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In cap­tiv­ity con­tented males fare bet­ter with the ‘ladies’

pub­lished 29 Novem­ber 2013 | mod­i­fied 03 Novem­ber 2014

A first-​ever study from the Uni­ver­sity of Guelph (UoG) reveals that relaxed, con­tent male mink raised in enriched envi­ron­ments – cages com­plete with pools, toys and swings – are more suc­cess­ful in the mat­ing season.

American minkThe research, led by ani­mal wel­fare expert Prof. Geor­gia Mason and her doc­toral stu­dent Maria Diez-​Leon, was pub­lished on 25 Novem­ber in the sci­en­tific jour­nal PLOS ONE. 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.

We can’t tell if the enriched males are more attrac­tive, keener on mat­ing or both. But the secret to their suc­cess is their calmer, more nor­mal behaviour.
« Prof. Geor­gia Mason, behav­ioural biol­o­gist, Ani­mal behav­iour and Wel­fare Fac­ulty, Uni­ver­sity of Guelph

“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, who spe­cialises 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.

American mink cageMales 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.”

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.
(Maria Diez-​Leon, doc­toral stu­dent, Ani­mal behav­iour and Wel­fare Fac­ulty, Uni­ver­sity of Guelph)

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. In another UoG study with mink cap­tive spec­i­mens showed signs of boredom.

(Source: Uni­ver­sity of Guelph news release, 28.11.2013)

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