Sunday, January 02, 2011

Waders: Bar-tailed Godwits and unBar-tailed Godwits!

A visit to the Sydney area in the northern winter is a good opportunity to get to grips with the 'baueri' race of Bar-tailed Godwit. The one we get in Malaysia most commonly is 'menzbieri', and the principal difference between them in the field is the back colour.

What do I mean by 'back'? Oddly enough, you only usually see the back of a wader when it is in flight. It's the bit above the rump, between the wings. In 'menzbieri' Bar-tailed Godwits, it's white, whereas, on 'baueri', it looks dark, owing to it being heavily barred. You can see the difference between the two, side by side, here.



The Entrance, about an hour north of Sydney, is a great place to get up close to waders as they're pretty used to people.



A small flock of three juveniles (the three front right) and two adults.



Bar-tailed Godwits are one of the easier waders to sex, as the bill length of the females is pretty consistently longer than the males (and they're visibly larger too). So this is an adult female.





While these are juvenile males.Interesting to note the difference in the amount of feather wear between these two birds.





Juveniles often don't have fully grown-bills. I wondered whether the lower bird might also be a female.



This was an interesting bird - an adult-type with barred rear flanks and some interesting patterns on the inner coverts (lesser, median and greater). Also, quite a range of feather ages, from very worn inner lesser coverts (or are they rear scapulars?), to moderately worn upper scaps, to very fresh lower scaps, tertials and inner primaries. I wondered whether it might be a 2nd year bird.



The birds would often move around the sandflats, giving me the chance to snap some in flight. Here's a juv, showing off that characteristic dark back.



Here's an adult. Take a look at the tail..





The central feathers are rather plain, and the outer webs of all but the outers have a strong greyish wash.







Quite different from the typically barred tails of juveniles.





This adult has an even less barred tail.



These two contravene the Trade Descriptions Act altogether!



You should be able to deduce that the bird on the far left is an adult and the one onm the far right is a juv.



So why are these called Bar-tailed Godwits?!

I have a few questions about these unbarred-tailed birds...

i) Is this a characteristic unique to adult non-breeding 'baueri' Barwits?
ii)Is the extent of 'unbarredness' related to age (ie the less barring the older the bird)?

If anyone can enlighten me I'd be much obliged!



So this would be a juvenile on the right and an adult on the left... no, wait!



It's a first winter Red Knot dropping in.







Briefly!



And a tattler. There's a slim chance of a Wandering Tattler down here, so I go over the salient features of Wandering...Dark upperparts? Well - it looks dark but the sky is overcast. Dusky flanks? Check. Supercilium poorly defined behind the eye? Check... Surely I can't be this lucky? Call? "Weee-wee-wee." Typical Grey-tailed, and completely unlike the trill of Wandering. Oh well, keep looking!

1 comment:

Choy Wai Mun said...

I'm really enjoying all your posts from Australia. Well done. Brings back good memories of my recent trip.