Coastal Resource Information System
Cormorants
METADATACormorants are highly vulnerable to oil on water (King and Sanger 1979). Contact with oil results in very high mortality. Oil that washes up on nesting islands or cliffs may affect breeding cormorants because, although the nests are located above the splash zone and adults usually fly to and from them, they do occasionally land near the splash zone first.
Fledgling Cormorants may contact oil on rocks if they walk to the sea for the first time (in August through till September). Non-breeding cormorants (a large percentage of the local population) are vulnerable to oil throughout the year because they roost on rocks and log booms near the water line.
Cormorants are highly vulnerable to oil cleanup on breeding colonies from May through September. Nest building begins in April. Relatively speaking, disturbances at this time are not serious. Once the eggs are laid and incubation begins, Cormorants are easily disturbed from their nests. Unattended eggs and young birds may be killed and eaten by Glaucous-winged Gulls. Losses will be heavy and sudden on mixed Gull/Cormorant colonies. Even without predation, overheating of eggs and young on sunny days can result in high mortality when adults are off the nests for extended periods of time. By September, most Gulls have left the colonies, and predation pressure is reduced. Predation pressure by Gulls has been known to extend the breeding season into October in some colonies. During the rest of the year, Cormorants are not very vulnerable to cleanup activities because they can move to other areas or can become habituated to some disturbances.
Cormorant species present in Coastal BC:
Detailed species reports from the British Columbia Species and Ecosystem Explorer are available by following the above links.
BC Cormorant species are also breifly described below in exerpts from: The Birds of British Columbia, Vol. 2, Nonpasserines: Diurnal Birds of Prey through Woodpeckers by R. Wayne Campbell, Neil K. Dawe, Ian McTaggart-Cowan, John M. Cooper, Gary W. Kaiser and Michael C.E. McNall.
Brandt’s Cormorant
The
Brandt’s Cormorant occurs along the BC coast throughout the year.
It is known to frequent mainland inlets. Marine waters are preferred and
unlike the Double-crested Cormorant, Brandt’s avoids land. It frequents
bays, lagoons, harbours and narrows with strong currents where nearby
rocks or islets provide roosting sites. The center of abundance is the
Gulf Islands and Juan de Fuca Strait. Other significant but smaller concentrations
occur in Clayquot Sound and Barkley Sound. The Brandt’s Cormorant
breeds on the West Coast of Vancouver Island in Barkley Sound, off Long
Beach and at Race Rocks. Known colonies are all on bare rocky islands.
(Photo credits: Ministry of Environment, Lands and Parks, Province
of British Columbia)
Double-crested Cormorant
The Double-crested Cormorant is found in all coastal areas,
including inlets, but is most abundant in the vicinity of the Strait of Georgia and Juan
de Fuca Strait. It prefers marine habitats such as bays, inlets, harbours, lagoons and
estuaries. It frequently roosts with Pelagic and Brandt’s Cormorants on islets,
wharves, log booms, pillings, etc. (Photo credit: Canadian Wildlife Service)
Pelagic Cormorant
The
Pelagic Cormorant is widespread and occurs along the inner and outer coastal
areas of the province throughout the year. It rarely occurs very far up
inlets, and there are no records of freshwater locations. It prefers rocky
coasts and forages in bays, harbours, lagoons, surge narrows and coves.
It usually roosts on rocky unvegetated islets, reefs and cliffs but also
uses log booms, spits, promontories and man-made structures such as bridges,
wharves, and light stations. Twenty-eight percent of the population is
on the west Coast of Vancouver Island. (Photo credits: Rob Butler,CanadianWildlife
Service)