A Preliminary Field Trial of Bait Stations for the Delivery of Oral Rabies Vaccine: Can Varying Diameter Exclude Non-Target Species?

Abstract

Delivery of oral rabies vaccine can be an effective method for combating rabies, but broadcasting vaccine sachets over wide areas creates the potential for non-target species to ingest vaccine baits before the target species encounters them. An alternative is to present the vaccine at a bait station designed to allow access by target species, while excluding some non-target species. We tested whether bait stations constructed of PVC pipe of 3 different diameters (10, 15, and 20 cm) differed in their effectiveness in allowing access by striped skunks versus other, non-target, nocturnal mammals in the urban environment of Flagstaff, Arizona. We placed bait stations in sets of 3 at 13 locations during late February and early March 2005 and monitored their use for 5 nights using digital still cameras. We recorded visits by striped skunks, gray foxes, raccoons, and domestic cats and dogs. Large-diameter tubes were used by all species, though large dogs had limited access, and small-diameter tubes were entered only once (by a skunk). Medium-diameter stations were used by all species except dogs, but skunks entered these stations more readily (81% vs. 44% or less), indicating that baits in 15-cm tubes would be more readily accessed by skunks. If striped skunks are the primary target species, we recommend the use of medium-diameter bait stations, as these stations excluded all dogs and reduced bait uptake by cats, foxes, and raccoons. If foxes and raccoons are also targeted, large-diameter stations will be required, and these will be available to all cats and some small dogs but should exclude larger dogs. Given the cost of this type of bait station in both time and money, we recommend their use only in limited areas where potential interaction with non-target species is of special concern. However, when one considers the value of human life, the cost may be negligible.