What IS over population?

By: Jeff Normandeau
Photos by Sarah and Jeff

http://sarah-and-jeff-normandeau.artistwebsites.com/

 

  I'm a professional wildlife conservation technician (Jeff ) who has worked for a number of organizations. Deer over population is actually a research area I have taken part in before, What I know is mostly from a Canadian perspective, but generally the same issues exist in the US particularly the Eastern US.

First, over population of deer is a completely subjective term, it means completely different things to an ecologist, a farmer, a hunter and society as a whole.

To a hunter as long as the deer population doesn’t drop so much that their tags won’t be reduced, they will call the deer over populated. After all, their only concern is to get to go out and enjoy their hobby.

To a farmer, their concern is how much damage deer do to their fields. If they start to have measurable losses in the revenue from their crops, then deer are over populated. Hunting to a farmer is generally a cheaper solution then other deterrents (even though it’s temporary)

To society, deer are over populated generally when car accidents rates rise too much. Again hunting tends to be the cheaper solution then other deterrents to keep deer off roads.

To an ecologist, deer are over populated when/if they begin to outstrip the resources of their habitat for a prolonged period of time and actually begin to harm the habitat/ecosystem. In reality, this is a very rare scenario. Deer, like many animals follow a boom and bust cycle. Populations grow until there are too many deer for the habitat. As they outstrip the resources, the weaker animals can not compete, the deer population then decreases until the balance swings the other way, resources become over abundant again and the deer population will rise. Predators will follow a similar cycle (slightly delayed and balanced by the other species they eat), predators populations will increase while deer populations increase, then as deer populations crash predators will crash as well. Natural mortality factors will keep the deer population from increasing/crashing too fast. These are things like predation, and winter starvation.

Deer becoming over populated in an ecological sense is very rare, because the populations naturally correct themselves. The only example I have ever heard of true over population was at a national park where I worked. Some of the park property was on an island, the interior of the island was all park property, the water front was all privately owned cottages. All the predators on the island had been hunted to extirpation before it was donated to the park. The owners of the cottages liked the deer so they would feed them, this meant that deer would not die due to predation or starvation. Old age/illness became the only mortality factors and the deer continued to strip the habitat of all vegetation year after year without a population crash. In this situation a cull was determined to be the only cost effective solution. But it’s important to note that it only came about because of human interference. If people didn’t feed deer and didn’t hunt the predators, there never would have been a problem. Predator hunting is a huge issue in the Eastern US, as the eastern cougar is practically non existent now, and wolf and black bear populations only remain in a few states.

I once had a conversation with a biologist who was responsible for setting the hunting limits for deer in a part of Ontario. He basically said the goal when setting hunting limits was to keep them right at the middle of the boom/bust cycle, a safe distance from a population crash, but don’t let them start to strip resources. He said hunting played an important role in avoiding the boom/bust cycle. After he said this, I asked him why, when so many animals follow a boom/bust cycle, do we find it important to hunt deer to prevent this cycle?

His answer was “because we hunt deer”. He elaborated his point saying, that because we hunt deer, we have to manage their population, because we are hunting and managing their population, hunting becomes an important management tool. So we need to hunt deer because we hunt deer. If we didn’t hunt deer we wouldn’t need to hunt deer.

So the next time a hunter tells you people have to hunt because deer are over populated you can tell them, deer are only over populated because you hunt. This conversation becomes even more cyclical when the hunted species is coyote. Coyotes actually breed more if a pack member is killed, so a hunter who thinks there is a coyote over population problem is actually causing population increases by hunting coyotes. Not too mention coyote population growth was initially caused by over hunting of wolves, leaving a vacuum at the top of the food chain. So, leave nature alone and it will balance itself.