Responses of captive and free-ranging coyotes to simulated oral rabies vaccine baits.

Abstract

The objective of this study was to develop a bait for delivering an oral rabies vaccine to free-ranging coyotes (Canis latrans) in southern Texas. Captive trials were conducted from January to April, 1994, to determine bait preferences and behavioral responses of coyotes (n = 42) to selected baits and attractants. Baits were hollow rectangular cubes made of polymer dog food or fish meal. Attractants had sweet (watermelon), fruity (raspberry), sulfurous (synthetic WU), and lard (beef lard) fragrances. Captive coyotes did not exhibit a preference for either bait bases or attractants; however, coyotes chewed dog food baits 1.6 times more than fish meal baits. Average proximity of coyotes eliciting a response to baits was 2.2 +/- 1.3 m (mean +/- SE). Captive coyotes readily accepted dog food baits containing 2 ml of liquid rhodamine B, a biological marker. Rhodamine B staining of the oropharyngeal region was evident in each captive coyote. Results from the field evaluation of baits and attractants were consistent with that of the captive trials. Of 2,070 bait station-nights conducted from February to April, 1994, coyotes comprised the greatest single species visitation and uptake rates with 31% and 28%, respectively. Bait uptake rates of free-ranging coyotes did not differ among bait-attractant combinations. Coyotes took baits 93% of the time they encountered a bait, regardless of bait type.