Pellets versus feces: their relative importance describing the food habits of double-crested cormorants

We compared the amount of taxonomically identifiable (diagnostic) fish remains in double-crested cormorant (Phalacrocorax auritus) feces to that exiting the birds via regurgitated pellets. Feces and pellets were collected concurrently during June 1994 from cormorant colonies on Little Galloo Island, eastern Lake Ontario. About 90% of the diagnostic fish remains were found in pellets and 10% in feces. However, only 4% of the diagnostic remains in the feces represented fish that could not be accounted for in the pellets. Pellets provided better information than feces for determining diet composition. Because of the increased effort to collect and analyze fecal material, and the limited amount of additional information provided, examination of feces in addition to pellets is probably not necessary in most studies of double-crested cormorant feeding ecology.