Thursday, July 12, 2007

Bird of the Day: Western Reef-Heron

The birding listserves are alive with chatter, and people are descending on Brooklyn for a rare bird: a Western Reef-Heron (Egretta gularis) from coastal West Africa. I dearly wish I could go see this bird, but research, and prior weekend plans have me tied to upstate NY for the time being. If it sticks around for a while (and past sightings suggest it will), then I may yet get my chance.

This bird has occurred in North America only a handful of times. In an email from NYSbirds-l (due to lack of a long-term archive, I'm copying recent emails from the short-term archive, birdingonthe.net), Angus Wilson summarizes past sightings:

Subject: RE: W. Reef-Heron Kudos
From: "Angus Wilson"
Date: Wed, 11 Jul 2007 15:27:16 -0400
Hi All,

I happened to be compiling a list of previous sightings to see if I could
discern any patterns and also look at plumage details to see if meaningful
statements can be made about the number of birds involved. It is quite
possible that the sightings up and down the coast in 2005, 2006 and 2007
have involved the same bird. Way back to 1983 is more of a stretch. I have
not yet looked into the sightings from the Caribbean, the presumed source of
this bird and possibly its wintering area. One obvious revelation is that
the bird has lingered for extended periods in certain chosen spots. Whether
Brooklyn will be that spot in 2007 is unknowable at this point but so far
things are looking favorable. I would be delighted to receive additional
dates or corrections to this hastily acquired list.

** 1983 **
[Nantucket Island], Massachusetts, April 26 � September 13th, 1983.

** 2005 **
Stephenville Crossing, Newfoundland, most of summer until early Sept. 2005.

** 2006 **
Glace Bay, Cape Breton, Nova Scotia, 26 June - 2 Aug 2006 (possibly from
May).
Rye Harbor, New Hampshire, early August 2006.
Kittery, Maine, August 18, 2006.
New Castle, New Hampshire, August 19-30, 2006.

** 2007 **
South Amboy, New Jersey, June 30, 2007.
Brooklyn, New York, July 8 2007.


It also occurs more regularly in the Caribbean.

Pictures are available from Lloyd Spitalnik, Alex Wilson, and Brendan Fogerty.

Finally, this bird is of interest to me because it is taxonomically ambiguous - it is part of a complex of species with Little Egret, Snowy Egret, Dimorphic Egret, and others, all of which have at some points been considered conspecific with Little Egret (Egretta garzetta) of Europe. Here are several NYSBirds-l posts that highlight the taxonomic discussion:

Subject: Western Reef Heron taxonomy
From: Rob Jett
Date: Tue, 10 Jul 2007 06:57:22 -0400
Yesterday morning Sean Sime and I went to Coney Island Creek to look
for the reported Western Reef Heron. As others have posted, the bird
was present and we had great looks as it fed in the shallow creek.
I'll have some photos and a short video posted on my blog later this
morning.

I'm writing now because, on the way home, Sean and I were wondering
about the range, behavior and other data unknown to either of us.
Anyway, a search of the Internet turned up some interesting
information, particularly a discussion on the taxonomy and
relationship between the Little Egret and the Western Reef Heron. I
found the following on the the "Frontiers of Birding Identification"
forum and thought that others might find it interesting and
enlightening. Some subscribers may have already seen part of this
thread on the NJ list. I suppose the subspecies relationship's will
become more clear in the near future, but I'll still be confused ;-)

* * * * * * * * * *

The Newfoundland, Nova Scotia, and New England W Reef-Heron Author:
Ian A. McLaren Date: 08-24-06 09:34

All:

Our meanderings are somewhat straightened out by a very informative
current posting on NJ Birds by Nikolas Haass (forwarded to me by Don
Stokes), which can be accessed by Google I assume, but this may work.

http://birdingonthe.net/mailinglists/NJBD.html#1156423365

Of particular relevance is his reference to the late Andreas Helbig's
work in Bauer et al. 2005, to wit:

"The late Andreas Helbig (he is the one who split European Larus
argentatus and American Herring Gull L. smithsonianus) summarized his
work in Bauer et al. (2005): The Western (Atlantic) form of Western
Reef Heron Egretta [garzetta] garzetta gularis seems to be a southern
SUBSPECIES of LITTLE EGRET Egretta [garzetta] garzetta. Similar to
Snow Goose and 'Blue Goose' which originally were geographically
separate populations of the same species, the southern subspecies of
Little Egret (gularis) occurs predominantly in the dark morph. In
contrast, the Eastern (Indian Ocean) form of Western Reef Heron
Egretta schistacea (formerly Egretta gularis schistacea) seems
neither closely related to Little Egret nor to 'Western' Western Reef
Heron (better 'Southern' Little Egret, this name is my personal
input), but seems to be a different species and NOT even a member of
the superspecies Egretta [garzetta]! On the other hand the Madagaskar
form Egretta [garzetta] dimorpha might be a separate species within
the superspecies Egretta [garzetta]!

