White-winged Tern (Chlidonias leucopterus) by Ian

Newsletter – 4/25/2010

The weather is improving here, so I went birding a couple of times last week. The first time I went to Hodel Road, Giru, just south of Townsville, which goes through an area of marshy coastal grassland that can turn up interesting birds. At this time of the year, it can be good for White-winged (Black) Terns starting the migration back to the northern hemisphere and some, like the one in the first photo, may be in the unmistakable breeding plumage, with black bodies and pale wings. I’ve bracketed (Black) as this qualifier is usually added in Australia, while Birdlife International calls it just ‘White-winged Tern’.

More usually in Australia, we see White-winged Black Terns in non-breeding plumage – like the one in the second photo – and care needs to be taken to distinguish them from the related, slightly larger, Whiskered Tern in the same plumage. Perhaps the best field mark is the shape of the black band on the head. In the White-winged Tern it forms a vertical hoop over the crown of the head; in the Whiskered Tern it forms a horizontal hoop around the nape and the crown is whitish. There are also differences in the patterns of the upper wing. In the White-winged the dark leading edge (visible in the second photo) and the whitish rump gives the bird a patchier appearance than that of the more homogeneous Whiskered.

White-winged Tern (Chlidonias leucopterus) by Ian

Some points that may be of interested to bird photographers relate to birds in flight coming towards the camera and to backgrounds. Telephoto lenses have very a shallow field of view, particularly at the high shutter speed/large aperture combination necessary to freeze the motion of the bird. This means that even if the auto-focus has operated correctly, the bird may have moved out of focus during the lag while the photo is taken. Some cameras have an autofocus option to compensate for constant movement, called ‘AI-Servo’ on Canon SLRs, and this is the occasion to use it.

The problem with backgrounds is that the autofocus may miss the bird and grab the background instead. Birds against the sky are easier than against the ground – unless there are clouds with high contrast. Practicing tracking birds in flight is the solution here, and I use a single focus point in the centre of the viewfinder. This gives much more control over auto-focusing and not only with birds in flight but also in spatially complex shots such as a bird in a tree with branches around it.

On the website, I’ve been experimenting with changes to the layout of bird photos. The changes involve technical aspects such as getting rid of frames, but the advantages from a user’s point of view include being able to bookmark individual photos (rather than just species), and scroll bars to prevent thumbnails extending way below the window. If you’re interested, have a look at http://www.birdway.com.au/otididae/australian_bustard/source/australian_bustard_99577.htm – I’d welcome your feedback.

The other birding outing last week was to get photos of nesting Chowchillas at Paluma (this gallery uses the new layout and has 600px-wide images instead of 500)

Best wishes,
Ian
—
Ian Montgomery, Birdway Pty Ltd,
454 Forestry Road, Bluewater, Qld 4818
Phone: +61-7 4751 3115 begin_of_the_skype_highlighting              +61-7 4751 3115      end_of_the_skype_highlighting
Preferred Email: ian@birdway.com.au
Website: http://birdway.com.au

Lee’s Addition:

The White-winged (Black) Tern is in the Laridae Family of the Charadriiformes Order. There are 102 members of the family. Only 39 of those are Terns, the rest are Gulls, Noddy, Skimmers, and Kittiwakes. They are small terns generally found in or near bodies of fresh water across from Southeastern Europe east to Australia.

Their behavior like the other “marsh” terns (Chlidonias), and unlike the “white” (Sterna) terns, these birds do not dive for fish, but fly slowly over the water to surface-pick items on the surface and catch insects in flight. They mainly eat insects and small fish. In flight, the build appears thick-set. The wing-beats are shallow and leisurely.

Their breeding habitat is freshwater marshes across from southeast Europe to central Asia. They usually nest either on floating vegetation in a marsh or on the ground very close to water, laying 2-4 eggs in a nest built of small reed stems and other vegetation. In winter, they migrate to Africa, southern Asia and Australia. It is a scarce vagrant in North America, mainly on the Atlantic coast, but a few records on the Pacific coast and inland in the Great Lakes area.

The White-winged (Black) Tern is another of the neatly created birds which shows the Handiwork of God.

Then God said, “Let the waters abound with an abundance of living creatures, and let birds fly above the earth across the face of the firmament of the heavens.” (Genesis 1:20 NKJV)