Effects of environmental enrichment and stereotypic behavior on maternal behavior and infant viability in a model carnivore, the American mink (Neovison vison)

Abstract

In several species, stress compromises maternal behaviors that are important for infant viability (e.g. licking and grooming). Understanding how stress in captivity affects maternal behavior could therefore be beneficial, especially for carnivores in zoos and breeding centers where infant mortality is often high. We used a model carnivore--American mink--to test two hypotheses, namely that maternal investment and/or behavior is i. improved by environmental enrichment; and ii. compromised by stereotypic behavior. We observed 22 females raised in an indoor facility, 9 enriched, 13 non-enriched. At birth, and at post-natal day 20 when altricial infants were still fully dependent on their mothers, the following offspring variables were recorded: litter size, infant mortality, litter sex ratio (post-natal day 1), and weight. Maternal behavior was assessed by recording nest shape (post-natal day 1), and the frequency of licking and grooming (post-natal days 1-7). Non-enriched females stereotyped more, had female-skewed litters at birth, and tended to make poorer, flatter nests. Maternal licking and grooming showed large, stable individual differences, but appeared unaffected by enrichment. High levels of maternal stereotypic behavior predicted slower offspring growth, replicating previous findings for farmed mink. Nevertheless, enrichment did not significantly increase infant growth rates nor decrease infant mortality. Due to small sample sizes, our study now needs replicating, particularly to explore the potential benefits of enrichment on nest building, sex ratio effects, and the implications of maternal licking and grooming for offspring stress reactivity. Findings could then apply to endangered mustelids like the European mink.

Using Zoo Welfare Assessments to Identify Common Issues in Developing Country Zoos

“…Zoo animal welfare is one of the key components in modern zoos achieving their aims (conservation, education, research and recreation). For example, with low welfare standards, an animal’s reproductive success decreases [ 7 , 8 ]. Godinez et al [ 9 ] also found that increases in animal stereotypies decreased visitor enjoyment, reducing the zoo’s opportunities to contribute towards both in situ and ex situ conservation strategies [ 10 ].…”

Neurophysiological correlates of stereotypic behaviour in a model carnivore species

“…But mink also show an idiosyncratic scrabbling or digging with the forepaws. Unlike loco SB, this sub-type of SB is not Carnivora-typical; is unrelated to perseveration [42]; is elicited by the proximity of neighbours [64]; does not predict failure in mating competitions [65]; and is not reduced long-term by enriched-rearing, if enriched-raised mink are transferred to barren conditions [59].…”

“…Briefly, the NE environments consisted of a wire mesh home cage (61x76x46cm) with an attached nestbox (bedded year round). E environments consisted of this basic home cage with a series of overhead structures (including ramps to climb up and down and a 2.5m tunnel) providing each animal with free access to an extra compartment double the size of his home cage, and containing an extra nestbox, a swing, circulating water in which to wade, and several manipulable objects, some familiar, some new each month [60,65]. These E conditions are preferred by mink [10] and reduce their physiological stress [59].…”

“…The killing and extraction methods are described elsewhere [65]. Brains were cut at the caudal end of the medulla, extracted, flash frozen and preserved in dry ice for transport from the farm and then stored at -80˚C until further processing (sample sizes for each recorded variable are given in Table 1).…”

An Exploration of the Value of Elective Health Checks in UK Zoo-Housed Gibbons

“…The early detection of other progressive conditions such as renal failure also allows for medical and husbandry interventions designed to slow deterioration, to be put in place, thereby maximising both quality and quantity of life. Any improvement to animal health and welfare is also likely to have a positive impact on breeding success [41,42] and, by encouraging more species-specific natural behaviours, might also enhance visitor perception and experience [43].…”