A German summary of all that will be found in HAASS (in press) and a
summarizing German ID paper to all the confusing egrets has been
published in Limicola (HAASS 1997)."

[References to above]

BAUER, H.G., E. BEZZEL & W. FIEDLER (2005): Das Kompendium der V? gel
Mitteleuropas. - Wiebelsheim (Aula).

HAASS, N.K. (in press): Egretta gularis Bosc, 1792. K? stenreiher.
In: H? LZINGER, J. (in press): Die V? gel Baden-W? rttenbergs 2.1. -
Stuttgart.

________________________________________________________________________

Hello,

Nikolas Haass asked me to cross-post his notes and references from
Jerseybirds. If you respond, please CC: him since he doesn't
subscribe to Frontiers.

Thanks, Laurie Larson Princeton, NJ -------------------\----------

Date: Sat, 19 Aug 2006 20:20:05 -0700 Reply-To: Nikolas Haass
Sender: New Jersey Birding
From: Nikolas Haass
Subject: OL comment on Western Reef Heron taxonomy

The taxonomy of Little Egret and Western Reef Heron has been changing
a lot and treated differently in the leading literature. However,
according to the most modern taxonomy there might be an upcoming
complicated combination of lumps AND splits (unfortunately only a
lump for the AOU/ABA area) :

The Western (Atlantic) form of Western Reef Heron Egretta [garzetta]
garzetta gularis seems to be a southern SUBSPECIES of LITTLE EGRET
Egretta [garzetta] garzetta. Similar to Snow Goose and 'Blue Goose'
which originally were geographically separate populations of the same
species, the southern subspecies of Little Egret (gularis) occurs
predominantly in the dark morph.

In contrast, the Eastern (Indian Ocean) form of Western Reef Heron
Egretta schistacea (formerly Egretta gularis schistacea) seems
neither closely related to Little Egret nor to 'Western' Western Reef
Heron (better 'Southern' Little Egret), but seeems to be a different
species and NOT even a member of the superspecies Egretta [garzetta]!

On the other hand the Madagaskar form Egretta [garzetta] dimorpha
might be a separate species within the superspecies Egretta [garzetta]!

Of course Eastern Reef Heron Egretta sacra remains a different species.

Nikolas ---------------- Nikolas Haass nhaass AT yahoo.com Philadelphia, PA

Date: Thu, 24 Aug 2006 05:39:48 -0700 Reply-To: Nikolas Haass
Sender: New Jersey Birding
From: Nikolas Haass
Subject: Re: Western Reef-Heron

Firstly, I don't have any doubts about the ID of the Maine bird. I
think it is a 'Western Western Reef Heron', which I called 'Southern
Little Egret' below. Interestingly Eastern Western Reef Heron is
commonly kept in captivity and thus a frequent escapee. Western
Western Reef Heron seems not to be that common in captivity. Thus,
the bird might even be a 'wild' bird! However, they are no long
distance migrants... But I don't want to discuss that, I'd rather
wanted to give more information or confusion concerning the taxonomy:

More details of the Western Reef Heron taxonomy: gularis (Bosc,
1792), breeds at the West African coast, schistacea (Hemprich &
Ehrenberg, 1828) breeds at the Indian Ocean coast, dimorpha (Hartert
1914) breeds on islands in the Indian Ocean (CRAMP & SIMMONS 1977;
HANCOCK & KUSHLAN 1984; DEL HOYO et al. 1992).

BAUER & GLUTZ VON BLOTZHEIM (1966) ; PAYNE & RISLEY (1976) ; CRAMP &
SIMMONS (1977) ; PAYNE (1979) treat Western Reef Heron as a separate
species.

HANCOCK & KUSHLAN (1984), DEL HOYO et al. (1992) however, treat all
forms of Western Reef Heron as subspecies of Little Egret: Egretta
garzetta gularis, Egretta garzetta schistacea und Egretta garzetta
dimorpha.

VOISIN (1991) treats Dimorphic Heron Egretta gularis dimorpha as
subspecies of Western Reef Heron.

BAUER & GLUTZ VON BLOTZHEIM (1966) ; CRAMP & SIMMONS (1977) treat
Dimorphic Egret Heron Egretta gularis dimorpha as subspecies of
Little Egret Egretta garzetta dimorpha (although they treat Western
Reef Heron as a separate species: E. gularis gularis and E. gularis
schistacea)

PAYNE & RISLEY 1976; PAYNE 1979 treat Dimorphic Egret as a separate
species: Egretta dimorpha.

WOLTERS (1976) treats the Eastern form of Western Reef Heron as
separate species: Egretta schistacea.

