A highly gregarious species, the Socotra cormorant lives, breeds and often forages in enormous, dense colonies of up to tens of thousands (2) (5). While this bird is primarily sedentary, large seasonal movements are made within the breeding range, which are thought to be related to fish migrations (2) (5). Large assemblies of birds roam far in search of huge shoals of fish. Once found, some birds settle on the water’s surface and dive for fish from there, whilst others plunge-dive from the air (5).
Very little information currently exists on the breeding behaviour of this bird. The northern population mostly nests during the winter months, while the southern population breeds in summer. Nests are packed close together within the colony, and comprise a circular scrape or depression in the ground with raised edges, concreted with excrement. Close proximity of nests inevitably results in much conflict and ‘bickering’ between neighbours, with returning birds frequently descending upon the wrong nest by accident and being chased off by the rightful owner. The incubation period is unknown, but thought to be around 28 days (5). At some stage of growth, parents leave their chicks in ‘crèches’ while they go out to forage, where they are guarded by a few adult birds from predation by large gulls (Larus spp.) (2) (5). Chicks are fed by partial regurgitation, after aggressively demanding food from their parents. Time to fledging is also unknown, but is probably somewhere around two months. Adult plumage is thought to be attained by the third year, but the age at which first breeding occurs is unknown (5).