Thursday, July 21, 2011

Thank Goodness for Auto-focus

About a month ago, I received an email telling me about a sighting of 4 Crested Grebe at Orielton Lagoon, seen during the annual winter gull count conducted by Birds Tasmania. The note mentioned 2 adults, an immature and a juvenile. The latter quite unusual here. Crested Grebe are not that common in Tasmania, with most sightings from Lake Dulverton, the Derwent River in the Granton area and at Orielton Lagoon. At times, at the latter site, they have numbered up to 40 or more, but in recent times, they have been conspicuous by their absence.
I've found that early morning on still days is the best, or at least the easiest time to look for ducks and grebes at this venue. As luck would have it, the day following receipt of the email, was ideal if cool (around freezing point) and I set forth.
Early morning on Sorell causeway is not the ideal birding spot, with the commuter traffic whistling past, but fortunately there's a 'lay-by' mid way from which much of the lagoon can be scanned. (Watching from within your vehicle is a good option here). A quick look suggested that there wasn't much about, save for several Musk Duck and a raft of Hoary-headed Grebe, numbering perhaps a dozen. The numbers of both the Crested and Hoaryheads have been low recently, and I suspect that the high Mainland rainfall is to blame. The numbers of grebes and also the Eurasian Coot seen in Tasmania, fluctuate widely, and they only breed here in small numbers, so it's reasonable to assume that most are Mainland bred birds. When I first came to Tasmania, over 40 years ago, I didn't see a single Coot for over 2 years, and this puzzled me as Sharland's Tasmanian Birds declared it to be "generally common". But when they did appear they were 'everywhere', with some flocks in the Derwent River consisting of over a thousand birds.
A visual sweep of the lagoon showed no sign of the Crested Grebes. Alongside where I had parked, a single male Musk Duck was diving for food. I haven't had much luck trying to photograph this species, not that they rate highly on my "must do" list, so I thought I'd give it a go.

I've been waiting for minor eye surgery, as luck would have it, on my "good" eye, the right--I can't actually see whether the image is in focus or not, something of a handicap using a telephoto lens. The low angle light didn't help photographing an all black bird either. Well as you can see from the accompanying images, I did manage a few shots, nothing to write home about, but definitely thanks to the benefits of auto-focus. One of the images shows the duck eating a crab, and in the several dives that I witnessed, crabs were obviously the food of choice. I'm not sure what I thought Musk Duck's diet is, but I didn't expect it to include crabs. Literature suggests aquatic insects, but also crayfish, so perhaps crabs aren't that unusual. The lower shot taken as the bird dived, shows the stiff tail, peculiar to both this species and also Blue-billed Duck.
Later views of the lagoon suggested that the sought after Crested Grebes had moved on, but it's often worth a look as you cross this causeway.
[I've had my eye surgery and I can "see" again, what a difference!]

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