Spot these 5 cormorants around Port Phillip Bay
Why do cormorants sunbathe?
These birds are often seen loafing on piers and pontoons from Portsea to Point Lonsdale, wings outstretched, drying off after a bout of fishing. Unlike the sun-loving bronzed Aussies on the beaches of Port Phillip Bay, outstretched on their towels to maximise sun exposure, our local cormorants are not assuming this posture for relaxation or cosmetic reasons. They are perched with wings spread to speed the drying process.
Cormorants catch their food underwater. They dive after their prey, powered by large, webbed feet. If you stand on a pier and watch a cormorant going about its underwater business, you’ll be struck by how sleek such a large bird can look. The torpedo shape they take on is aided by the fact that their feathers are partially permeable to water. This means that water is able to push out pockets of air from among the feathers. This nifty little evolutionary adaptation reduces the bird’s buoyancy, helping it to submerge more easily in a dive. By minimising the amount of energy spent getting down to the preferred fishing depth, this property of the cormorant’s feathers allows it to spend that saved energy on chasing fish.
It is often assumed that the water-absorbing characteristics of a cormorant’s plumage arise due to a low quality or quantity of waterproof preen oil (the stuff used by birds to maintain feather condition). However, cormorants have a fully functional preen gland. It is now thought that the unique qualities of a cormorant’s plumage are the result of structural adaptations of the feathers themselves.
Close to the feather quill (called the rachis) the fluffy bits (barbs and barbules) are tightly packed. But as you get further out towards the margins of the feather, they become more widely spaced, allowing water to penetrate between the gaps. Together, these features mean that a cormorant is able to maintain a waterproof portion close to the quill that stops cold water contacting the skin, while preventing excessive amounts of air from being trapped by the edges of each feather.
Feathers that provide easy access to fishing spots sound perfect, don’t they? They certainly have their advantages, but they also come at a cost. When back on land, water-soaked plumage makes a cormorant heavier. If an alert sea eagle is around, that extra weight could mean the difference between life and death as it makes flight more difficult.
However, perhaps the most problematic thing about being cloaked in wet feathers is the energy that the bird must expend if it uses its own body heat to dry them. Rather than waste energy on drying, cormorants harness the drying power of the wind and sun. By spreading their wings and facing into the wind, cormorants maximise the feather surface area over which the breeze can draw away moisture trapped among the feathers.
Find these Port Phillip locals
The Great Cormorant
There are two species with completely black plumage. The larger of these, the Great Cormorant, is usually found alone or in small groups. Look for it in large, permanent freshwater habitats, such as Newport Lakes Park and Braeside Park, and in the Bay itself.
The Little Black Cormorant
The other all-black species is the Little Black Cormorant. Unsurprisingly, it is smaller than the Great Cormorant. It often hunts in groups, and flocks of several hundred sometimes form. Birrarung Marr is an easy place to see this species, but it can be found in just about any wetland or water body.
The Pied Cormorant
The remaining three cormorants of the Port Phillip Bay catchment are black on the upperparts with a white belly. The largest of these is the Pied Cormorant. It is found most often in saltwater habitats, although it can be seen in large, deep freshwater wetlands. Good places to look for this species are Jawbone Flora and Fauna Reserve and Ricketts Point in Beaumaris.
The Little Pied Cormorant
The smaller Little Pied Cormorant is more generalist in its habits. It is the familiar cormorant of farm dams and freshwater wetlands. However, it also occurs in sheltered bays and estuaries. Look for it at the Royal Botanic Gardens and at St Kilda Pier.
The Black-faced Cormorant
The last species is the Black-faced Cormorant. It is the most elusive cormorant in Port Phillip Bay. This species is typically found along rocky, wave-washed coasts. Locally, the best spots to see this species are Pope’s Eye and South Channel Fort in the middle of the Bay. These sites require a boat to get to. If boating isn’t your thing, the rocky shores of Point Lonsdale are probably your best chance of seeing this bird without venturing further afield to places like Phillip Island.
Written by Rowan Mott. Banner image courtesy of Rowan Mott.
Rowan is a Monash University PhD graduate and now works there as an ecologist. His research interests are broad, spanning seabird foraging ecology to plant invasions. When not in his office, he will most likely be in a woodland with binoculars around his neck and camera in hand.