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Birds

Darter Retrieval.

The Australasian Darter (Anhinga novaehollandiae) is sometimes mistaken for a type of cormorant. The two species are often found together as they share the same criteria for their fishing spots – smooth, open waters, with plenty of overhanging branches, rocks or posts on the fringe, to perch on and dry their plumage between fishing trips.

The Darter is distinguished by its long snake-like neck, and its longer, straight bill, without the terminal hook of the cormorant, with which it spears fish.

It is found all over Australia, except for the driest parts of South Australia, Northern Territory and Western Australia. It is an occasional vagrant in Tasmania.
Darters are unaffected by salinity, and can sometimes be found fishing near the shore on ocean beaches when conditions are calm enough.

Like many fishing birds, the Darter has a series of serrations on its bill close to the head. These help with grip on wet, slippery fish. Occasionally though, human rubbish, particularly plastics, can get caught on them. We can’t really tell from this next photo – we suppose it might be a fish-bone – but this guy may have one of those nylon tags used on clothing labels caught in his bill.

It is sometimes suggested that the reason cormorants and darters need to dry their plumage in the sun is because they do not have the same oil-secreting glands that other aquatic birds have. This seems to be a fallacy – they do have these glands, just above the tail as with other water birds.
This darter seemed to be starting each preen from a point just above his tail, and I think this next photo shows the gland.
Current theories that we’ve read suggest that cormorants and darters have evolved an oil that is not as water-resistant as other birds’ because of the way they hunt. Truly water-resistant plumage traps a lot of air, making the bird more buoyant. For birds that chase or stalk their prey beneath the water, less buoyancy is an advantage. The price of that is having to drip-dry the wings.

After a while, he decided he need more sustenance, and resumed his search for fish. Darters are even less buoyant than cormorants, and the sit much lower in the water – usually only the neck and head is visible above the waterline. They can dive to 60 or 70 centimetres deep, and it is said that underwater they don’t so much chase their prey as stalk it.

It was not long before this guy had speared a catch. Depending on the size of their catch, a Darter will often bring it into land to eat (see “Seafood Brunch” 24 January 2021). Very small fish are often eaten underwater (or so we have read), and medium-sized fish can be flipped into the air and swallowed on the water. I think our Darter was in two minds about this fish: he first seemed to be making for land…

…but then, either changed his mind, or the fish wriggled a little too much. In any case, he fumbled his meal, and had to resort to a full-stretch diving catch to regain it. After that, he promptly ate it before any other unfortunate accidents.

After his elevenses, he headed back to his original rock to once again dry himself off with some vigorous flapping.

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