干旱区生态环境知识资源中心

Using the density of food left in a patch after foraging - i.e. the giving-up density (GUD) - as a behavioural indicator, short-term foraging studies on birds in the dry and wet fringing forests and savanna habitats of the Amurum Forest Reserve, Laminga, Nigeria, were used to evaluate whether widespread food abundance will affect their behaviour in these apparently-different habitats. The effect of the dry season on feeding activity and the effects of temperature within, and between, days were also investigated. Results showed that GUDs were highest in dry fringing forests, intermediate in wet fringing forests, and lowest in savanna. This difference may have been as a result of a difference in food abundance between habitats. The availability of water in the wet fringing forests may have affected the feeding behaviour of the birds in the wet gully habitat compared with those of the dry gully. The behaviour of birds in response to time of day was affected by temperature, as there was no difference between GUDs in open and covered habitats in the mornings at lower temperatures, but lower GUDs were recorded in cover (at higher temperatures) in the afternoon when birds may - due to thermoregulatory costs - retreat to cover more often. However, temperature had no effect on GUDs over season. A reduction in GUDs towards the end of the dry season, as food resources deplete, gives further credence to the observation that food abundance affects behaviour.