Reproduction of wild boar in a cropland and coastal wetland area: implications for management

Abstract

The reproductive parameters of a wild boar population located in a coastal landscape with a mosaic of cropland and wetland habitats were analysed and compared with those observed in wild boar populations living in other habitats. A total of 296 reproductive tracts of females captured year round at the Aiguamolls de l’Empordà Natural Park were collected and analysed from 2000 to 2010. The foetuses were counted, sexed and aged and the mating and birth periods were determined. The weight and age of each female were also recorded. In accordance with the pattern observed in most European populations, a marked main mating season from October to January was observed. Within this season, there was a peak during November and December, in which 64% of the conception dates were recorded. The proportion of breeding females, ovulation rate and litter size increased with the weight of the reproductive females. A mean litter size of 5.01 ± 1.33 (range from two to eight) foetuses was recorded. This value is the highest known litter size recorded in wild Iberian populations and is similar to values observed in central Europe. Furthermore, it is not in accordance with the pattern reported for other European populations in which a positive correlation between litter size and latitude was observed. The most likely explanation for the high reproductive output in the study area is the availability of food year round, and especially the high consumption of crops such as maize and sunflower. Our results suggest that colonisation of cropland and wetland areas is contributing to the rise in the wild boar population density. Control strategies should consider not only reducing numbers of adult females but also applying measures to reduce food resources available to wild boar.