Behavioural and physiological effects of absence of ultraviolet wavelengths for domestic chicks

It is increasingly clear that ultraviolet (UV) wavelengths are a component of normal avian colour perception and influence their behaviour. As artificial lighting is designed to human specifications, and so is usually deficient in UV light, there may be welfare implications for captive birds, with both context-dependent and chronic long-term effects in its absence. Domestic chicks, Gallus gallus domesticus, kept under UV-deficient environments had significantly higher basal plasma corticosterone concentrations and tended to explore less, although not significantly so, suggestive of suboptimal conditions. Chicks under full spectrum lighting had a significantly higher rate of corticosterone rise in response to capture and handling stress than chicks reared without UV, largely because a similar maximum level was reached from lower initial concentrations. These treatment differences in hormonal stress response tended to diminish with age and/or familiarity with humans, in both groups of birds. (C) 2001 The Association for the Study of Animal Behaviour.