Bait delivery for oral rabies vaccine to gray foxes

Rabies is a widespread zoonotic disease that has reached epizootic proporti ons in gray foxes (Urocyon cinereoargenteus) in central Texas. Because each species of carnivore has different food preferences and foraging strategie s, it is essential that the efficacy of a bait delivery program be examined for gray foxes prior to an oral vaccination program being attempted. Field trials were conducted to determine bait preferences of free-ranging gray f oxes to selected baits and odor attractants. Baits consisted of polymer cub es made of either clog food meal or fish meal, and a wax-lard cake that was enhanced with marshmallow flavoring. Attractants added to baits exuded sul furous, fatty cheesy, or sweet odors and flavors. During 3,589 operable bai t station nights, gray fox visitation and bait uptake rates were 9.2% and 8 .3%, respectively. Gray foxes exhibited no preference in bait uptake rates between bait and odor attractant combinations. Gray foxes exhibited no diff erence in cumulative bait uptake rates between onroad and offroad sites; ho wever, the uptake rate by raccoons was significantly greater for baits plac ed on roads than for baits randomly placed. Raccoons were the major non-tar get species competing for baits, being attributed with 73% of the total upt ake. Visitation and bait uptake rates by raccoons significantly increased a fter a 7-day lethal removal of raccoons (n = 37) from the study area. Rando m distribution of baits is recommended; it reduced bait uptake by non-targe t species without adversely affecting uptake by gray foxes.