Wolves eating berries
We have learned a lot about wolves foraging on berries since we first learned of the behavior by studying Wolf V026 in 2015. In fact, most wolves we have studied since then have spent a substantial amount of time eating berries (primarily blueberries with some raspberries on the side) during July and August.
This behavior is extremely easy to identify from the GPS-location data as you can see in the maps below. Basically, the wolves just go to berry patches and wander around eating berries, returning over and over to the same patch. Berry patches in our area are either spread across rock ridges or boggy environments, especially those that have been logged in the not too distant past.
GPS-locations from a collared wolf in Summer 2023. The blue outline shows where the berry patch was and the dots are GPS-locations from the collared wolf.
These kinds of habitats are quite abundant in our area and so it is no problem for wolves to find lots of good berry patches and move around between them. Anyway, we visit all these berry patches that collared wolves are foraging in to verify the wolves did not kill prey in those areas. And all we ever find are wolf scats loaded with berries.
Now, it is easy to think wolves are just eating the berries because they are nutritious. However, berries are almost certainly "starvation food" for wolves; as in, the wolves are starving and berries are the best option given the circumstances to stave off hunger and slow weight loss. While no one has ever fed wolves a strict fruit diet to see what happens (that we are aware of), one study on wild red foxes in Quebec was revealing.
GPS-locations from a collared wolf in Summer 2023. The white outline shows where the berry patch was and the dots are GPS-locations from the collared wolf.
The researchers fed one group of wild foxes diets largely composed of fruits and then another group of foxes a normal meat diet. The researchers found that the foxes on a fruit diet lost body fat and protein whereas the other foxes did not.
Their conclusions: "Consuming a high proportion of fruits may lead to faster satiation (because of extra volume) and faster passage through the gastrointestinal tract. Thus, carnivores feeding on fruits must feed more often for shorter periods, and are likely to gain less energy than when feeding on animal prey. We conclude that high fruit consumption...likely indicates shortage of animal prey for free-ranging red foxes, and probably for other canids, such as coyotes”.
And we would add wolves here too!
An adult wolf foraging on berries.
All evidence indicates wolves are not eating berries instead of other animals because they prefer berries over meat. We have no doubt that if a wolf had an option between a meal of berries or of deer/beaver that it would choose the latter every single time.
Catching deer and beavers is extremely challenging for wolves in late summer, and likely requires extensive energy expenditure. Thus, instead of spending substantial energy hunting prey they likely cannot catch, wolves turn to berries, which are abundant, taste good, and likely make them feel full.
A wolf and her pup foraging for berries together in Summer 2022.