Why is social behaviour in animals adversely affected by barren housing conditions?

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Impoverished environments, such as small barren cages, can adversely affect animals' interactions with each other. Interactions needed for productivity (e.g. mating, maternal care) can be impaired; interactions that reflect or cause good welfare (e.g. play) often decline; and aggression often increases. This holds for many species, but in laboratory mice, for instance, enriched-housed mice are better than barren-housed mice at producing and raising viable pups, and (especially if female) they fight less with cagemates. I will therefore investigate how the behavioural, cognitive & affective effects of being raised in barren environments impede social behaviour. My hypotheses are that 1) behavioural inflexibility (tendencies to form fixed routines, 'perseverate', and perform repetitive, predictable stereotypic behaviour) compromises the flexibility crucial for normal social, sexual & maternal behaviour; and 2) anxiety- and depression-like changes (anhedonia and negative judgment biases) reduce motivations for positive social interactions and cause predispositions to interpret neutral social cues as threatening. Mice (C57Bl/6, DBA/2 & BALB/c) will be used as ideal models: enrichment affects their social behaviour, their stereotypies often covary with perseveration, and females exhibit social learning, mate choice, nest-mate choice, & social buffering (where the presence of a conspecific reduces stress). Further, about 30 million are used in research each year, making improving their welfare highly impactful. My 26 HQP will test the predictions that a) enriched-raised females are less aggressive to cagemates & intruders; better at demonstrating information in social learning tasks; preferred over barren-raised females as cage-mates; and better ‘stress buffers’ than barren-raised females; b) enriched-raised males are more attractive to females, and also induce better maternal care in those that they mate, than barren-housed males; and c) enriched females are better mothers (e.g. faster & more responsive in pup retrieval tests), and that pregnant/lactating females prefer enriched females to barren-raised females as communal nesting partners. As potential mediators of all effects found, we will test the hypotheses that i) enriched mice are less perseverative (helping them make appropriate adjustments to changing social signals), and that ii) enriched mice find social contact more rewarding and less threatening than do barren-reared mice. How impoverished environments compromise social interactions has never before been systematically investigated, and the hypotheses under test are novel. This work has broad application, not just for laboratory mouse breeders & colony managers, but beyond to farm, zoo & other laboratory animals, via identifying environmental improvements as potential ways to boost both productivity and welfare by reducing social problems.