Electronic Thesis and Dissertation Repository

Thesis Format

Integrated Article

Degree

Master of Science

Program

Geography

Supervisor

Long, Jed

2nd Supervisor

Wang, Jinfei

Abstract

The social structure of invasive wild pigs directly affects the risk of disease transmission and other harmful effects. Here, the social structure of wild pigs at four study sites in the United States was measured between individuals and within dyads over time to gain insight into contact heterogeneity and the cohesiveness of social groups using GPS tracking data. A data stream randomization test was used to identify pairwise social associations based on synchronous movement, and contact patterns within social pairs were measured over time. Wild pigs at all four study sites exhibited contact heterogeneity, but more moderate association rates were observed in social pairs as well. It was found that most social pairs had long interruptions in their associations over time characterized by less cohesive movement and space use. Therefore, periods of non-social behaviour and space use should be accounted for within wild pig social groups.

Summary for Lay Audience

Wild pigs are a widespread invasive species in the United States, responsible for $1.5 billion USD in damages to crops, livestock, wildlife and the environment every year. Female wild pigs live in packs and primarily interact with other pack members, but little is known about how much pack members interact with each other, or how interaction patterns between individuals in packs might change over time. Interactions between wild pigs affect the risk of disease transmission and other harmful damages, making the relationship between pack membership and patterns of interaction an important research topic. To study this relationship, GPS tracking collars were used to measure interactions between wild pigs at four study sites in the southeastern United States. First, packs of wild pigs were identified using the GPS tracking data by measuring how interactions depended on synchronized movement. Next, interactions between individuals belonging to the same pack were measured over time to look for patterns in how often pack members interacted or did not interact with each other. Multiple unique packs of wild pigs were found at all four study sites, but not all packs had the same amount of interaction between pack members. It was found that wild pig pack members went long periods without interacting with other pack members, indicating wild pig packs are not always together. The implications of these findings are that the amount of interaction that constitutes belonging to the same pack as another is not equal across all wild pig packs, and even though wild pigs live in packs, they can temporarily leave their pack. This is important knowledge for managing wild pigs because the splitting of packs could lead to disease transmission and other harmful behaviours. More generally, this research provides a more detailed understanding of wild pig pack structure and the relationship between pack members.

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