Characteristics of wild pig farrowing nests and beds in the upper Coastal Plain of South Carolina

Abstract Thirteen farrowing nests and nine resting/loafing beds built by wild pigs ( Sus scrofa ) from an introduced population in South Carolina, USA, were studied with respect to physical description, size parameters, the animals involved, and adjacent surroundings. The nests, built by pre-parturition sows, were generally round to oval shaped, with the length and width being positively correlated. Larger sows built significantly longer and higher nests than their smaller counterparts. All nests were located in excavated depressions. Six of the nests were built next to trees, uprooted stumps, or logs, and all but one were lined with vegetation as a nesting material. Nesting materials varied, but consisted of plant species that were readily available and gathered from within 20 m of the nests. Larger, older sows traveled significantly further to collect these materials for their nests than did smaller, younger sows. All nests were located under protective overhead cover, and most were located in forested areas with a generally open understory. The nests with the highest amounts of nesting materials were built in the youngest forests. This study was the first to show variation in nest parameters in relation to the age/size of the sow, and in relation to the surrounding environment. Based on the characteristics of the farrowing nests analyzed in this study, it would appear that their function is probably more one of protection from inclement weather rather than from visual predators. The 13 farrowing nests were then compared to the nine resting/loafing beds. Beds built and used by solitary animals were similar to the farrowing nests, but were comparatively smaller in relation to the size of the animals involved. In addition, some of the solitary beds were neither excavated nor lined with material. However, common characteristics shared between nests and solitary beds make it difficult to distinguish between these two types of structures built by wild pigs.