Tuesday, 5 May 2015

Great Cormorant

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.
Note: enlarge photos with a left click of the mouse and then use the mouse wheel to scroll back and forth through the photos (can't view captions in this mode). For iPad tap on any photo and then select other images from thumbnails displayed at bottom of scene. To go back to post tap on X at top right hand corner of screen.
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.
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.
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.

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