Boars Everywhere: Climate Change is Boosting Wild Pig Populations

When wildlife experts discuss climate change, they usually are talking about the worrying decline of one species or another. This, however, isn't the case for European wild boars. New research has found that these pigs have enjoyed significant population growth starting more than three decades ago, and they have a warming world to thank for it.

That's at least according to a study recently published in the journal PLOS One which details how wild boars (Sus scrofa) have been gaining ground across Europe since the early 1980s.

According to wildlife biologist and first author of the study Sebastian Vetter "it is not so easy to determine the number of wild boars in Europe." That's largely because the quick and skittish animals usually frequent dense and overgrown forests where beechnuts and acorns, hearty staples of their diet, can be found.

However, in the recent decades, more and more boars have wound up as road kill and in hunting bags - a strong indication that local populations are growing and gaining ground. (Scroll to read on...)

To find out what's going on here, Vetter and his colleagues collected boar population estimates from twelve European countries. These records were then compared with temperature and precipitation data, with some information reach back to 150 years ago in some regions. They identified a clear trend.

"There is a sharp increase in the number of wild boars after mild winters," Vetter said in a recent statement.

According to the researcher, this is primarily due to the fact that these wild pigs burn a great deal of energy to stay warm. After long and cold winters, surviving boars have less stored energy available for production and the rearing of offspring. Like with many mammals, harsh winters also cull the weakest young. This is why Vetter and his team suspect that climate change, with its warming net temperatures, is having an impact on how many piglets survive.

"As mild winters are becoming more frequent, also wild boar populations are growing exponentially," he said. (Scroll to read on...)

However, the investigators are careful to add that it's not just warmer winters that the boars should be thankful for.

Experts have long known that boar populations briefly spike in the wake of mast years - when trees bear a larger haul of nuts than usual. According to past surveys, these mast years used to be far and few between; however, experts have determined that in the last couple decades, these irregular mast years have become increasingly frequent, potentially because of warmer summers. What this means for boars is more energy to go around, helping them even through harsher winters.

The climate of these key winters and summers may even have a lasting impact on the size of boars in any one area. In fact, in a warming world, Europe may begin to see a lot more tiny porkers running around.

"Wild boars in the south are smaller than those in the north," Vetter added. "Being small is unfavorable in the cold but thermoregulatory beneficial during hot summers. Regionally differing body size of wild boar is the reason why population growth began virtually simultaneously throughout Europe, despite considerable differences in winter temperatures."

And while this may be some welcome news for hunters looking to bag some bacon, it's pretty bad news for farmers. Trapping and crop security has become more and more essential in fields that are regularly raided by these pillaging porcine. Thus Vetter and his colleagues argue that keeping tabs on wild boar populations will prove paramount to wildlife and resource management in the years to come.

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