Reproductive and demographic parameters in two Iberian wild boarSus scrofa populations

Abstract

From 1990 to 2006, we studied the demographic, reproductive, and biometric characteristics of two Iberian wild boarSus scrofa (Linnaeus, 1758) populations in contrasting environments. In the Pyrenees (studied in 1990–1993), forest cover is high, hunting pressure is low, and the density of wild boar is high. In the Ebro Valley (studied in 1994–2006), there are few shelter areas for boars, hunting pressure is high, and density is very low. In the second semester of life and after two years of age, the sows in Ebro Valley were heavier than were those in the Pyrenees. Pregnancy during the first year of life was frequent in the Ebro Valley and rare in the Pyrenees. Litter sizes, ovulation rates, and intrauterine mortalities did not differ significantly between the two populations, but the foetal sex ratio in the Ebro Valley was skewed significantly towards males. Life expectancy was lower in the Ebro Valley (6 yr) than it was in the Pyrenees (10 yr). In the Ebro Valley 75% of the wild boar were >24 months old, whereas in the Pyrenees, the proportion was 59%. We suggest that shelter availability influenced the growth, productivity, hunting pressure, and life expectancy in the two Iberian populations of wild boar.