Acceptance by stoats (Mustela erminea) of 1080 (sodium monofluoroacetate) in small-volume baits and its effect on behaviour and time to death.
OBJECTIVE
To assess whether stoats (Mustela erminea) would eat small baits containing 0.1% sodium monofluoroacetate (1080); whether they would die from it; how long it would take to kill them; and to document the behaviour of 1080-intoxicated stoats.


METHODS
Stoats were offered 1-g baits of two semi-fluid formulations containing 0.1% 1080, presented in open dishes, and their subsequent behaviour was monitored by video and direct observation. Muscle samples from stoats that died were analysed for 1080 residues.


RESULTS
There was no significant difference between two types of bait with regard to acceptance, mortality, and time to death, and behavioural effects were similar; consequently, results from the two types of bait were combined. Twelve of 14 stoats offered the baits ate them voluntarily, and a 13th licked bait off its fur; all 13 died between 1 h 15 min and 4 h 7 min (mean 2 h 38 min) later. At first (range 29 min - 2 h 7 min, mean 1 h 1 min), their behaviour appeared to be normal. Ataxia and hyperactivity were the first behavioural signs of poisoning, and lasted 2 min - 1 h 40 min (mean 26 min). This was followed by recumbency with convulsions and rapid breathing (range 16 min to 2 h, mean 58 min), then recumbency with limited activity and progressively shallow breathing prior to death (range 1-51 min, mean 33 min). Stoats became non-responsive to a light being turned on, or to touch once recumbency became sustained. Residues of 1080 were found in muscle tissue of all 13 dead stoats, at concentrations ranging from 0.075 microg/g in a 287-g male that died 4 h 7 min after eating only 0.74 g of bait, to 2.5 microg/g in a 254-g female that died 2 h 42 min after taking a whole 1-g bait.


CONCLUSIONS
Stoats will voluntarily take small (1-g) baits containing a lethal dose of 1080 at 0.1%, and die from it comparatively rapidly for a mammalian carnivore.
Potter
M A
MA
Ecology Group, Institute of Natural Resources, Massey University, Private Bag 11222, Palmerston North, New Zealand. m.potter@massey.ac.nz
Barrett
D P
DP
King
C M
CM
D000818:Animals; D000835:Animals, Wild; D001835:Body Weight; D004305:Dose-Response Relationship, Drug; D004350:Drug Residues / Q000032:analysis*; D005260:Female; D005463:Fluoroacetates / Q000506:poisoning*; D008297:Male; D018482:Muscle, Skeletal / Q000737:chemistry*; D045969:Mustelidae; D012378:Rodenticides / Q000506:poisoning*; D013997:Time Factors
D005463:Fluoroacetates; D012378:Rodenticides