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Old Friday 11th August 2017, 02:07   #1
bugmat
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Gray or Cocoi Heron ID - Trinidad

Hi All

Saw this heron late this evening (sun was setting hence the softness of the shots). Also note this was after heavy rains most of the day so the bird is wet (we are experiencing rainy season now - it brings a lot of migrants).

- it was smaller than a Great Egret (single shot doesn't show this well but it was near one for a while)
- general impression is a gray heron - neck, chest, thighs etc
- no rufous at all
- dark cap doesn't go below or around lower part of eye
- has black crest plumes which are pretty short
- faint eye streak above
- in flight greater wing & primary coverts look mostly gray
- has the marquee headlights on the carpal/wing bend
- yellow legs
- has streaks of white on the crown

I was thinking an almost-adult gray heron, but realise juvenile cocoi herons are grayish also... cannot find enough images of either juveniles online to make a confirmation.
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Old Friday 11th August 2017, 08:59   #2
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Smaller than Great Egret doesn't suggest Grey to me; it is larger, though there is some overlap. There's also something about this bird that just 'doesn't look right' for 1st- or 2nd-year Grey (which I see a lot of). Never seen Cocoi, so can't say on that, unfortunately.

PS correct spelling Grey Heron
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Old Friday 11th August 2017, 11:26   #3
bugmat
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Quote:
Originally Posted by Nutcracker View Post
Smaller than Great Egret doesn't suggest Grey to me; it is larger, though there is some overlap. There's also something about this bird that just 'doesn't look right' for 1st- or 2nd-year Grey (which I see a lot of). Never seen Cocoi, so can't say on that, unfortunately.

PS correct spelling Grey Heron
It's spelt both ways depending on region

And yes grey heron adults are smaller than cocoi and great blue adults and slightly smaller than great egret adults - that's a general fact.

I read in one place (website not a reference site) that Cocoi juveniles are the same size as the adults but couldn't verify and that is really the sticking point - not much info on juveniles that I could google
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Old Friday 11th August 2017, 12:50   #4
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Generally for birds, at least the wings are fully grown before the bird is able to fly off to somewhere new. The body generally too, while things like the bill (e.g., on a shorebird) can still grow a little.

Compare: http://www.birdforum.net/opus/Cocoi_Heron

Notice that at least some of the images show the cap going down to the gape line behind the eye, something your photo does not show.

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Old Friday 11th August 2017, 16:38   #5
bugmat
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Originally Posted by njlarsen View Post
Generally for birds, at least the wings are fully grown before the bird is able to fly off to somewhere new. The body generally too, while things like the bill (e.g., on a shorebird) can still grow a little.

Compare: http://www.birdforum.net/opus/Cocoi_Heron

Notice that at least some of the images show the cap going down to the gape line behind the eye, something your photo does not show.

Niels
Ok well that coincides with what I read - juvenile cocois are generally the same size as adults - I've confirmed with some local experts too - this is an adult gray/grey heron. Thanks to you both.
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Old Friday 11th August 2017, 16:56   #6
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Originally Posted by bugmat View Post
Ok well that coincides with what I read - juvenile cocois are generally the same size as adults - I've confirmed with some local experts too - this is an adult gray/grey heron. Thanks to you both.
I'm not sure your conclusion is right.

This is not a juvenile nor an adult. It is an immature. Adult size indeed.

I don't why it is not a Cocoi Heron.
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Old Friday 11th August 2017, 17:07   #7
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My excuse s that I have no books here to check the features but...why is Great Blue Excluded from the equation?


A
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Old Friday 11th August 2017, 17:12   #8
Nutcracker
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I''ve been looking again, and struggling to find any distinguishing features between 1st-summers of Cocoi and Grey Herons.

I'd favour Cocoi though, simply on it being the most local species.

Looked up sizes:
Grey: 1-2.1 kg
Great Blue: 1.8-3.6 kg
Cocoi: 1.1-3.2 kg
Great Egret: 0.7-1.5 kg
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Old Friday 11th August 2017, 17:13   #9
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My excuse s that I have no books here to check the features but...why is Great Blue Excluded from the equation?


A
White thighs (orange on Great Blue)
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Old Friday 11th August 2017, 17:18   #10
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This is a close up of a juvenile Cocoi, seems to fit pretty well: http://www.wikiaves.com.br/152025&t=s&s=10162

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Old Friday 11th August 2017, 17:49   #11
Nutcracker
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Originally Posted by njlarsen View Post
This is a close up of a juvenile Cocoi, seems to fit pretty well: http://www.wikiaves.com.br/152025&t=s&s=10162

Niels
Another immature Cocoi looking similar, including grey & white-streaked forehead: https://commons.wikimedia.org/wiki/File:Garza_Cuca.JPG
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Old Friday 11th August 2017, 18:03   #12
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Originally Posted by Nutcracker View Post
White thighs (orange on Great Blue)
But not if it's sub-ad?


A
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Old Friday 11th August 2017, 18:17   #13
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Originally Posted by andyadcock View Post
But not if it's sub-ad?


A
On first years, Great Blue thighs are orangey-brown toned; not as bright as adults, but still obvious enough:
https://commons.wikimedia.org/wiki/F...ron_at_SHL.jpg
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Old Friday 11th August 2017, 18:22   #14
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But not if it's sub-ad?


A
Actually I didn't reply earlier because I was not 100% to exclude Great Blue Heron.

It is not a Grey Heron for sure, OP claims it was small (better for Cocoi) although I see a very thick beak (better for Great Blue)...

Now, with Nutcracker's explanation, I agree we can exclude Great Blue too, so Cocoi Heron immature it is!
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Old Friday 11th August 2017, 18:23   #15
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Quote:
Originally Posted by andyadcock View Post
But not if it's sub-ad?


