The potential of estrogen-based conditioned aversion in controlling depredation: A step closer toward the “magic bullet”

Nicolaus, Lowell K.; Farmer, Peter V.; Gustavson, Carl R.; Gustavson, Joan C.

doi:10.1016/0168-1591(89)90002-6

Cited by 23 publications

(12 citation statements)

References 21 publications

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“…Once we increased the dose in the reinforcements, all dogs showed vomiting and/or diarrhea, and food rejection was subsequently higher. This dose‐dependence on CFA has been reported in other studies . The hematological and biochemical results of this experiment suggest that thiram, in the doses used here, is safe for domestic dogs, but its safety for other free‐ranging predators and other wildlife must be verified.…”

Section: Discussionsupporting

confidence: 85%

“…The detectability of the aversive compound by the target species has been one of the main handicaps of CFA application for reducing predation in the wild . Several compounds have been used in previous CFA studies but only 17α‐ethinyloestradiol and thiabendazole have been proved to be undetectable until now . Despite the acceptable results obtained with 17α‐ethinyloestradiol, the risk of reproduction interference prevents its safe use in the field .…”

Section: Discussionmentioning

confidence: 99%

“…CFA can be induced deliberately by adding a chemical substance to the target food or prey to produce rejection by the predator . This substance should cause short‐term adverse effects, the effective dose should be far below the lethal dose to avoid severe intoxication in the case of multiple bait consumption, it should be physically and chemically stable, and must be undetectable from an organoleptic point of view . In this sense, several chemical compounds have been used to induce CFA on carnivores, but due to their negative health and behavioral effects, their narrow margins of safety, and especially their detectability, their use as CFA agents in the field has been limited so far.…”

Section: Introductionmentioning

confidence: 99%

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Conditioned food aversion in domestic dogs induced by thiram

Tobajas

Gómez‐Ramírez

Ferreras

et al. 2019

Pest Management Science

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BACKGROUND: The conflict between predators and humans for resources such as game species or livestock is an ancient issue, and it is especially sharp in the case of medium-large wild canids. In order to manage this conflict, lethal control methods are often used, which can sometimes be illegal, such as poisoning. As an alternative, conditioned food aversion (CFA) is a non-lethal method to reduce predation in which animals learn to avoid a given food due to the adverse effects caused by the ingestion of an undetectable chemical compound added to this food. The present study aimed to test thiram as a CFA agent in penned dogs as a first approach to use this substance for reducing the predation conflict associated with wild canids. RESULTS: Thiram, with or without an additional odor cue, produced CFA in penned dogs for more than 2 months. Moreover, thiram seemed to be undetectable and safe after the third ingestion of a 40-60 mg kg −1 dose. Desirable adverse effects, such as vomits, appeared around 1 h after exposure. These characteristics make thiram optimal for its use in predation reduction through CFA. However, individual variability could prevent CFA acquisition by some animals.CONCLUSIONS: Thiram has the potential to be used as a CFA agent in wildlife management and conservation to reduce predation by wild canids. Since thiram produced CFA without the problems of detectability and toxicity caused by other substances, it may be an alternative to lethal control methods used to reduce predation on game, livestock and endangered species.

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Section: Discussionsupporting

confidence: 85%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Conditioned food aversion in domestic dogs induced by thiram

Tobajas

Gómez‐Ramírez

Ferreras

et al. 2019

Pest Management Science

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“…2,No.4 be effective even when several species of predators are present. This has been demonstrated earlier (Nicolaus et al 1989b) and is consistent with what we know about estrogen: (a) it is a hormone common to all mammals and produces CT A in orders as diverse as rodents and primates (Gustavson et al 1989, Nicolaus et al 1989a; (b) illness is delayed (Nicolaus et al 1989a), and so there should be ample time for predators that feed at different rates to consume a full dose before illness terminates feeding; (c) meal size generally correlates with body size, and so an adequate dose will be delivered when larger animals consume relatively more eggs that smaller animals requiring a smaller dose; and (d) the lethal dose of estrogen is so far above the effective dose that there is little risk of accidentally killing predators that may then be replaced by untreated individuals.…”

Section: Establishing a Baiting Strategysupporting

confidence: 87%

Estrogen‐Based Aversion to Eggs Among Free‐Ranging Raccoons

Semel¹,

Nicolaus²

1992

Ecological Applications

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Nightly video records of uniquely marked free-ranging raccoons (Procyon lotor) established the events leading to and resulting from estrogen-induced conditioned taste aversion (CTA) to eggs. Observations of animals voluntarily consuming eggs indicated that: (1) some raccoons in the population were more active egg predators than were others and so were the most likely to be treated; (2) a few eggs injected with 30 mg of estrogen were less effective in inducing egg avoidance than were larger numbers of eggs treated with only 10 mg of estrogen; (3) CTA to eggs became well established even though raccoons had become familiar with eggs at the feeding site; (4) treated males tended to abandon egg consumption abruptly, but females tended to sample eggs for a short time before they, too, avoided them at a distance; (5) CTA was not location specific, persisted when surrounding scent cues changed, and failed to extinguish among treated raccoons that were present while untreated individuals consumed untreated eggs freely during the lengthy post-test period; and (6) treated females that avoid eggs may deny their offspring the opportunity to become familiar with egg prey. Observations of egg consumption in the second year of study provided evidence of a prolonged CTA effect in treated animals. Our results enable us to more fully describe a potential non-lethal technology for controlling predation on the eggs of waterfowl or endangered and threatened species.

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“…The aversion agent used to generate CTA should produce severe short-term illness, the 67 effective dose should be much less than the lethal dose, should be physically stable and so survive 68 intact in baits in the field, and should be undetectable to consumers when present at the appropriate 69 concentration in the baits (Nicolaus et al, 1989). Many substances are known to induce severe, short-70 term illness in a wide range of animals (e.g.…”

mentioning

confidence: 99%