Ask The Biologist

Bear Pit

Bear Pit

By Bob Humphrey

Maine’s deer numbers are low, and predators could be part of the problem.

QUESTION: We have a lot of bears where I live in Maine, and the state is trying to figure out how to get hunters to shoot more. We also used to have a lot more deer. I’m wondering if the bears might be eating more deer now that there are more of them. How common is it for bears to predate deer? – Nate B.

ANSWER: There have been several studies done on bear predation of deer, most notably a Penn State study that showed bears to be a significant predator of fawns. It would not be unreasonable to assume higher predation rates where there are more bears.

However, nature has a way of balancing things out. Prey species like deer rely on a phenomenon known as predator swamping. Most does give birth around the same time. Predators are limited as to how many fawns they can find and kill in a given time period, and having so many fawns available to predators during a relatively short time increases the chances of survival for each fawn.

The situation becomes more problematic in areas with high predator densities and low prey densities. Then, predators can remove a higher proportion of prey, sometimes to the point where the prey population cannot compensate for losses.

This situation is known as a predator pit or predator sink. In more classic predator-prey relationships like mink and muskrat, lynx and snowshoe hare and grouse and goshawks, predator populations will decline as prey abundance declines. Because bears are omnivores and are not dependent on fawns for food, however, a decline in deer will not result in lower bear numbers.

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Copyright 2020 by Buckmasters, Ltd.

Copyright 2020 by Buckmasters, Ltd