Stress and stereotypies in farmed mink

Abstract

Stereotyped and normal behaviours were quantified from April to June 1989 among 187 adult male and female ranch mink. It was shown that mink devote no more than 3% of the day to stereotyped behaviour. The frequency of stereotypies is markedly increased leading up to feeding time in the middle of the day and declines to very low levels in the afternoon. Environmental disturbances such as human proximity and transport and unloading at other farm sections, have strong inhibitory effects on the performance of stereotypies. The relation between stereotypies and stress is discussed, and it is suggested that chronic intermittent stress (e.g. stress induced by daily fresh food deprivation), is a prerequisite for the occurrence of stereotypies, but that additional conditions involving low level external stimulation are important. A total of 147 adult females were divided into two groups: one exhibiting a low level of stereotypy ( n = 24 ) and one exhibiting a high level of stereotypy (n = 24). These two groups were studied from the weaning of pups in June 1989 until mating in March 1990. Normal behavioural activity as well as specified stereotypies were compared and related to stressful experiences. Again, it appeared that acute stress reduces the occurrence of stereotypies. It was found, however, that stereotypies are differentially affected by stress. Stereotypies in caged mink G.J. Mason Sub-department of Animal Behaviour, University of Cambridge, Madingley Road, Cambridge CB3 8AA, UK ABSTRACT Stereotypy was studied in 105 adult mink on a commercial farm. Stereotypy largely involved locomotor movements such as pacing. Individuals differed in the amount performed, in the exact movements involved, and in the complexity and variability of behavioural sequences. All 102 stereotypic individuals showed stereotypy before the daily delivery of food. Pre-feeding, there were significant negative correlations between stereotypy and inactivity ( r= -0 .839 , P<0.001 ), and stereotypy and normal activity (r--0 .449 , P < 0.001 ). Immediately before food delivery, stereotypies were particularly rapid, and were usually performed in the part of the cage nearest to the approaching feeding machine. This would suggest that the stereotypy is related to appetitive behaviour. However, it is not simply the captive equivalent of hunting; mink also performed stereotypy in response to a number ofStereotypy was studied in 105 adult mink on a commercial farm. Stereotypy largely involved locomotor movements such as pacing. Individuals differed in the amount performed, in the exact movements involved, and in the complexity and variability of behavioural sequences. All 102 stereotypic individuals showed stereotypy before the daily delivery of food. Pre-feeding, there were significant negative correlations between stereotypy and inactivity ( r= -0 .839 , P<0.001 ), and stereotypy and normal activity (r--0 .449 , P < 0.001 ). Immediately before food delivery, stereotypies were particularly rapid, and were usually performed in the part of the cage nearest to the approaching feeding machine. This would suggest that the stereotypy is related to appetitive behaviour. However, it is not simply the captive equivalent of hunting; mink also performed stereotypy in response to a number of