The late Andreas Helbig (he is the one who split European Larus
argentatus and American Herring Gull L. smithsonianus) summarized his
work in Bauer et al. (2005) :

The Western (Atlantic) form of Western Reef Heron Egretta [garzetta]
garzetta gularis seems to be a southern SUBSPECIES of LITTLE EGRET
Egretta [garzetta] garzetta. Similar to Snow Goose and 'Blue Goose'
which originally were geographically separate populations of the same
species, the southern subspecies of Little Egret (gularis) occurs
predominantly in the dark morph.

In contrast, the Eastern (Indian Ocean) form of Western Reef Heron
Egretta schistacea (formerly Egretta gularis schistacea) seems
neither closely related to Little Egret nor to 'Western' Western Reef
Heron (better 'Southern' Little Egret, this name is my personal
input), but seems to be a different species and NOT even a member of
the superspecies Egretta [garzetta]!

On the other hand the Madagaskar form Egretta [garzetta] dimorpha
might be a separate species within the superspecies Egretta [garzetta]!

A German summary of all that will be found in HAASS (in press) and a
summarizing German ID paper to all the confusing egrets has been
published in Limicola (HAASS 1997).

BAUER, K.M. & U. N. GLUTZ VON BLOTZHEIM (1966): Handbuch der V? gel
Mitteleuropas. Bd. 1. - Frankfurt am Main. BAUER, H.G., E. BEZZEL &
W. FIEDLER (2005): Das Kompendium der V? gel Mitteleuropas. -
Wiebelsheim (Aula). CRAMP, S. & K. E.L. SIMMONS (1977): Handbook of
the Birds of Europe, the Middle East and North Africa. The Birds of
the Western Palearctic. Vol. 1: Ostrich to Ducks. - Oxford, London,
New York (Oxford University Press). HANCOCK, J. & J. KUSHLAN (1984):
The Herons Handbook. Paintings by R. GILLMOR & P. HAYMAN. - London &
Sydney (Croom Helm). HAASS, N.K. (1997): R? tselvogel 62: K?
stenreiher Egretta gularis. Limicola 11: 310-311. HAASS, N.K. (in
press): Egretta gularis Bosc, 1792. K? stenreiher. In: H? LZINGER, J.
(in press): Die V? gel Baden-W? rttenbergs 2.1. - Stuttgart. HOYO, J.
DEL, A. ELLIOTT & J. SARGATAL (1992): Handbook of the Birds of the
World. Vol. 1: Ostrich to Ducks. - Barcelona (Lynx Edicions). PAYNE,
R.B. (1979): Ardeidae. In MAYR & COTTERELL (eds.). Peter? s Check
List of the Birds of the World (2nd ed.). Mus. Comp. Zool.,
Cambridge, Mass. PAYNE, R.B. & C. J. RISLEY (1976): Systematics and
evolutionary relationships among the herons (Ardeidae). Univ. Mich.
Mus. Zool. Misc. Publ. No. 150. VOISIN, C. (1991): The Herons of
Europe. London (T & AD Poyser). WOLTERS, H.E. (1975-1982): Die
Vogelarten der Erde. - Hamburg und Berlin (Parey).

Nikolas ---------------- Nikolas Haass nhaass AT yahoo.com Philadelphia, PA Subject: Re: Western Reef Heron taxonomy
From: "Shaibal Mitra"
Date: Tue, 10 Jul 2007 16:21:15 -0400One thing that seems relatively straightforward in all the complexity surrounding
the Egretta garzetta superspecies (which traditionally includes our own Snowy
Egret, in addition to various Little Egrets and Western Reef-Herons) is that the dark
egrets identified as Western Reef-Herons on Barbados, Long Island, Nantucket,
Maine/New Hampshire, Nova Scotia, and Newfoundland belong to the coastal West
African taxon gularis. This taxon is dimorphic, having white and dark morphs, and
differs from garzetta Little Egrets in several respects, including ecology, soft parts
coloration, and the relative proportions of the bill, tibio-tarsus, and tarso-
metatarsus. Whether gularis ought to be treated as its own species (seems likely to
me), as a subspecies along with garzetta in a polytypic Little Egret (not totally
implausible), or as part of a broader polytypic species including the coastal Indian
Ocean taxon schistacea (highly implausible, though currently the official stance of
most authorities!)—the dark birds seen in North America appear to be perfectly
fine examples of dark morph gularis.

The notion of “dark morph Little Egrets” seems to me something of an ineradicable
medusa, in that some people use this term when referring to things that could be
described much more precisely as “dark morph gularis” or “dark morph schistacea”
—whereas others use it in an entirely vague way. To my knowledge, among the
highly migratory, northern breeding populations of garzetta (strict sense Little
Egrets), dark morph individuals are essentially unknown, and some of the very few
examples cited from time to time might actually have been vagrant individuals
properly referable to gularis or schistacea.

