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Wolf predation on deer fawns

Wolf V028 in Spring 2015.

Wolf V028 was one of the most proficient predators we have ever studied. The map below shows this well. Much of his proficiency was likely due to the fact that he was a prime age (6-7 yr old) wolf and the breeding male of the Moose River Pack, meaning he had to kill prey frequently for his pups to survive.

 

V028’s hunting abilities were far above the “average” wolf as most wolves in the population kill far fewer fawns than V028. For instance, we have studied several younger wolves that have only killed 2-6 fawns during the entire summer…and most wolf populations are comprised largely of young wolves like this.

Wolf V028 was one of the first wolves we studied in depth on our project. Since studying him, we have been fortunate to study the predation behavior of over 50 wolves, which has allowed us to understand many aspects of how wolves hunt and kill their prey.

Wolf V028's predation behavior over a 16 day period in late Spring 2016. This map shows all of V028's "clusters" of GPS-locations (i.e., areas where V028 remained relatively stationary for more than 20 minutes), represented by yellow dots. We have removed all of V028's travel locations between clusters to make it easier to see where V028 was spending time. We search each cluster of locations on the ground as these are all "potential kill sites". The large group of clusters in the middle of the map is the rendezvous site for the pack. One interesting thing to note is that V028 always made a kill before he returned to the rendezvous site, demonstrating that much of his predation behavior was motivated by feeding dependent pups.

In 2023, using data from V028 and many other wolves, we published a study that looked at where wolves hunt and kill deer fawns. We found that humans, through logging, the creation of roads and trails, and the development of infrastructure, have fundamentally reshaped where wolves hunt and kill deer fawns.

 

The premise of our major findings is really quite simple: human activities change where deer are on the landscape, and wolves go where the deer are. Plus, humans have done an excellent job of creating and maintaining a diverse, well-connected web of roads, trails, and other cleared linear features that are ideal corridors for wolves to hunt deer.

A composite image showing a wolf carrying a deer fawn down a logging road. This is the same wolf shown 4 different times as it runs down the road (i.e., this photograph is not of four different wolves).

Our objective was to understand where wolves hunt and kill deer fawns when fawns are young (<2 months old) and largely rely on hiding to avoid predators. This period is of interest because most wolf predation on fawns occurs during this period when fawns are young and vulnerable.

 

To do this, we searched areas collared wolves had spent >20 minutes in a 200 m area to identify where wolves killed fawns. In total, we found 427 wolf-killed fawns over a 6 year period.

 

We then examined where wolves hunted fawns by looking at where wolves traveled during the fawning season. Because fawns largely rely on hiding to avoid predators, the only way wolves can find fawns is by running around the woods trying to locate the hidden fawns.

Out in the field following wolves around to understand their summer behavior.

And thus, where wolves travel during this period is pretty much synonymous with where wolves hunt fawns, especially since the primary prey of wolves during this period are deer fawns. Using GPS-collared wolves, we identified 11,185 hunting locations during the fawning season.

 

We then examined what landscape characteristics had the largest influence on where kills occurred and where wolves hunted fawns. By and large, the most important and influential variables were all those associated with people.

A newly-born deer fawn

Specifically, we found:

 

1.) Wolves disproportionately hunted and killed deer fawns around recently logged areas — those logged within the past five years. This is likely because clear-cut forests provide dense stands of young saplings, supplying prime food for deer and excellent hiding spots for newborn fawns. Wolves seem to know these recently-logged areas are good hunting spots.

 

2.) Wolves killed deer fawns closer to human infrastructure, like cabins, year-round residences, and barns than would be expected. This is likely in part due to the fact that supplemental feeding of deer by people is common in the region, and this likely congregates deer near human-developed areas. The high concentration of deer near human development, in turn, attracts wolves to areas near people.

 

3.) Wolves preferentially hunted fawns from linear features — roads, ATV/UTV trails, power lines, and hunting lanes — and disproportionately killed fawns closer to these features than would be expected.

An area that has been logged recently with many visible roads and trails weaving through it. These are the kind of habitats that wolves use to hunt and kill deer fawns.

This was unsurprising as wolves face the same general issues that people do when traveling in the woods, and just like humans, wolves often prefer to travel on linear corridors than through dense forest. And these features make it easier to cover more ground more efficiently, and likely enhance wolves’ abilities to find vulnerable fawns.

 

Ok, so what does and doesn’t our research tell us?

A wolf carrying the remains of a deer fawn back to its pups.

Importantly, our research only looked at *where* wolves hunted and killed fawns. In doing so, it is clear people have influenced this aspect of wolf-deer relationships. However, what is not clear is whether or not human activities have actually increased wolf predation on deer. We did not look at rates of wolf predation (fawns killed per unit time) and thus our study cannot say whether people are actually influencing the number of fawns that wolves kill.

 

It is possible that human activities simply shift where deer are and thus while humans do impact where wolves hunt and kill deer, the same number of fawns might die regardless of whether there were or were not humans around. However, it is also possible that human activities have created a landscape that allows wolves to be more efficient predators than they would otherwise be.

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