Survey
Two significant connections were found from analysing survey responses. The first, larger mink population size at centres is linked to breeding success. Secondly, the count of mink at centres compared to the most common number of nest boxes per enclosure. However, note that the trend of increased population size leading to higher breeding success was not found to be significant after the p-values were adjusted using Bonferroni correction. Breeding success being linked to population size has been documented in other species in captivity and the wild. The higher population size may improve breeding success due to the higher gentic diversity and increased number of mink to choose from if mating is unsuccessful. The correlation between mink count and nest boxes is expected as having more mink should require more nest boxes. Additionally, the more mink a facility can house, the more likely it is to have extra funds, which can be spent on research and additional supplies such as nest boxes.
I found no cause for abnormal repetitive behaviours and low breeding rates in European mink when comparing them to enclosure design, and keeper management. In contrast with my findings, habitat complexity has been found to play a significant role in animal welfare and behaviour. Male aggressive and passive behaviours has been linked to decreased breeding success, and that breeding success was more dependent on males than females. This is supported by the survey, where the most common listed cause for failed breeding events in the last 10 years was male behaviour. Research found that wild-born males successfully mated more frequently than captive-born males (89% and 35%, respectively). Captive-born males expressed more aggression and passivity (deemed abnormal behaviours) which may be caused by some factors linked to captivity.
Giving environmental enrichment to American mink has also been shown to improve welfare and male copulation success by decreasing stereotypic behaviours. The effects of the enrichment may not be accurately represented as some of the participants’ short-answer responses did not match when comparing the enrichment they provided and what enrichment resulted in the most positive behavioural outcome. The questions relating to the view from public did not result in any significant links, but this is refuted by other studies. Visitors can have both a negative and positive impact on animal behaviour and welfare. Negative responses often stem from the animals fearing the humans, resulting in aggression, hiding, or reduced foraging and grooming. While visitors may be seen an enriching to some species, as they engage in attention-seeking behaviours with them.
European mink captive breeding and husbandry protocol (2006)
This protocol gives recommendations for how to this species in captivity. I compared the survey participants’ answers to it to determine if there were differences in management practices.
For the enclosure design, firstly, almost all participants in the survey had exhibits out of view from the public. Two of the participants describe having on show exhibits with a smaller area than recommended for female mink with kits, though information on whether these are used for individual males or females is unknown. Six out of the 11 participants that answered the question related to water features in their enclosures exceeded the recommendation. Substrate and furnishing recommendations describe primarily a natural type of enclosure with suggestions for concrete or mesh under the soil to prevent mink from digging out, this was followed by all participants. Nest boxes are described in detail in the protocol but information on the quantity of nest boxes per enclosure is missing. All participants followed the bedding recommendation, of using soft and dry natural materials.
The protocol highlights the importance of environmental enrichment, but since structural enrichment is static, additional enrichment should be introduced. All participants but one, which answered the enrichment questions, stated providing enrichment. Interestingly, the most common enrichment to receive positive outcomes is manipulable enrichment, followed by foraging and food. I find it surprising that the protocol does not recommend manipulable enrichment, though they mention foraging and food-related enrichments. The dietary requirement section of the protocol describes the percentage of different food types. European mink should be consuming: 33% fish, 50% ground meat, and 50% Mazuri Carnivore Feline Meat F (pellets). The total exceeds 100%, but the directions say to alternate fish and rodent/chicks every two days. Noticeably, only two participants indicated feeding their mink seafood products.
For keeper-related work, the protocol has recommendations for cleaning and restraining/transporting European mink. Cleaning recommendations are less strict in the protocol except regarding nest boxes, which should be cleaned daily once kits are able to move and eat solid foods. This recommendation was not followed by any of the participants in the survey. Survey participants’ nest box cleaning ranged from every 4 to 15 days, while whole enclosure cleaning ranged from daily to fortnightly days. The protocol does not include training, however this is being conducted in 5 of the 13 facilities.
Video
The analysis of the video data showed that, contrary to the survey’s behavioural question results, there were significant behavioural differences between the successful and unsuccessful breeding males. My research shows that not only the presence of enrichment matters, but also variety. Male mink with frequently more types of enrichment were more likely to successfully breed. The effect of presence or absence of enrichment has been studied in relation to behaviour and breeding success, however differences in quantities of enrichment has not. Enrichment quantity and the duration individuals interacted with enrichment affected the probability of successful reproduction. Enrichment interaction duration and enrichment quantity did not significantly affect differences in overall activity (i.e. counts of locomotion, climbing, or inactivity) between the groups. Studies have found that the presence of environmental enrichment increases activity and variety of behaviours in American mink. This effect was not seen in my study potentially because none of the groups had no enrichment. The rubbing and shaking behaviours were observed to be significantly affected by enrichment quantity. This behaviour was primarily observed after elimination behaviour and when there was snow on the ground. However, there is no research on these behaviours, I believe these behaviours may be linked to grooming but I am uncertain of their impact on the welfare of European mink. With more enrichment quantity (categorical), enrichment manipulation increased.
Stereotypic behaviour was not significantly affected by enrichment quantity or duration of interaction. Eight out of the ten males were observed pacing at least once during the observation period. While only five of the ten were observed performing stationary abnormal behaviours at least once. These non-significant results are contrary to what has been observed in American mink, where, as the duration of enrichment interaction increased, locomotion stereotypic (i.e. pacing) behaviours decreased. However, comparing the breeding groups to stereotypic behaviours, pacing was significantly affected. Though the cause may not be certain, since comparing pacing to enrichment type and quantity yielded no significant results. Pacing may be used as an indicator of lower chance of breeding success. This is supported by research on American mink, which found that pacing was a predictor for copulation, with males that paced more having fewer copulations than males which paced less. Breeding group also affected the climbing on, and inside enrichment behaviours, with the former being observed more in breeding males, and the latter more prevalent in non-breeding males. More research is needed on the impact of specific types of interactions with enrichment on breeding success.
Conclusion
The population size of European mink per facility showed a significant connection to breeding success. This may be due to increased possibility to change pairs, higher genetic diversity, or simply higher chance of birth due to the higher number of individuals. My survey results suggest that enclosure design does not significantly affect European mink behaviour, specifically stereotypic behaviours, and breeding success. Further, it suggests enrichment, diet, and keeper management does not affect this species’ abnormal reptitive behaviours and breeding success in captivity. The video behavioural analysis found that enrichment did have an impact on behaviour and reproductive success. My enclosure design results from the survey and enrichment affect observed from the videos contradict each other. Therefore, more research on captive European mink is needed on these topics, with larger sample sizes, more targeted surveys and behavioural recordings.