Seasonal variation in space use and territoriality in a large mammal (Sus scrofa)

Peter E Schlichting,Wes Anderson,Ryan S Miller,Raoul K Boughton,Bethany Wight,Jesse S Lewis,Kurt C Vercauteren

doi:10.1038/s41598-022-07297-y

Abstract

An individual’s spatial behavior is shaped by social and environmental factors and provides critical information about population processes to inform conservation and management actions. Heterogeneity in spatial overlap among conspecifics can be evaluated using estimates of home ranges and core areas and used to understand factors influencing space use and territoriality. To understand and test predictions about spatial behavior in an invasive large mammal, the wild pig (Sus scrofa), we examined variation in space use between sexes and seasons. We predicted that if animals were territorial that there would be a reduction in space-use overlap when comparing overlap of home ranges (HR–HR), to home ranges and core areas (HR–CA), and in-turn between core areas (CA–CA). Home ranges and core areas were estimated for 54 wild pigs at Buck Island Ranch, FL from GPS telemetry data. Overlap indices were calculated to estimate the strength (space-use overlap) and number of potential interactions within three wet seasons (June–October) and two dry seasons (December–April). Among sexes, home range size did not vary seasonally, and males exhibited larger home ranges compared to females (M = 10.36 ± 0.79 km2 (± SE), F = 3.21 ± 0.16 km2). Strength of overlap varied by season with wild pig home ranges overlapping more during the dry season. Males interacted with a greater number of individuals of both sexes, compared to females, and exhibited greater strength of overlap during the dry season. Consistent with our predictions, wild pigs appeared to exhibit territorial behavior, where strength of overlap decreased when comparing HR–HR to HR–CA and HR–CA to CA–CA. Our framework can be used to understand patterns of space use and territoriality in populations, which has important implications in understanding intraspecific interactions and population processes, such as how pathogens and parasites might spread within and among populations.

Highlights

Variation in spatial interactions among animals can identify the selective pressures that shape spatial behavior
Non-territorial species are expected to overlap with conspecifics at random which would result in overlap with a similar number of individuals in home ranges and core areas (Fig. 1)
It is predicted that if animals are territorial that there will be a reduction in spatial overlap when comparing overlap of home ranges (HR–HR), home ranges and core areas (HR–CA), and core areas (CA–CA) (Fig. 1)

Summary

Introduction

Variation in spatial interactions among animals can identify the selective pressures that shape spatial behavior. Non-territorial species are expected to overlap with conspecifics at random which would result in overlap with a similar number of individuals in home ranges and core areas (Fig. 1). Territorial behavior creates spatial heterogeneity in the number and strength of conspecific interactions, leading to reduced overlap of core areas compared to home ranges (Fig. 1). Female groups are argued to be territorial with other female groups where groups overlap in their home ranges, but exhibit mutually exclusive core areas[27,45,46] This pattern, is not detected in other systems[35,47,48] and the role of territoriality in wild pig social structure is unclear. Spatial overlap, and territoriality vary across seasons has not been widely evaluated for wild pigs and it is unclear how different behavioral and environmental factors influence space-use overlap. Our third objective was to use measures of spatial overlap to evaluate territoriality of home ranges and core areas and how overlap varied

Methods

Results

Conclusion