Selective piglet feeders improve age-related bait specificity and uptake rate in overabundant Eurasian wild boar populations

Abstract

The Eurasian wild boar (Sus scrofa) is a reservoir for pathogens that affect both humans and domestic animals. The control of these diseases requires the development of strategies such as oral vaccination of the reservoir species. The aim of the present study was to determine the species-specific visitation and removal rates of cereal-based baits under field conditions in an overabundant wild boar population. Two different field trials were conducted at a hunting estate. In one trial, baits were placed at track stations set up either randomly in the undeveloped portions of the estate or close to permanent wild boar feeding places. In the second trial, baits were placed in feeders that were selective for use by wild boar piglets. Both trials were conducted in summer 2007 and repeated in spring 2008. No evidence of attractant effect by the bait was found when comparing baited against control stations. A close proximity to the feeders was associated with an increased probability of being visited by wild boar, and piglet feeders were shown to be highly selective for young wild boar. Baits disappeared faster in summer than in spring (i.e.~70% consumption after the first day in selective feeders in summer, and 40% in spring). Therefore, a combination of a summer season and selective feeders was found to be a potentially reliable bait-deployment strategy for wild boar juveniles under Mediterranean conditions. These results support the use of selective feeders for oral delivery of baits to 2-4-month-old wild boar piglets, which is the preferred age for vaccination. Our delivery technique based on selective piglet feeders also has potential for other uses in the Eurasian wild boar and wild pigs under different management conditions.

Specificity and success of oral-bait delivery to Eurasian wild boar in Mediterranean woodland habitats

“…Inside selective feeders, young wild boar were more frequently detected than adult wild boar. This result confirms the efficacy of selective feeders to deliver baits to young wild boar (Ballesteros et al 2009a). Birds, highly abundant inside feeders in site 1, have been demonstrated to have no effects on the integrity and persistence of baits (Ballesteros et al 2009a), which was also confirmed in the present study.…”

“…This result confirms the efficacy of selective feeders to deliver baits to young wild boar (Ballesteros et al 2009a). Birds, highly abundant inside feeders in site 1, have been demonstrated to have no effects on the integrity and persistence of baits (Ballesteros et al 2009a), which was also confirmed in the present study. Outside feeders, a wider range of species was detected, being the wild boar (both adult and young) and red deer the most frequently found in accordance with the distribution and abundance of both species ( Fig.…”

“…It is almost impossible to avoid badgers entering the feeders. However, apparently, badgers do not chew these capsules as efficiently as wild boar do (Ballesteros et al 2009a) so it is unlikely that badgers could have contact with the vaccine. These results confirmed the selectivity of the delivery methods for wild boar, although badgers could interfere locally with the wild boar bait uptake rate.…”

“…Sites 1 and 4 were pre-baited for 5 weeks, and sites 2 and 3 were pre-baited for 3 weeks. Every 3 days, we checked them to record feed consumption and pictures were examined to determine if young wild boar entered the feeders (Ballesteros et al 2009a) and if adult ones turned the stones (unpublished observations). The fact that adult wild boar turned the stones did not mean that they consumed all the baits below them since other animals like young wild boar could gain access to the baits after adult ones turned the stones.…”

“…In Spain, controlled vaccination trials are being conducted to eventually use wildlife vaccination as a disease management tool for Aujeszky's disease and bTB (Ballesteros et al 2009c). Additionally, we developed oral baits suitable to deliver pharmaceuticals to free-living wild boar, and developed techniques to improve specificity and uptake rate in overabundant wild boar populations (Ballesteros et al 2009a). These baits could be used for the oral immunization of 2-4-month-old wild boar piglets (Ballesteros et al 2009b).…”