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OBSERVATIONS ON THE BEHAVIOUR AND ECOLOGY OF THE FLIGHTLESS CORMORANT NANNOPTERUM HARRISI
Author(s) -
Snow Barbara K.
Publication year - 1966
Publication title -
ibis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.933
H-Index - 80
eISSN - 1474-919X
pISSN - 0019-1019
DOI - 10.1111/j.1474-919x.1966.tb07270.x
Subject(s) - cormorant , nest (protein structural motif) , courtship , archipelago , ecology , biology , breed , predation , mating , perch , zoology , courtship display , geography , fishery , fish <actinopterygii> , biochemistry
SUMMARY From 25 September to 8 October 1963 daily observations were made on a group of Flightless Cormorants Nannopterum harrisi nesting on the west side of Albemarle Island in the Galápagos. Flightless Cormorants are apparently bottom‐feeders, and confined to shallow coasts at the western end of the Galapagos Archipelago where there is an upwelling of cold nutrient‐rich water. There is no reason to suppose that they are declining in numbers. Males are very much larger than females, the size difference between the sexes being greater than in other species of cormorants. Courtship behaviour, nest‐building and mating are described. The earliest phases of courtship take place on the water, later phases at the nest‐site. Homologies are traced with other cormorant species. In contrast to other members of the family, allopreening apparently does not occur. Both sexes incubate and care for the young. Observations on families of different ages over the 12‐day period allowed the development of the young to be traced up to the age of about 40 days. Egg‐laying takes place in most months of the year, with a peak in April‐June and perhaps a second peak about October. Observations on birds colour‐ringed on an earlier visit suggested that individuals do not breed more than once in the year. Nesting success appeared to be very low in 1963.