an event".............."Wolves also traveled more slowly during snowfall, but only when compared to their travel speed 24 hours before"............."Effects were most pronounced at night, when movements appeared to be consistent with hunting behavior"..........."Activity levels resumed within 24 hours of a snowfall ending".........."The Scientists conclude that wolves reduce their activity levels because precipitation dampens hunting success as their ability to detect prey(combined with changes in prey activity behaviour) dampen encounters and subsequent kill success"

https://phys.org/news/2018-12-wolves.html

Snowed in: Wolves stay put when it's snowing, study shows

December 19, 2018 by Katie Willis; University of Alberta, Canada

Wolf tracks across snow in northeastern Alberta. The study found that wolves travel shorter distances and move slower during snowfall. Credit: Amanda Droghini

Wolves travel shorter distances and move slower during snowfall events, according to new research by University of Alberta biologists. The effects were most pronounced at night, when wolves hunt, and behaviour returned to normal within a day. Wolf tracks across snow in northeastern Alberta.

"Our findings suggest that there is something about actively falling snow that causes wolves to slow down," said Amanda Droghini, a former MSc student in the Department of Biological Science and lead author on the study. "We don't know the exact mechanism behind that. It's unlikely that they were staying still because they were feasting on a recent kill. Instead, active precipitation might affect wolves' hunting abilities. Like rain, snow clears the air column of scent molecules. So, maybe falling snow makes it harder for wolves to detect the smell of prey."

In their study, researchers used cameras and data transmitted from collars on 17 wolves. (Submitted by Amanda Droghini)

Over the course of two winters, the researchers used remote cameras to identify snowfall events and estimate snow depth. To study wolf movement, they collected telemetry data from 17 wolves to calculate travel speed and duration, as well as resting periods. It is the first study to examine how large carnivores respond to snowfall events.

With the effects of climate change on precipitation in the boreal forest region uncertain, it is difficult to predict the implications for wolf populations. Studies such as these increase our understanding of how large mammals react to normal snowfall events, but the type and amount of winter precipitation will likely have an impact on animal behavior and the energetic cost of movement.

Site of the Study--Alberta on the Canadian map

Map of our study area in northeastern Alberta, Canada, near the town of Fort McMurray.

From January to March 2013 and 2014, remote cameras were deployed to identify snowfall events, and 17 grey wolves were equipped with GPS telemetry collars. Location fixes were acquired every 10 or 30 minutes and are summarized here as daily centroid locations. Each color represents a wolf pack (n = 9, plus one lone wolf). Major rivers are shown in dark blue, while linear features (mostly seismic lines for oil and gas exploration) are in grey.

"Winter is already challenging for many wildlife species because moving through snow requires more energy. Snow can also make it harder for animals to access food resources," said Droghini, who conducted the research under the supervision of Professor Stan Boutin, Alberta Biodiversity Conservation Chair.

"Anything that increases those costs, such as increased rain-on-snow events, could lead to nutritional deficiencies, poor body condition, and even starvation as animals are unable to make up for those additional costs. That is one of the worst-case scenarios but, in truth, we know very little about potential changes to precipitation patterns and how wildlife will respond to those changes."

The paper, "The calm during the storm: Snowfall events decrease the movement rates of grey wolves (Canis lupus)," was published in PLOS One.

More information: Amanda Droghini et al, The calm during the storm: Snowfall events decrease the movement rates of grey wolves (Canis lupus), PLOS ONE (2018). DOI: 10.1371/journal.pone.0205742 

Journal reference: PLoS ONE