Published online by Cambridge University Press: 11 January 2023
During homing contests, racing pigeons (Columba livia) are transported to their release site under crowded conditions. Behaviour and thermogenesis under these conditions were studied in two experiments. In the first experiment, temperature (26 °C or 36 °C) and water availability (access or deprived) had no significant effect on either behaviour or heat production of old male pigeons. However, the frequency of threatening behaviour and the proportion of activity-related heat production in total heat production increased during the 23-hour experimental period, whereas no decrease in aggressive behaviour was found. In the second experiment the effect of testing age (young or old) and sex (male or female) were considered in relation to behaviour and thermogenesis. Young pigeons were more immobile than old pigeons, but heat production was lower in old pigeons. Male groups had a higher activity-related heat production and had more head injuries resulting from pecking than females. Again, no decrease in aggressive behaviour or changes in behaviour patterns over time were found. Body-weight at the start of the experiment was predictive of subsequent behaviour in the crate. A higher body-weight was related to more threatening behaviour, less displacement and less head injuries. The consistent level of aggressive behaviour over time, causing predictable head injuries, indicates that a ‘ceiling effect’ in adaptation is reached under crowded transport conditions. To improve pigeon welfare, serious considerations must be given to transporting racing pigeons under less crowded conditions.