The Great Cormorant is the largest
cormorant species found in Australia and is widespread across the world and in
Australia. Other cormorant species found in Australia are Pied, Black-faced,
Little Pied and Little Black, which are all found on the Gippsland Lakes.
The Great Cormorant is the most numerous
cormorant on the Gippsland Lakes and at times numbers are in the thousands.
Many Great Cormorants are nomadic and vast numbers can congregate at inland
waterways to breed following flooding. For example it was estimated that 20,000
pairs formed an enormous breeding colony at Lake Menindee, NSW, in 1974. But
when we were at Kinchega National Park in winter 2014 most of Menindee Lake was
bone dry empty and Broken Hill was making plans for emergency supplies of
water.
As for other nomadic waterbird species, for
example Australian Pelican and Banded Stilt, one wonders how 40,000 Great
Cormorants come, more or less simultaneously, to one inland location to
participate in a mass breeding event.
During inland droughts many birds take
refuge at coastal waterways such as the Gippsland Lakes and this no doubt
explains why their numbers vary on the Lakes and why numbers are large now when
much of the Murray Darling basin is in drought again.
On the Gippsland Lakes Great Cormorants feed
primarily on fish. Fish taken may include commercial species so the birds are
seen as a threat to both commercial and recreational fishers and when their
numbers grow the inevitable call for culling is heard.
Mother nature often takes second place to human
self-interest. However in this case we need to keep in mind the role the Lakes
play in the survival of nomadic species whose range and habitat is large and highly
variable in line with climate. We need to see bird species behavior and numbers
in a much larger context, both spatially and over the time span of the boom and
bust, wet and dry, Australian climate cycles.
Many Great Cormorants congregate at Lakes
Entrance around the entrance and many rest on the old timber and rock sea walls
there. On a late summer boat trip earlier this year I photographed Great
Cormorants on the western sea wall and managed to capture photos of adults in both
breeding and non-breeding plumage and juveniles. Great Cormorants are
moderately wary birds so we don’t often get to see them up close. Photos
capture detail that allows us to see more clearly the differences between
adults, breeding and non-breeding, and juveniles.
The Great Cormorant in the following photo
is an adult in breeding plumage. Note the white nuptial feathers around the
neck, the white flank on leg and the dark flecks on the normally yellow throat
patch at the base of the lower bill. Birds in breeding plumage have dark black
glossy plumage. Also note the crest, which is always present, but not always
seen.
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| Adult Great Cormorant in breeding plumage which is retained for about three months - both sexes look similar. |
The next photo shows an adult Great
Cormorant in non-breeding plumage. Note there are no white nuptial feathers,
white flank on the leg or dark specs on the yellow throat patch.
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| Adult Great Cormorant in non breeding plumage. |
The bird in this final photo is a juvenile
Great Cormorant. Note the limited white patch behind yellow facial skin, the
brown and not black feathers and mottled brown and white breast and belly
feathers.
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| Juvenile Great Cormorant. |
While many may dislike the Great Cormorant
they are a handsome and very successful bird supremely adapted to catching fish
and other prey under water.