Christmas Bells

Christmas Bells
Christmas Bells - Blandfordia nobilis

Wednesday, January 21, 2009

Fork-tailed Swifts appear over Robertson

These birds suddenly appeared over my house, two mornings ago. I knew straight away that they were Swifts, but I was not quite sure which Swift? The bird formerly called the "Spine-tailed Swift" (now officially the "White-throated Needletail") is the more usual species, south from Sydney. I have not seen many Swifts here, since moving to Robertson. I often look out for them before a summer thunderstorm, but have only seen them on a few occasions, over 6 years.

I should mention that all these images were taken from my back deck (so they qualify as birds from my backyard).

Click to enlarge the image. There are four swifts in the frame.
But, as I said, which Swift was I looking at?
The thing about Swifts is they fly so very, very fast (they get their name for a good reason). These birds were hawking at about twice the height of the local trees, and then circling higher, and swooping back down to just above the tree tops. Their speed and their circling was a real challenge, to try and track them. No autofocus job, this. I tried to monitor a bird as it flew away from me, then watched it come back, adjusting the focus , in an attempt to get a shot, as the bird raced back towards me.

Swift, at about 300 metres range.
(Shoalhaven Valley in distance)
The photographer's challenge is to focus on the distant bird,
then adjust focus as the bird comes zooming back
(they were circling constantly, for about 20 minutes).
Adjusting focus on a high speed bird is a great hit or miss experience.
My best shot.
For photographers, the speed settings was 1/1000th of a second.
Aperture F/5.6, with maximum zoom (300mm focal length).

This shows the elegant flight pattern of this species. Beautiful wings. The design is, of course, the sort of design aeronautical engineers can only dream about. The white rump is diagnostic (to distinguish it from the White-throated Needletail, which has a white throat and white undertail coverts, but the rump is brown).
I wish to acknowledge the assistance of Geoffrey Dabb (of COG) in confirming my ID of these birds as the Fork-tailed Swift (Apus pacificus) (a species I had not seen before).
I like this image - it shows the colour of the upper parts of the bird, and wings, plus the white rump. The wing shape, as it curves around, while diving, is very elegant.
A blurry image, but it does show the long tail, clearly forked.
High speed shot of a passing, zooming Fork-tailed Swift.This one is gliding away from me, at high speed.
This blurred image shows the Fork-tailed Swift with tail in full spread (a deep "V").
Almost certainly this bird is using its wings and tail for full control as it strikes at an insect.

A composite image (5 frames) of Fork-tailed Swifts,
showing the changes in wing shape and profile, as the birds tumble, zoom and soar.
Click to enlarge

Fork-tailed Swift with another species of bird. But which other bird?

This next image had me thinking Tree Martin,*** but on reflection, the bird in the image (relative to the Swift) is larger than a Tree Martin would be, and, as there was a hot north-westerly blowing, on which all these birds had travelled in, it is entirely possible that it is a White-breasted Woodwallow. Woodswallows are known to move about on favourable winds, following swarms of insects. Even the shape of the wings is "right" for a Woodswallow, (and wrong for aTree Martin), now that I think more about it. *** I have since decided that this is sufficiently unlikely to be a White-breasted Woodswallow, that I cannot "claim" that species. It is more likely to be a Tree Martin. The photo is not good enough for a positive ID, one way or the other.


mick said...

That is indeed a "Wow!" post and photos. I've been watching Fairy Martins as they swoop around the yard and thinking they were impossible to photograph - but obviously not with more experience and practice!

Tyto Tony said...

Hi Denis

Tough getting those birds in flight pictures. But a mere $5000 or so buys a 45-point AF Canon 1DII. Treble it for fast 500mm lens and you're almost there! After all, kindly Kev insists we spend, spend, spend ;-)

Snail said...

Just getting them in frame is a great achievement, let alone getting them in focus!

Swifts are rather special birds. We occasionally get needletails on campus --- they remind me of small, zippy falcons.

Denis Wilson said...

Hi Mick, Snail and Tony.
Thanks everybody.
Mick, I messed up the speed details on the images. 1/1000th of a second shutter speed, not 1/100 as I had originally posted. I have corrected the record.
Tony. Thanks for the suggestion. Unfortunatley, I am not on Kindly Kev's present list. Not a pensioner, no dependent kids (I have one who is offically not dependent, but doesn't realise it).
Sounds nice, though.
Its the lens I could do with, most of all (or the Nikon equivalent), but I dream on .....

Snail, They are wonderful to watch when flying - and as you say, their wings are very like Falcons.

Duncan said...

You did well Denis. It's a bird I haven't seen down here, only W T Needletails

Lynn said...

This is all very interesting - I had been watching these birds and wasn't sure what they were.. falcons? had come into my mind.

Denis Wilson said...

Hi Lynn
They look a bit like (small) falcons, with the wings swept back like that. But they "hawk" for insects on the wing, and go round and round, whereas Falcons seldom do that. Also, they travel in groups, whereas Falcons seldom travel in more than pairs, usually solitary.
I'm glad you saw some over your side of Robertson too.
I posted an article on the Canberra bird forum, expecting other reports from people on the South Coast, but no other mention of them, so far.

Lynn said...

Yes. Also the swift (compared to the falcon) seems to have a more rapid wing beat.... Is this right?

Denis Wilson said...

Hi Lynn
Yes. They sometimes hold their wings almost straight out, and seem to be able to flap the tips very fast indeed.
But it is the fact that they are hunting insects, and hence flying and swerving and diving and circling, that really distinguishes them. Peregrine Falcons will sometimes fly up and down a valley, to terrorise birds like Rosellas, and try to panic them into flight. But they are many times larger, and very heavy in the body compared to these guys.
Although Swifts do look falcon-like, you would never mistake a Falcon for a Swift when you see one.