The Importance of Nocturnal Foraging in Shorebirds: A Consequence of Increased Invertebrate Prey Activity

Abstract

Many shorebirds are known to feed at night. However, the extent to which this contributes to the total daily energy intake of different individuals under different weather conditions and at different times of year is largely unknown. Several authors, using a variety of methods, have attempted to quantify nocturnal food intake of Oystercatchers, Haematopus ostralegus. Drinnan (1957) observed no difference between night and day in the number of shells opened and left on the mud, as did Davidson (1967) by direct observation, using infrared equipment. However, Heppleston (1971) and Hulscher (1974) using captive birds, obtained night values of 0.58 and 0.86 respectively, of the intake during the day. In Knot, Calidris canutus, feeding on Macoma balthica, Prater (1972) found that the stomach contents of birds shot after daylight feeding periods contained four times the quantity of prey found in night feeding birds.