[Rob Williams]

I've just come back from a few days in East Anglia where I was able to see both Little and Great White Egrets. I notice, having also visited Oz this year, that they do not have the same scientific names up here and down there.

Little Egret is Egretta Garzetta in both hemispheres, but the Great (White) Egret is Egretta Alba here and Ardea Alba down under; does this mean they are separate species?


Rob

[Keith Dickinson]

Just checking on Avibase and the Oz, Gt white egret is the Eastern White Egret, Ardea modesta, rather than the Western white egret, Ardea alba. According to Avibase alba is absent from Australia. However if you input Egretta alba into Avibase it does bring up Ardea alba so obviously the latin names have been changed at some point. Interesingly on Bubo listing the latin for Gt white egret is Casmoderus albus, which when entered into Avibase brings up Ardea alba.

Just got the page up from Opus, it explains a bit about the species. Looks like there are a few sub-species that Avibase may be considering as full species.
http://www.birdforum.net/opus/Ardea_alba

[Richard Klim]

Originally Posted by Keith Dickinson

Just checking on Avibase and the Oz, Gt white egret is the Eastern White Egret, Ardea modesta, rather than the Western white egret, Ardea alba.

Eastern Great Egret modestus/modesta was split by Kushlan & Hancock 2005 (The herons), although they admitted that the split deserves critical examination. IOC is so far the only worldwide 'authority' recognising it.

Originally Posted by Keith Dickinson

... if you input Egretta alba into Avibase it does bring up Ardea alba so obviously the latin names have been changed at some point.

The generic assignment of Great Egret was discussed in an earlier thread, in which it was noted that AERC (Association of European Records and Rarities Committees) TAC's (Taxonomic Advisory Committee's) Taxonomic Recommendations (Dec 2003) provide a useful overview:

"Although Voous (1973) preferred to call this species Ardea alba, he maintained Egretta alba in his List of Recent Holarctic Bird Species. The inclusion of this species in Ardea is supported by DNA-DNA hybridisation data (Payne & Risley 1976, Sheldon 1987b, Sheldon et al. 1995 and Sibley & Monroe 1990); Great White Egret is more closely related to Ardea than to Egretta. It was listed as Ardea alba by Mayr and Cottrell (1979, Peters’ Check-list of Birds of the World, Vol. 1, 2nd ed., pp 203-204). The relationships among the races are not clear. A. a. modesta may be a separate species, but extensive comparisons among all forms have not been done. Accepted as Ardea alba by AOU 1995 and in BOURC (1996). The CSNA and A.J. Helbig, however, preferred to place Great White Egret in the genus Casmerodius (Sangster et al. 1997; A.J. Helbig in litt.). Phylogenetic analyses based on DNA-DNA hybridisation indicate that Great White Egret is not closely related to the Egretta clade and instead suggest a closer relationship with Bubulcus and Ardea. However, given the unresolved relationships between Ardea, Great White Egret, Intermediate Egret Mesophoyx intermedia and Cattle Egret Bubulcus ibis, the CSNA believes that the inclusion of Great White Egret in Ardea (e.g. AOU 1995, BOURC 1997) is premature. Until the relationships of Great White Egret are better understood, the CSNA prefers to place it in a monotypic genus Casmerodius (cf. Inskipp et al. 1996) (Sangster et al. 1997). A.J. Helbig (in litt.) commented on his personal point of view: ‘Molecular studies confirm two monophyletic families (Sheldon et al. 2000). Great White Egret is equidistant from Ardea and Bubulcus, thus retained in a separate genus (Casmerodius). Relationships of Intermediate Egret (Mesophoyx / Egretta) are unknown.’ It should be noted, however, that in the field, intermedia shows intermediate features between Bubulcus and Casmerodius, suggesting a position in between these two taxa rather than in Egretta. If Great White Egret were to be placed in Ardea, the relationships of Bubulcus and Mesophoyx would need to be re-examined as well. In the field, Intermediate Egret shows more similarities to Cattle Egret and Great White Egret than to any of the Egretta species (G. De Smet, pers. observations). Although it is clear that the status quo (retaining intermedia and alba in Egretta) is wrong, this case clearly shows the need of Guidelines for assigning generic status and consultation among TCs before adopting generic changes. The rule of ‘monophyly’ seems to be applied in various ways by different committees. In addition, more research on the genetic relationships of intermedia is crucial, before a satisfactory decision can be reached. With two rejections for each option (Casmerodius albus or Ardea alba) only an arbitrary decision is possible. There is agreement that Great White Egret must leave Egretta but no consensus that it must enter Ardea or Casmerodius. Given the uncertainty about the relationships of Intermediate Egret and the possible implications for Cattle Egret, a cautious approach is needed. Therefore, Great White Egret is provisionally placed in Casmerodius albus until its relationships are resolved."

