The race of Little Egret seen in Thailand is the nominate race, egretta
garzetta garzetta - notable for its completely yellow feet (as though it had
walked in yellow paint). The usual race seen in Australia is egretta
garzetta nigripes (sometimes immaculata).
The Asian nominate race does occur from time to time in Australia - usually
up north, but has been recorded elsewhere. Ruth and I saw one at the Western
Treatment plant on March 20th last year, and we posted information about our
sighting on birding-aus.
This sighting resulted in a little bit of email traffic, most notably from
Mike Carter where he pointed us to an article he had written in conjunction
with Peter Menkhorst and published in Australia Field Ornithology. I have
reproduced Mike's email in its entirety below, as I think it is valuable for
the information on distinguishing the races.
From: Mike Carter [mailto:pterodr...@bigpond.com]
Sent: Monday, 21 March 2011 4:51 PM
To: p...@angrybluecat.com; birding-...@lists.vicnet.net.au
Cc: Dave Torr
Subject: Re: [Birding-Aus] Little Egrets
Yes Paul, you're quite right about yellow-footed Little Egrets being of the
nominate Asian race - that is if there is yellow on the upperside of the
toes as well as the underside because as I'm sure you well know, adults of
the Australian race have greenish-yellow soles. In more extreme examples,
the birds appear to be wearing yellow booties on or to have walked in 2 cm
deep bright yellow paint!
This subspecies has previously been seen at the WTP Werribee, Victoria, and
at Darwin in the Northern Territory where they maintained a presence for
several years but I don't know the current situation there. For the first
Carter, M. & Menkhorst, P. (2006), 'Nominate Subspecies of the Little Egret
Egretta garzetta garzetta in Australian Territory', Australian Field
Ornithology, 23: 104-108. Unfortunately I don't have a pdf of this paper.
That paper has photographs that show the diagnostic features.
Note that these subspecies also differ in the loral pattern whilst both have
mostly black bills in adult plumage. In the Australian subspecies, the bare
skin of the lores extends from the eye to the forehead and is bright yellow
or orange. In the nominate race the loral pattern is less conspicuous
because the pale area is restricted to the upper loral region with the black
of the bill continuous through the gape almost to the eye. You should check
this to confirm that your bird is of the Asian form.
On the other side of Port Phillip Bay we too have been having an interesting
time with Egrets at the Eastern Treatment Plant. On 6 March we had our first
Intermediate Egret since March 2001 with the only other recent record nearby
being one in March 2006 at Edithvale. On that day we had two other Egrets
greatly different in size that confused us for a long while but which I now
believe were BOTH juvenile Little Egrets in spite of the size difference.
Furthermore, we had similar birds on two other nearby wetlands on Saturday
19 March. The bills on these birds are black distally but yellow on basal
half and some have black, not greenish-yellow soles. All the birds were
photographed and I have written detailed reports which will be sent to Dave
Torr with a view to placing them on the BOCA website. I suspect that they
may have bred locally so we are seeing unfamiliar, very young, birds.