Meeting Abstract
Animals often engage in specific behaviours, or have specific life-history stages, that impose substantial metabolic demands often for prolonged periods of time, e.g. during migration, reproduction and foraging. It seems intuitive that to be able to cope with these elevated metabolic demands, efficient oxygen transport and high aerobic capacity are essential, and that some individuals will be more physiologically adapted to meet these demands than others. Here we focused on the role of hematocrit (Hct) and hemoglobin (Hb), key determinants of oxygen-carrying capacity; specifically we investigated individual variation in, and relationships between, hematology, metabolic rate and aerobic capacity in relation to workload in zebra finches, Taeniopygia guttata. First, we measured basal metabolic rate (BMR), Hct and Hb in 16 males and 16 females. Then we subjected half of the subjects to high foraging cost condition (HF) and the other subjects to control forging condition (CTR). As soon as the birds adapted to the HF condition, we again blood sampled all birds and measured BMR. Initial analysis showed that although birds subjected to HF condition experienced higher workload and spent more time foraging (based on behavioural observation), their Hct and Hb did not differ from either baseline values or birds housed in CTR condition. We speculated that the uncoupled relationship between hematology and workload could be due to a lag between increased workload and physiological changes. We plan to measure BMR, Hct and Hb in all birds again at 60 days post-manipulation, after birds are housed in HF condition for an extended period of time, to determine if there is longer-term physiological adaptation associated with increased workload.
