Assessing the Potential of Camera Traps in Monitoring Wild Boar Occupancy Trends in Infected and Noninfected Zones, Using Spatio-temporal Statistical Models

• Activity Number: 322 - Analyses in Ecology, Epidemiology, and Environmental Policy
• Type: Contributed
• Date/Time: Wednesday, August 11, 2021 : 3:30 PM to 5:20 PM
• Sponsor: Section on Statistics and the Environment
• Author(s): Martijn Bollen* and Natalie Beenaerts and Thomas Neyens and Jim Casaer and Maxime Fajgenblat and Valérie De Waele and Alain Licoppe and Benoît Manet
• Companies: UHasselt - Research Institute for Nature and Forest and UHasselt and UHasselt - KU Leuven and Research Institute for Nature and Forest (INBO) and KU Leuven and Service public de Wallonie and Service public de Wallonie and Public Service of Wallonia
• Keywords: African swine fever; Camera traps; Occupancy; Spatio-temporal; Bayesian inference; Stan

Abstract

African swine fever (ASF), a viral disease causing high mortalities in suids, has recently been reintroduced to the Eurasian continent. Free ranging wild boar (Sus scrofa) have been recognized to play a key role in the spreading of ASF. Hence, updated information on wild boar population trends and impact of ASF as well as ASF control measures thereon are crucial. As such, we use absence-presence data (March 2019 – May 2020), obtained from a camera trapping network in the South of Belgium, to compare joint effects of ASF and culling efforts on wild boar population trends between infected and noninfected areas. We fit a spatio-temporal zero-inflation model that accounts for false absences using Hamiltonian Monte Carlo estimation, and attempt to capture extra-variability by the addition of a spatial Gaussian process. Our model successfully captures significant population declines and attributes differences in initial occupancy to the infection status. Over a period of 15 months, we find mean extinction rates between 22.44% and 91.35%, depending on the infection status. Together, these results confirm the effectiveness of ASF control measures implemented in Belgium.