Wild Pigs and Recreational Activities

Your ATV annoys the boar.

Is recreation and fun driving wild pigs off public land? One would tend to think so. Wildlife of any kind likes to stick to established routines and hold cherished siestas at appointed times of the day. What could be more unsettling than the sound of ATVs being recklessly forced into virgin territory?

Not much according to a study recently published in the Journal of Wildlife Management. Though the study referenced here does not include boar or wild pigs but rather concentrates on North American Elk, one can reasonably assume that the reaction of boar to the intrusion of noisy motor vehicles into their territory would have similar effects.

Knowing that ungulates are sensitive to human activities, the authors of this study measured the responses of elk fitted with motion sensitive radio collars from April to October in 2003 and 2004. The radio collars measured the reactions of thirteen female elk in five minute intervals recording resting, feeding and travel activities in relations to known disturbances of four types: ATV, hiking, mountain biking and horseback riding.

During the study times elk fed and rested without much traveling between activities. However, travel times increased during each of the disturbances. Travel was highest in the morning. It was also highest when exposed to ATV activities. Mountain biking and hiking ranked next while horseback riding caused the least disturbances. Overall feeding times decreased when ATV disturbance was present. Resting times also decreased but mainly in response to mountain biking and hiking.(Leslie M. Naylor, Michael J. Wisdom, Robert G. Anthony, Journal of Wildlife Management 2009 73 (3), 328-338 : Behavioral Responses of North American Elk to Recreational Activity)

The study clearly demonstrated the effect of recreational activities on elk. There is no reason that other large mammals would not be affected by human recreational activities correspondingly.

Human recreational activities are highest on public land where there is little effective control over ATV use and other forms of recreation. This is one of the reasons why wild pigs are very rare and mainly transitory on public land – as if we had not known this empirically all along.

But there are many others, such as shelter, cover and food. A decade ago researcher from the veterinary faculty of the University of Extramadura in Spain studied the effects of extreme weather conditions on the reproductive rate of boar. The study took place in the Donana National Park during extreme drought.

Researchers found births to be highly synchronized, mainly between February and April. The average litter size at an age of one week was 3.05 piglets per litter. This figure is much lower than normal litter sizes in Mediterranean boar populations. The percentage of breeding females was also much smaller than in comparable Mediterranean boar. It was below 17 percent.

The researchers conclude that female boar adjust their breeding decisions to drought conditions before the timing of breeding or litter sizes are changed. More drought, less breeding.(Fernandez-Llario, P; Carranza, J: Reproductive performance of the wild boar in a Mediterranean ecosystem under drought conditions; published in Ethology Ecology & Evolution [Ethol. Ecol. Evol.]. Vol. 12, no. 4, pp. 335-343. Dec 2000.)

An Austrian study by the Research Institute of Wildlife Ecology of the University of Vienna concludes that in poor habitat and environmental conditions strong hunting pressure on adult breeding females will have the greatest effect on population growth while under good conditions reducing the survival rate of juveniles is the most effective way to control expanding boar populations.

Nice and good, you say. That's over there. But we are here.

Well, ATV noise is disturbing regardless of which side of a border you are on. And drought is drought whether it strikes the Mediterranean or the western United States. The effects on wildlife are the same.

In one of my next posts we will have a look at fecundity, survival and pregnancy rates and other important family matters in boar and wild pigs.

PJJ