In summary, some current positions include:

• Ardea: Dickinson (Howard & Moore), Clements, IOC, AOU, ABA, BOURC, OSME
  
• Casmerodius: BirdLife, AERC, Dutch Birding, OBC
  
• Egretta: HBW, BWP, African Bird Club

Richard

[Rob Williams]

Thanks for those answers, I shall just take it that they are the same species.

[James Lowther]

so basically rob,
Egretta alba and Ardea alba are different names for the same species, the people who call it the former reckon the bird is more closely related to e.g little egret, the people who call it the latter reckon it's closer to e.g. grey heron.

however, on top of that some people (but seemingly in the minority at the moment) think that the great egrets in eastern asia and australasia are a different species from the european ones, and call the former Eastern great egret with the scientific name Egretta (or Ardea) modesta.

confusingly that means different people could potentially call the same australian great egret either Ardea alba, or Egretta modesta

confusing hey??

James

[sideshow bob]

Originally Posted by James Lowther

so basically rob,
Egretta alba and Ardea alba are different names for the same species, the people who call it the former reckon the bird is more closely related to e.g little egret, the people who call it the latter reckon it's closer to e.g. grey heron.

however, on top of that some people (but seemingly in the minority at the moment) think that the great egrets in eastern asia and australasia are a different species from the european ones, and call the former Eastern great egret with the scientific name Egretta (or Ardea) modesta.

confusingly that means different people could potentially call the same australian great egret either Ardea alba, or Egretta modesta

confusing hey??

James

Excellent summation James, a perfect example of why I find these taxonomy threads so fascinating and frustrating! But mainly fascinating.....

[Richard Klim]

Originally Posted by James Lowther

confusingly that means different people could potentially call the same australian great egret either Ardea alba, or Egretta modesta

confusing hey??

...or Casmerodius (albus) modestus.

Richard

[John_WA]

To add to this, in their new Australian checklist, Christidis & Boles (2008) have now split the great egrets here (Australia) from alba and have re-classified them as Eastern Great Egret Ardea modesta

John

[colonelboris]

Originally Posted by John_WA

To add to this, in their new Australian checklist, Christidis & Boles (2008) have now split the great egrets here (Australia) from alba and have re-classified them as Eastern Great Egret Ardea modesta

John

Anyone other than the Australians and the IOC go for this treatment? Not that I'm trying to get an extra tick...

[njlarsen]

Does not seem that neither Clements or Howard & Moore have gone for this one yet. Clements should have another update this fall sometime, H&M next year?

Niels

[Richard Klim]

Originally Posted by colonelboris

Anyone other than the Australians and the IOC go for this treatment? Not that I'm trying to get an extra tick...

Hi Tony, I'm sure you're enjoying a tickfest in Oz!

Unsurprisingly, Dutch Birding also recognises Casmerodius modestus (with effect from 1 Jan 2009), following Christides & Boles 2008.

Ref. Redactie Dutch Birding 2009. Redactiemededelingen: Naamgeving van taxa in Dutch Birding. Dutch Birding 31(1): 35-37.

Richard

[colonelboris]

Originally Posted by Richard Klim

Hi Tony, I'm sure you're enjoying a tickfest in Oz!

[bad taste]More ticks than a hedgehog! [/bad taste]
I'll be moving out to the suburbs in a few weeks, so hopefully get to see a few more species. Be nice to get near 300 by the end of the year, but with the travels time to and from work, there won't be much light left in the evenings, even in summer. On the plus sides, we're next to some national parks, so the weekends should be good (wife and kids permitting).

Originally Posted by Richard Klim

Unsurprisingly, Dutch Birding also recognises Casmerodius modestus (with effect from 1 Jan 2009), following Christides & Boles 2008.

Ref. Redactie Dutch Birding 2009. Redactiemededelingen: Naamgeving van taxa in Dutch Birding. Dutch Birding 31(1): 35-37.

Richard

It's always so tempting to take the Dutch line - it would certainly add a few species (imaine being able to tick Wittekwikstaart and Rouwkwikstaart...) - but it feels slightly wrong to do so. Funny, really, as most of their ideas are eventually adopted elsewhere. The other argument is 'when in Rome', so if Christides and Boles say it is...
I'll see how it pans out.
Cheers!

Tony

[colonelboris]

One thing that always amused me:

Western Great Egret, Casmerodius albus (IOC)
Great White Egret, Ardea alba (BOU)
Silberreiher, Egretta alba (Schweizerische Vogelwarte)

And they're all the same bird...

