The Great Cormorant is May's bird of the month.
Name:
Great Cormorant
Genus:
Phalacrocorax carbo
Description:
Cormorants are aquatic birds with long necks, stout black legs and webbed feet, with a long hooked bill for catching fish.
The Great Cormorant is the largest of the five members of the cormorant family in Australia, and it has established nesting colonies in Centennial Park. While there are two all-black species of cormorant in the Parklands, and the Great can be separated from the Little Black Cormorant by its much larger size, and the patch of white and yellow on its face behind the grey bill. During the breeding season the Great Cormorant develops more white on its face, and white patches on its thighs.
Distribution:
The Great Cormorant is widespread around the world, ranging from eastern North America, across Europe, Africa and Asia to Australia and New Zealand. The Australasian sub-species can be found across most of Australia where suitable areas of open water can be found, with the densest populations in the south-east and south-west.
They are equally at home in fresh or salt water, being seen inland in rivers and lakes, or swimming close to shore in estuaries and along the coast.
Feeding:
The Great Cormorant feeds mainly on fish, but will also take crustaceans, frogs and aquatic insects. They have been seen snapping up young turtles in the Centennial Park ponds. To aid their pursuit of fish their feathers can absorb water to reduce buoyancy, so they are often seen perched with wings spread to dry. They are quite agile in the water, using their powerful legs and webbed feet for speed, and using their wings as rudders to rapidly change direction.
They have been used in various cultures to catch fish, with the fishermen putting the cormorants on a leash, with a restrictive collar to prevent them from swallowing larger fish, which are then retrieved by the fishermen. This tradition is still carried on in China and other countries, although the practice is in decline.
Breeding:
Great Cormorants are colonial nesters, and will nest along cliff ledges on the coast, or inland, as in Centennial Park, in trees on islands or lake and river banks. Males will select a nest site, often an existing nest, and perform a vigorous display of wing flapping, tail raising and waving the head from side to side, giving raucous calls.
Pairs are monogamous at least for the breeding season, and some form lasting bonds. When a pair is formed both work to build or repair a large nest of sticks, and share incubation of the two to six eggs for about a month. After hatching the juvenile cormorants remain in the nest for about fifty days, and then, after fledging, remain under the care of the adults for about another fifty days, learning the skills to survive.
The accumulation of droppings from the nests can, over time, damage the nesting trees, evident on some of the islands on Duck Pond. When the trees, stripped of foliage, leave the nests exposed, the Cormorants will move to a new location.
They share their nesting sites with Pied Cormorants, the large black and white cormorants, often with one species nesting, and when the nests are abandoned, the other species moves in to use the same nests. Perhaps differences in the times of abundance of preferred prey lead to this rotation of nesting. But even among the dominant nesting group you can find occasional individuals of the other species nesting, along with Australasian Darters and Australian White Ibis.
In the Parklands:
Great Cormorants can be found across all the ponds in the Parklands, or seen flying to and from their fisheries along the coast. For many years their main nesting colony was on Duck Pond, but with the degradation of trees on the islands they have spread to other ponds in search of suitable nest sites.
This information was curated by a team of passionate Centennial Parklands volunteers and with the assistance of Volunteer Program and Asset staff. Find out more about our volunteer programs here.