Monday, 4 October 2010

Azores egret: opinions sought

Extensive yellow on the legs and apparently yellow-tinted lores suggest
this egret on Terceira could be a juvenile Snowy. But it's complicated ...


It’s post-trip catch-up time, and first on the to-do list is this egret from Praia da Vitoria, Terceira. I found the bird while scanning from the cliff road to the north of the harbour – the view is expansive from this vantage point, and the first time I looked from here, in late winter 2008, I picked up a Laughing Gull. So now I always try to make the time to see what might be on view.

Note how the yellow extends to the tibia, a character of Snowy Egret
but not conventional wisdom for Little Egret of any age.
This bird was photographed with a Canon 500 mm f4 lens, 1.4x EF II
extender and EOS 50D with built-in 1.6x effective magnification. Even
so, images are still very small, and reproduced here at 100 per cent
(but with large areas of extraneous background cropped out).
These photos were taken on 30 September 2010. At the time there were two egrets feeding along the inner edge of the north harbour wall, though not together. The closer bird was a Little Egret, the expected white egret throughout the archipelago, but the more distant bird immediately stood out because of the obvious yellow coloration on its legs. The extent of yellow on not only the tarsi but also on the knees and tibia (mainly on the back and 'insides') strongly suggests Snowy, as does what I perceive to be a hint of yellow-green on the lores.

It is often suggested in the literature that young Littles can have more extensively yellow legs than adults, but it seems to be restricted to the lower tarsi and rarely, if ever, reaches the knee joint; eg Pyle 2008 says of Little that it has the "dorsal side of tarsus blackish or with reduced amount of yellowish extending partially up tarsus in HYs … vs legs extensively greenish yellow [in Snowy] including most or all of tarsus and part of tibia in HYs and some AHYs”. On the Azores bird, particularly in the rear view shot, the extent of greenish-yellow on the legs can be easily appreciated.

Little Egret for comparison: photographed at the same site on the same
day, this bird was somewhat closer (both were inside a Portuguese naval

base, from where I was ejected when trying to get closer images).
On this basis alone this bird would be a Snowy, but the colour of the lores seems to support the ID too. Depending on what you read, it could be said that there is overlap in the loral colour of young egrets of these two species, though personally I've never seen any juvenile Littles with detectably yellow lores; on the other hand, there are photos of juvenile Snowies with far brighter yellow lores than here. The Azores bird seems to be a youngster as there is a suggestion of a pale underside to the bill in the rear view shot; if it was a Snowy it could only be a juvenile, as the lores fairly quickly ‘colour up’ to an adult-like brighter yellow in the first autumn.

This shot shows the sole of the left foot on the putative Snowy; it seems
a similar shade of yellow to the upperside, not duller as is often the
case in Little Egret (see Pyle 2008).

It's also worth knowing that there is a history of controversial egrets in the islands, as addressed by Staffan Rodebrand in some detail on the Birding Azores website (www.birdingazores.com/?page=egret). Perhaps some of these debated birds are juvenile Snowy Egrets, which are surely more likely to occur than hybrids or ‘variants’ (and given that Little Egret has not been proved breeding in the archipelago, mixed pairings seem highly unlikely to me; indeed, according to Pyle they are unproven anywhere).

The likelihood, then, is that this is a juvenile Snowy Egret. But are all the features shown fully compatible with juvenile Snowy, especially the lores? And can known juvenile Little Egret ever approach this bird in appearance? How about structural differences, which may be apparent (just) in these images too? Comments are welcome, especially from those with extensive field experience of juvenile Snowy Egrets.

Thanks to Peter Alfrey for his earlier comments on this bird and for providing additional references, and also to Gerbrand Michielsen.

Praia da Vitoria harbour, Terceira: egret watchpoint.
References
Grant, P J, Hume, R A, King, B, Payne, R, Russell, W, and Wheeler, C E. Bare-part colour of Snowy and Little Egrets. British Birds 73: 39-40.
Massiah, E. 1996. Identification of Snowy Egret and Little Egret. Birding World 9: 434-444.
Pyle, P. 2008. Identification Guide to North American Birds. Part II. Slate Creek Press, California.
http://www.birdingazores.com/?page=egret
http://www.oceanwanderers.com/LTEGRT.html
http://www.martinreid.com/Main%20website/egrets4.html
http://www.martinreid.com/Main%20website/egrets.htmlhttp://secrb.trinidadbirding.com/idlittlesnowyegret.html

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