Size and Composition as a Proxy for Identification of Wild Pig Sounders

Abstract

Management of wild pigs (Sus scrofa) typically employs some form of population survey methodology, and trail cameras are the most common tool for conducting these surveys. Identification of individual sounders is generally at the foundation of these population surveys. Pelage characteristics and relative age distribution of individuals within the sounder coupled with total sounder size are common characteristics used to identify unique sounders. However, in many populations, the pelage of many wild pigs is either black or wild/grizzled, making pelage characteristics unreliable for sounder identification. Consequently, our objective was to assess the potential of using sounder size and composition as a simple proxy for identification of individual sounders visiting a camera station. Specifically, we aimed to determine the probabilities of encountering two sounders of a specific size and composition at the same camera site. Our findings revealed that sounders comprised of two adult wild pigs were the most common to be found at the same camera site. Yet, sounders of unique size and composition with more than three adults had a very low frequency (<3.6%), and frequency showed a tendency to decrease as sounder size increased. Our data indicate that most sounder size/composition categories (88.8%) can be identified individually with high (>95%) confidence simply by counting the number of individuals and number of adults in the sounder. Only four sounder size/composition categories (sounder of two with zero adults, sounder of two with two adults, sounder of three with zero adults, and sounder of three with one adult) had probability of co-occurrence >0.10. Hence, our study suggests that using sounder size and composition as a proxy for sounder identification is suitable for population surveys and management purposes.