Taking the bait: species taking oral rabies vaccine baits intended for raccoons

Abstract

Raccoon rabies in eastern USA is managed by strategically distributing oral rabies vaccine (ORV) baits. The attractiveness, palativity, density, and non-target species bait take affect ORV effectiveness. We examined raccoon and non-target species differences in investigating/removing fish-meal polymer and coated sachet baits applied to simulate two aerial bait distribution densities. Bait densities of 150 baits/km 2 and 75 baits/km 2 were evaluated, respectively, in zones expected to have high and low raccoon densities. Three primary non-target species visited baits: coyotes, white-tailed deer, and feral swine. The proportion of bait stations visited by raccoons during 1 week observation periods ranged from 50 to 70%, exceeding non-target species visitation. Raccoon take rates for visited baits averaged from 59 to 100%. Raccoon visitation was similar for both bait densities, indicating a proportionally greater quantity of baits were taken in the higher bait density zone. Coyote visitation rates ranged from 16 to 26%, with take rates for visited baits between 46 and 100%. Coyotes were expected to take baits intended for raccoons, because similar baits are applied to vaccinate coyotes. Deer regularly investigated but rarely took baits. Feral swine were in low abundance in the high bait density zone (higher human density) and visited ≤ 1% of baits there but visited baits at frequencies similar to coyotes and deer in the low-density zone and were likely to take encountered baits (63-100%). Non-target bait consumption could be a concern in some circumstances for achieving sufficient raccoon sero-conversion rates.

Occurrence of mesocarnivores in montane sky islands: How spatial and temporal overlap informs rabies management in a regional hotspot

“…These areas where mesocarnivores co-occur should be considered in both proactive and reactive strategies for controlling the spread of rabies in Arizona. Diet overlap among carnivores could impact uptake rates of oral vaccines by specific species [71,72], but since all are susceptible to rabies this is a positive outcome. We recommend that rabies managers deliver oral vaccine baits onto the landscape when natural food resources are most scarce, particularly in the two drier seasons in Arizona (pre-monsoon spring and autumn).…”

Factors affecting bait uptake by the grey squirrel (Sciurus carolinensis) and the future delivery of oral contraceptives

“…For fertility control to be effective, a bait should be easily administered, species-specific and a sufficient proportion of the population must consume bait containing contraceptives with predominantly the females being targeted (Massei and Cowan 2014;Jacoblinnert et al 2022). Bait uptake by wildlife can be affected by many factors such as sex (Whisson and Salmon 2009), the time of year at which bait is deployed (Robinson et al 2017), bait density and distribution, the availability of alternative food sources (McRae et al 2020), and the density of the target species (Haley et al 2019). Understanding the relative importance of these factors for a target species is integral to the design of effective baitdelivery campaigns.…”

Detection of rabies antibodies in wild boars in north-east Romania by a rabies ELISA test

“…Among wild animals involved in vaccine bait consumption, the most majority in Europe are wild boars [35]. A recent study in the USA [36] suggested a variety of non-target species other than feral swine and including coyotes and white-tailed deer as bait competitors. Naturally, animals infected with rabies virus do not survive, since the lethality reaches 100%, therefore the presence of rabies antibodies in wildlife is the result of vaccine baits consumption.…”