cywong

Po Toi, 21/04/09

Thanks to Geoff for leading us to watch this Frigatebird.

yyattung

Thanks for posting the photo.

This frigatebird does not show white spur on underwing auxillaries. Is it really a Lesser Frigatebird?

Also, the white belly patch goes down to the position of feet. I am thinking it would be a Christmas Frigatebird.

cywong

Thank you for correcting the I.D.

You are right; juvenile Lesser Frigatebirds should have white armpit spurs.

I think Geoff will post some better photos that show this bird more clearly.

lpaul

I think this is a Great Frigatebird; there is no white on the auxillaries, the breast band is very broad and the belly patch is square ended and stops short of the feet.  I think these features when combined eliminate Christmas Island FB.

However, I do not have the excellent paper that was BirdingAsia to hand so will need to check that to be sure!

wgeoff

Here are two larger photos of this Frigatebird.




As you can see, the bird does have white spurs going under the wing although they do not show well on Cherry's longer range photos. The white belly patch extends to beyond the legs although it is not obviously pointed.

According to the diagrams on page 136 of the HKBWS 1998 Bird Report, this is more like a Christmas Island Frigatebird as suggested by Tung.

tmichael

After referring to a few sources, notably the article "Identification of Christmas Island, Great and Lesser Frigatebirds" by David James in Birding Asia No. 1 (June 2004), I can't see why this isn't a juvenile Lesser Frigatebird.

It very closely resembles his Plate 30 bird, labelled juvenile Lesser, having, to quote his caption to that photo, "prominent axillary spurs originating from the front corners of an almost triangular white belly-patch (the belly patch appears more triangular when viewed from directly below)" [as indeed it does in the first distant shot from below].

Having said that his Plate 22, showing juvenile Christmas Island does not look massively different - except perhaps for the breadth and solidity of the breast-band - nor do some of the photos of Christmas Island juvenile in the Chalmers paper. There again the picture of a bird identified as a Lesser Frigatebird, that I saw at Mai Po on 17 March 2001, photographed by John Holmes and also shown in the Chalmers paper, looks similar too.

With no real way of judging size, are they, I wonder, separable with any kind of certainty, even with good photos like this, and isn't it interesting how the clearly present spurs on this recent Po Toi bird "disappeared" on the more distant shot?

Mike Turnbull

[ Last edited by tmichael at 23/04/2009 19:02 ]

kmike

The best way to judge size is for Geoff (or even better, me) to see it again next to a Black Kite . . .  he said hopefully!  

Bigger its Christmas, smaller its Lesser.

happy to be disagreed with.

Cheers
Mike K

wgeoff

Always willing to oblige.

Here are 4 sequential photos of an aerial battle between this bird and a Black Kite.
The Black Kite started it but the Frigatebird easily out-manouevered it and the Kite finished up at the business end of a rather vicious looking beak.




To get back to the subject of identification.

I originally identified this bird as a Lesser because of size (slightly longer wing-span than Black Kite) and the white spurs. However, Tung's comment led me to look at the Frigatebird Id Guide by Mike Chalmers in the 1998 HKBWS Annual Report and the diagrams of the white belly patches on page 136 do indicate this could be a Christmas Island. According to this, the breast band on a Lesser should be narrower and the white patch should end before the legs, not after. I don't have the Birding Asia reference.

However, having compared the white patch on this bird with the previous two frigatebirds I have seen on Po Toi, which were both accepted as Lesser, they are very similar. All have a broad breast band and the white patch finishes between the legs on them all. Since I don't think they are all Christmas Island, I will stay with my original identification of Lesser Frigatebird for this one and all the previous birds, unless someone tells me otherwise.

[ Last edited by wgeoff at 24/04/2009 06:19 ]

yyattung

I agree with Geoff that it is a Lesser Frigatebird now.

The first pictures show the distant view of the bird which does not have the white spur, but later photos could show this feature and size with the Black Kites, indicating that should be a Lesser.

cmichaell

Wow! Have just caught up with this string. Good to see so much interest in frigatebird id!

I have no doubt that this is a first stage [=juvenile] Lesser Frigatebird, as originally identifed by Geoff and concluded by Tung.

The diagnostic feature is the white axillary spurs leading forward from the front edge of the more or less triangular white underparts. In Christmas Island the spurs would be set further back and the white patch would be more diamond or oval-shaped. In addition the bill is not long enough for a Christmas but just right for Lesser. With the extra pics showing it scrapping with the Black Kite, it can also be seen to be not that much bigger and certainly not as large as a Christmas or Great would be in direct comparison. Lastly, the alar bar [the pale area across the upperwing coverts] is not particular conspicuous or well marked. That is just right for Lesser whereas Christmas would be much paler and more extensive.

Mike Chalmers

cywong

Sorry for posting such a poor quality photo and causing so much confusion about the identity of this frigatebird. Luckily, we have a very constructive discussion; and through the input from bird experts, we learn more about identification of frigatebirds.