Study finds contented males more attractive
A first-ever study from the University of Guelph reveals that relaxed, content male mink raised in enriched environments – cages complete with pools, toys and swings – are more successful in the mating season.
The research, led by animal welfare expert Prof. Georgia Mason and her doctoral student Maria Diez-Leon, was published recently in PLOS ONE, an international journal published by the Public Library of Science.
The findings may help improve mating among captive animals, especially those with breeding problems such as giant pandas and Canada's rare black-footed ferrets.
"With many captive carnivores, it can be hard to get males to mate: some are too aggressive, while others just seem not that interested," said Mason, a behavioural biologist specializing in how animals adapt to captive housing conditions.
"Our findings suggest that improving their welfare via better housing could help make the difference. We also hope our results will encourage more use of enrichments on mink farms."
The study involved 32 female and 32 male American mink, with half of the latter raised in enriched cages. Over two years, the same males were offered as mates to two different sets of female mink.
Females were free to wander and choose between enriched or non-enriched males.
At mating time, the males were presented in identical cages. "Each female could only see her suitors, not whether or not they had cool real estate and a swimming pool," Mason said.
Males raised with enrichments mated nearly twice as often as non-enriched males.
"We can't tell if the enriched males are more attractive, keener on mating or both," said Mason. "But the secret to their success is their calmer, more normal behaviour."
Enriched males avoid the repetitive pacing and head-twirling common among mink raised in non-stimulating environments. Such behaviours reduce males' success with females, Mason said.
Males from enriched houses are also physically bigger and heavier, with bigger spleens indicating better immune systems. They have higher testosterone levels, suggesting greater libidos, and they even have better developed penis bones.
"How important these other changes are to females is something we hope to look at next," said Mason.
"But first and foremost, living a good, low-stress life, one that results in a healthy, well-developed brain, is what really helps them succeed."
Diez-Leon added: "Our results confirm what has been long suspected: that males raised in barren environments are at risk of developing into physically and psychologically unattractive adults, which affects breeding in captivity."
"Enriched housing conditions could provide a solution, with the added benefit of enhancing animals' welfare."
The researchers studied mink because housing enrichments that improve their welfare are well-understood and because females are known to be choosy about mates, said Mason. She holds the Canada Research Chair in Animal Welfare in Guelph's Department of Animal and Poultry Science and is a faculty member in U of G's Campbell Centre for the Study of Animal Welfare.