by Whit Gibbons

August 6, 2017

The following questions represent a common theme this time of the year.

Q: This summer my daughters and I have had many more encounters with snakes around our house than usual. Even though some are copperheads, I still don't want to kill them. I know it's hard to deter snakes, but is there any good method of enticing them back into the woods?

A: Luring snakes from one area to another is not feasible. But if a snake arrives at a site that it finds more habitable than the area it left, it is more likely to stay. The opposite, of course, is also true – a snake is less likely to stay in an area it does not perceive to be suitable habitat. Generally, ground coverings such as leaves, pine straw, lawn trimmings, brush, logs, boards, shingles, roofing tin or low vegetation offer hiding places where snakes can find protection from predators. These would also be places where they are more likely to find prey. So your first step would be to ensure that neither snakes nor what they eat have a hiding place around your house – or wherever else you don’t want the snakes.

Physically removing snakes from one area and relocating them to another is problematic. Large species may return to their home range, often over long distances. Some species of animals have been known to return to a site from where they were removed though it was many miles away. Ecologists have not determined precisely how they find their way back.

Q: We used to see rabbits in our neighborhood but not this year. Where have they gone?

A: Fluctuations in animal numbers from year to year are a universal phenomenon. The numbers observed may vary greatly across years and geographic regions. Population sizes typically oscillate for most animals, especially in response to the balance between predators and prey in a given area. Unless an unnatural problem such as pollution or pesticides persists, numbers will eventually return to what has been more commonly observed. But population sizes of most species will continue to fluctuate from year to year.

Sometimes, animal abundance or rarity is more perception than reality since observations of wild animals are generally chance encounters. I once received a question from someone about why so few blue jays were in the area that year, as they had once been common. A week later I got a query from someone in the same town asking why so many blue jays were present that year. I’ve had contrasting queries from folks about common animals such as squirrels, butterflies and ladybugs, as well as less frequently seen animals like bobcats, bears and screech owls. Sometimes they seem common and other times rare.

Fur trapping records for lynx (the northern equivalent of bobcats) and snowshoe hares during the 1800s revealed a recognizable wildlife cycle of approximately 10 years. One conclusion by wildlife biologists was that hares are a staple in the diet of lynx, and snowshoe hare numbers decline precipitously because lynx eat them, thus reducing the size of the hare population. The simplistic explanation followed that as the lynx’s target prey species is no longer abundant, lynx populations begin to decline because of lower reproduction rates and possibly even starvation. This, in turn, leads to an increase in hare population size because the lynx predator is no longer common enough to control the number of hares. Thus the cycle continues.

Change in the abundance of any animal species at a given location over time is a natural phenomenon. Almost everywhere, some species will be more abundant than in previous years whereas others will be on the decline or even absent entirely. These so-called wildlife cycles are not just perceptions; they are real. But they are not necessarily predictable or consistent. And what exactly causes them has puzzled and intrigued fur trappers, farmers and ecologists for more than two centuries.

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