Thus, the question that ought to be haunting North American listers is not “Is my
Western Reef-Heron really a Little Egret?”—but rather, “Can I be sure that my North
American Little Egret was not actually a white morph gularis Western Reef-Heron?”
Dig out those field notes and check out the relative lengths of those tibio-tarsi and
tarso-metatarsi!

Shai Mitra
Bay Shore, NY
Subject: gularis vs. garzetta
From: "Shaibal Mitra"
Date: Tue, 10 Jul 2007 19:22:00 -0400Several people have inquired about details concerning the ways in which gularis
Western Reef-Herons differ from gularis Little Egrets.

Among the sources I have at hand, the following three contain the most useful
information concerning differences between nominate Western Reef-Heron (Egretta
[garzetta] gularis gularis) and nominate Little Egret (Egretta [garzetta] garzetta
garzetta).

Beaman, M. & Steve Madge. 1998. The handbook of bird identification for Europe
and the Western Palearctic. Princeton University Press.
This source is extremely useful for many species that also occur in North America
and is recommended for serious American birders. It contains the most
sophisticated analysis of identification criteria for gularis vs. garzetta. I’ve
copied
the pertinent portions here, but omitted statements referring to the rather
dissimilar taxon schistacea.

“Dark morph and intermediates unlikely to be confused [with other species] in
normal circumstances (but see Little Egret regarding possible existence of a dark
morph...). White morph most likely to be confused with Little Egret. In breeding
plumage shows two or three long, wiry hindcrown plumes just like latter....West
African nominate race [gularis] very close to Little in structure (but with longer
tibia
and slightly shorter tarsi)....Nominate race best separated from Little by slightly
heavier, dark brown to pale brownish bill (thicker-billed look being enhanced by
deeper ‘jowl’ of feathering underneath bill base) and distinctly longer tibia, but
beware darkening effect of water on bill. Outside breeding period, lores usually
pale greenish or yellowish, whereas in Little they are usually greyish or gray-blue.
At the height of breeding period they may be orange in both species.” –p. 93.

Cramp & Simmons. BWP Vol. 1
“White morph of Reef heron E. gularis much more difficult [than Cattle Egret and
Squacco Heron] to distinguish, being of same size, with similar plumes (though
shorter on head), all-white plumage, and dark legs with yellow feet; but has
thicker bill (grey-brown in West African race gularis and yellow in Red Sea race
schistacea), less graceful character, and duller, dark olive-green legs. Rare
melanistic Little Egrets have grey to dark slate plumage, with or without dark chin
and throat, and are even more difficult to distinguish from normal dark E. gularis,
except by thinner, black (not yellow or grey-brown) bill and paler, purer yellow
feet.” –p. 290

Importantly, this work provides the only real quantitative data. Note that the bill
of
gularis is only fractionally longer than that of garzetta in absolute terms, but that
the relative difference might be important (i.e., gularis appears to be slightly
smaller, at least in terms of wing length). The much shorter tarsometatarsus of
gularis (and presumably also its longer tibiotarsus, measurements of which are not
provided, but see Beaman and Madge above) seems very promising as field-usable
character.

The tabs will inevitably be garbled in the data below, but the measurements are
means in mm, followed, where possible, by standard deviation, sample size, and
range.

gularis garzetta
bill 83.8 (3.30, 21) 79-89 82.0 (n = 34) 67-93
tarsometatarsus 89.8 (4.45, 19) 82-94 99.2 (n = 34) 78-112
wing (flat) 265 (11.9, 23) 244-285 276 (n = 34) 245-303


Hancock, J. & J. Kushlan. 1984. The Herons Handbook. Harper & Row.
This source contains much useful information, but not a great deal of identification
analysis. Some statements differ somewhat from those in the sources cited above
(e.g., regarding the length of head plumes).

“The race gularis is dimorphic, but most individuals are dark-plumaged with a
white chin and variable yellow to dark brown legs. The bill and legs turn black
when breeding. The head plumes are somewhat shorter than in garzettta. White
phase gularis often have some dark feathers in the plumage. The bill of this race is
relatively thick and long.” –p. 128.

What is my opinion on the whole subject? Well, I'm not that well read on it all (I'm most familiar with New World taxonomy) but I think Shai makes a really great point when he says:

Thus, the question that ought to be haunting North American listers is not “Is my
Western Reef-Heron really a Little Egret?”—but rather, “Can I be sure that my North American Little Egret was not actually a white morph gularis Western Reef-Heron?”

Maybe when I actually get out and see this bird, I'll read more deeply and post my own opinion. For now, I'll enjoy the pictures and debate remotely.

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