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Locomotor Activity of Captive Greenfinches Involves Two Different Behavioural Traits



Peeter Hõrak, Department of Zoology, Institute of Ecology and Earth Sciences, Tartu University, Vanemuise 46, 51014 Tartu, Estonia.



Activity budgets of animals often show consistent differences between individuals across time, which qualifies them as personality traits. In the case of captive birds, locomotor activity can be divided into two major components – frequency of hopping and flapping flight bouts, which may conceive different information about individual condition. This idea was tested in a 2*2 factorial experiment in wild-caught captive greenfinches (Carduelis chloris), injected with bacterial lipopolysaccharide (LPS) and/or temporarily exposed to an image of a predator. We predicted that LPS injection would reduce both types of activity via induction of sickness syndrome and that predator image treatment would either increase or decrease different components of activity. Both behavioural traits were similarly consistent in time over a 10-d period but the correlations between them depended on measurement context. LPS treatment reduced flapping and hopping frequencies and total locomotor activity. Exposure to the predator image had no effect on flapping frequency, but it decreased hopping frequency and total locomotor activity among the birds that were initially most active. The effects of both treatments on behaviour were relatively long-lasting, that is, detectable at least 87 h after LPS injection and 44 h after exposure to the predator image. Our findings demonstrate the existence of two components of locomotor activity that responded similarly to the physiological but differently to the psychological stressor. The distinction between such components thus increases the information content of activity recordings of caged birds, which is likely to reveal novel aspects of covariation between different aspects of stress responsiveness and other performance parameters.