[Richard Klim]

Originally Posted by colonelboris

One thing that always amused me:

Western Great Egret, Casmerodius albus (IOC)
Great White Egret, Ardea alba (BOU)
Silberreiher, Egretta alba (Schweizerische Vogelwarte)

And they're all the same bird...

It's all about offering the consumer choice...

Richard

[birdboybowley]

So where's the geographical boundary for Eastern/Western occur?

[njlarsen]

Originally Posted by birdboybowley

So where's the geographical boundary for Eastern/Western occur?

The Clements checklist gives alba to central Asia, modesta from south and east Asia to Australia. Not a lot of detail in there!

Niels

[Daniel Philippe]

Originally Posted by birdboybowley

So where's the geographical boundary for Eastern/Western occur?

In Kushlan and Hancock 2005 for Eastern Great Egret :

Breeding range : It nests in Pakistan, India, Sri Lanka, Bangladesh, Myanmar, Thailand, China (Heilongjiang, Shandong, south Yunnan and Fujian (historically), Guangxi (Zhou 2003), Korea, north-east Russia (south Ussuriland), Japan (Kanai 1990, Narusue 1992, Ueda 1994), Indochina, Indonesia (Sumatra, Java, Borneo, Sulawesi, Lesser Sundas, Moluccas, Irian Jaya), Papua New Guinea, Solomon Islands, Australia (except drier interior), and New Zealand (a single colony on South Island (Moore 2001). There is not now breeding known in Malaysia or Philippines (Lansdown et al. 2000).

Non-breeding range : It is a summer visitor to Japan as far as Hokkaido and the Kurils (Iijima 1984, Kosugi 1993, Shimada et al. 1994). It occurs in the non-breeding season from extreme south Japan (Honsu, Ryukus Islands), southeast China, Hainan, and Taiwan, through the East Indies, Australia, and New Zealand.

[birdboybowley]

Thanks Niels and Dan

[Richard Klim]

Rasmussen & Anderton 2005 indicates that the linear dimensions of albus are on average c25% greater than those of modestus. So assuming that both forms are structurally similar, that would suggest that the mass/volume of albus is typically c95%(!) greater than that of modestus.

Are empirical weight data for the two forms given by Kushlan & Hancock (or any other source)?

Richard

[colonelboris]

Originally Posted by Richard Klim

Rasmussen & Anderton 2005 indicates that the linear dimensions of albus are on average c25% greater than those of modestus. So assuming that both forms are structurally similar, that would suggest that the mass/volume of albus is typically c95%(!) greater than that of modestus.

Are empirical weight data for the two forms given by Kushlan & Hancock (or any other source)?

Richard

I'm confused - I read that A. a. modesta was the largest ssp. and was noticeably larger than A. a. alba.

[Daniel Philippe]

Originally Posted by Richard Klim

Are empirical weight data for the two forms given by Kushlan & Hancock (or any other source)?

Kushlan and Handcock 2005:

Great Egret - weight: 930-1700 g; length: 85-102 cm
Eastern Great Egret - weight: males 970 g, females 760 g; length: 83-103 cm.

[Richard Klim]

Originally Posted by colonelboris

I'm confused - I read that A. a. modesta was the largest ssp. and was noticeably larger than A. a. alba.

Tony, your user title (I'm upside down) explains it - remember to turn your books the other way up now that you're in Oz.

Richard

[Richard Klim]

Originally Posted by Daniel Philippe

Kushlan and Handcock 2005:

Great Egret - weight: 930-1700 g; length: 85-102 cm
Eastern Great Egret - weight: males 970 g, females 760 g; length: 83-103 cm.

Thanks Daniel. Those virtually identical lengths look rather surprising though.

R&A 2005 (obviously using a different measuring technique) gives lengths as:

• albus - m975-995, f945-965
• modestus - m760-775, f720-730

which suggests that albus is typically c30% longer than modestus. [My earlier figure of 25% referred to the difference between the sums of the averages of all given linear dimensions: length + head + tail + bare leg.]

The only comparative dimensions given by BWP are for average male wing length: 438 (albus), 363.5 (modestus) - ie albus c20% longer.

Richard

[colonelboris]

Originally Posted by Richard Klim

Tony, your user title (I'm upside down) explains it - remember to turn your books the other way up now that you're in Oz.

Richard

Ah, that explains it...
Going fairly well out here - got some pictures of the bird in question, too...
http://www.tonykeenebirds.co.uk/abirds/greategret.html
Shame about the rubbishness of the Kodak P850, though, as the bird was about four metres away from me.

[Richard Klim]

Originally Posted by colonelboris

Going fairly well out here - got some pictures of the bird in question, too...

Nice pics Tony, but a pity you didn't position a metre rule alongside the bird so that we could establish its dimensions.

Richard