Abstract: ENERGY requirements of altricial nestlings should have effects on optimal reproductive strategy and foraging efficiency of adults, and on developmental physiology of nestlings (Royama 1966, I)unn 1973). Most food consumption studies measure weight of food intake without considering nutritional value. Because avian foods vary widely in digestibility, nutrition, and caloric content, such measures of food consumption of different species are not always comparable. In addition, many studies examine only total quantities of food eaten during growth (e.g. Kale 1965, Brenner 1968) or deal with birds raised in captivity (e.g. Kahl 1962, Junor 1965). The latter may not indicate natural levels of food consumption, as it is difficult to duplicate normal foods and feeding rates. For example Junor's (1965, 1972) studies indicate that the amount of food captive young Reed Cormorants, Phalacrocorax africanus, consume differs markedly according to the number of times per day they are fed. I am aware of only a few studies to date that have estimated daily consumption of altricial nestlings under natural conditions (Royama 1966, Koelink 1972, van Balen 1973, Westerterp 1973), and only the latter provided data on the caloric value of the foods eaten. This paper gives the results of a field study on food consumption of free-living nestling I)ouble-crested Cormorants, Phalacrocorax auritus. (Unless noted otherwise, all references to cormorants mean this species.) Feeding frequency and size of food items were used to indicate quantities eaten, and analysis of food samples and digestive efficiency allowed conversion to caloric intake. The report is mainly descriptive, and the correlation of results to other aspects of the breeding strategy of cormorants will be reserved for a later paper.