Optimal digestion strategies in seabirds: A modelling approach

ft has been shown that there can be marked differences between seabird spec ies in gut retention times and digestive efficiencies, even when eating the same amounts of the same foods. We use mathematical modelling to explore t he relationship between optimal avian digestion strategy and various ecolog ical factors. The key factor determining the performance of a given digesti ve strategy is an 'ingestion bottleneck', which forces individuals to reduc e their ingestion rate once their gut is full of digesta. The severity of t he bottleneck is related to the retention time of digesta, with the result that an individual's optimal time and energy management differs according t o digestive physiology. The model predicts that rapid (and thus inefficient ) digestion is likely to be favoured when the energy cost of commuting betw een feeding and nesting sites is large, whereas slow (but efficient) digest ion is preferable when these costs are small.