VARIATION IN THE ENERGY-INTAKE OF CAPTIVE OYSTERCATCHERS HAEMATOPUS-OSTRALEGUS

The food intake of captive Oystercatchers Haematopus ostralegus was me asured, and with an estimated utilization efficiency, the energy uptak e from the ingested food calculated. Annual, seasonal and weekly varia tions in energy intake were observed, together with variations related with the type of food offered. The variations in intake are related w ith the variable requirements of the maintenance metabolism and with c hanges in body mass. In a period with low ambient temperatures includi ng a prolonged cold spell, the energy input by the food intake and use of body reserves could not meet the requirements of the maintenance m etabolism as calculated. The strategies the birds may have used to bal ance the budget of energy provisioning and energy expenditure in these circumstances, are discussed. The weeks with high energy intake in th e period of pre- winter bodymass gain, seem to coincide with full moon and probably reflect nocturnal feeding. The differences in food intak e related with the type of food are attributed to palatibility of the food.