Weight loss in Oystercatchers <i>Haematopus ostralegus</i> on the roost and after capture

This paper analyses the weight loss in Oystercatchers on the roost and after capture and attempts to investigate to what degree this weight loss is due to defecation of digested food, to dehydration and to utilisation of nutrient stores. The study emphasizes the need to record weight changes relative to the time of arrival at the roost, rather than relative to time since capture, as is common practice in correcting for weight loss In captive birds. If food is still defecated, the weight loss is 4.3 times as large as when the gut is empty. From then on, probably 10% of the weight loss is due to dehydration. It is estimated that the rest of the remaining weight decrease is about equally due to loss of dry lean muscles and fat. The weight loss of waders of different size is a function of body weight(3/4).