A field evaluation of baits for delivering oral rabies vaccines to raccoons (Procyon lotor).

Eight field trials were conducted in 1989 and 1990 in Georgia (USA) and Maryland (USA) to evaluate baits and baiting strategies for delivering oral rabies vaccines to raccoons (Procyon lotor). Bait packets consisting of corn meal and egg batter-based baits enclosed in plastic bags were placed at 1.0-m diameter, raked tracking stations and checked daily. Packets were well accepted by raccoons; they visited 31 to 44% of the tracking stations where they removed 69 to 90% of the packets within 4 to 5 days. All or nearly all baits were removed from plastic bags and less than 1% of the baits were found only partially eaten. No rejection of water-filled paraffin ampules in baits was observed. The use of an odor attractant on bait packets did not appear to enhance bait discovery when packets were placed on raccoon travel routes. An attractant did enhance discovery when baits were placed off-road in a simulated aerial baiting test. Nontarget species comprised 31 to 53% of all visits to the stations; they took 28 to 55% of the baits but did not appear to adversely affect bait availability for raccoons. A total of 2,300 baits, each containing a wax ampule holding 10 mg of a physiological marker (iophenoxic acid), were distributed at a rate of 82 baits/km2 on 2,800 ha of Sapelo Island, Georgia. Thirty-five (65%) of 54 raccoons collected following bait placement had eaten one or more baits as indicated by elevated levels of iodine in the blood serum.