A
In HBW under GBH is stated:
Quote:
Juveniles of present species and A. cinerea can be distinctly more problematic to separate, although many of the same features that apply to adults can be useful, with rufous thighs and tips to wing-coverts being two of the most important characters that identify A. herodias at this age
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Old Friday 11th August 2017, 18:50   #16
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In HBW under GBH is stated:

Niels
Thanks

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Old Friday 11th August 2017, 23:58   #17
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My error in using juvenile - bad habit. it is an immature/sub-adult bird I can agree with that yes, but it is probably close to adulthood.


I discounted cocoi for several reasons but the most pertinent is that from all accounts (from a local member of the rare bird committee here and other veterans) is that even juvenile/immature cocoi herons are larger than this bird was.

There is also the fact that the cap is limited - cocoi even in those immature birds posted have a fuller cap closer to the area above and below (ie surrounding) the eye. Also note the caps in those two birds are gray/duller in parts (as described in the link below). In my bird there is a faint area above the eye and the cap is full and not patchy bar the white-streaking. THe lore sin those two birds are also distinctly more yellow in patches than this bird which is blander there (not sure if that is jsut my perception or colour balance in any of the photos but in real life it wasn't bright yellow like those two photos of immature cocoi). Also note one of my photos shows short plumes - immature cocoi are supposed to lack these:

http://www.heronconservation.org/styled-5/styled-19/

^ The above link also notes southern Cocoi are larger than northern birds.

And last the classic "headlight" on GH is supposed to be much more prominent than in any cocoi - I think that can be seen in my bird, which has a more prominent white aptch at the carpal bend than those two immature/juvenile cocoi posted.

Cocoi are the largest herons in South America and the Great Blue is not far off in size, with the Great Egret & Gray Herons significantly smaller by at least a foot. Also I have seen a fair few cocoi heron up close.

This is in no way a GBH just for the earlier poster. GBH have rufous at all stages - this is an immature one I shot of a GBH (attached)

Funnily enough a veteran birder and I saw another sub-adult Gray heron today - looked just like this bird but was dry instead of soaked (also attached). I suspect it is the same bird as has been noted they are rare, but not accidental here.

Thanks again.
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Old Saturday 12th August 2017, 00:14   #18
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Your bird is definitely not a Grey Heron. And as I explained above, don´t rely on size. What you have seen is not enough to exclude Great Blue on size alone, size impression in the field as well as on photos can be totally wrong.

Look here a Great Egret Looking larger than a Great Blue Heron.

http://www.natureintheframe.com/img/...20026712-4.jpg

Great Blue is excluded on colour, so your bird is a Cocoi.
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Old Saturday 12th August 2017, 03:45   #19
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Your bird is definitely not a Grey Heron. And as I explained above, don´t rely on size. What you have seen is not enough to exclude Great Blue on size alone, size impression in the field as well as on photos can be totally wrong.

Look here a Great Egret Looking larger than a Great Blue Heron.

http://www.natureintheframe.com/img/...20026712-4.jpg

Great Blue is excluded on colour, so your bird is a Cocoi.
I'll not argue too much (though that is what forums are for) - the ornithologists here in trinidad will decide (I've submitted the bird as a report to be decided by a panel) and I'll update the thread when I get a response.

I cannot see how you can definitively tell me it isn't a gray heron when the facts match, and it is a bird that has been recorded here annually (though in very small numbers)... your opinion regarding size goes against records here and elsewhere including the site I linked and the field guides of both here adn Venezuela... and size was but one factor I used in judgment rahter than the only one.

I can understand someone saying it could either be gray or cocoi, and then going for cocoi simply due to likelihood (though that is also a bit of a fallacy as we'd never have rare birds if everything was common)

...but to say it's definitely not a gray based on nothing more than that likelihood when it could fit for either bird - and both have been recorded here in multiple years in recent times -well in my opinion that cannot logically be a definitive conclusion.

Your photo showing a great egret lookin taller than a great blue heron is not a counterargument to my point about cocois being generally larger than gray herons, or gray herons being similar in size to great egrets, for several reasons (1) the egret's neck is extended while the GBH is not which of course means it will stand taller and (2)parallax error - the closer bird looks bigger than it is in relatio to the further because of the angle of view of the photographer (3) variation in individuals which also depends on age and maturity

I saw both species (this heron and two different great egrets) stand beside each other in the same area for several minutes - i think I can judge if a bird is roughly the same height or significantly large/smaller even within an acceptable range of variation.

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Old Saturday 12th August 2017, 05:16   #20
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I cannot see how you can definitively tell me it isn't a gray heron when the facts match, and it is a bird that has been recorded here annually (though in very small numbers)... your opinion regarding size goes against records here and elsewhere including the site I linked and the field guides of both here adn Venezuela... and size was but one factor I used in judgment rahter than the only one.

I can understand someone saying it could either be gray or cocoi, and then going for cocoi simply due to likelihood (though that is also a bit of a fallacy as we'd never have rare birds if everything was common)

...but to say it's definitely not a gray based on nothing more than that likelihood when it could fit for either bird - and both have been recorded here in multiple years in recent times -well in my opinion that cannot logically be a definitive conclusion.
I agree that it's definitely not Grey/Gray. This conclusion isn't based on likelihood, but based on the appearance of the bird and familiarity with Grey Heron. (It's interesting that most comments saying it's not Grey are from European birders, who are also probably familiar with Grey).

For me, the main factor against Grey is the head pattern. I don't think Grey would ever show such an extensively black crown reaching as far as the bill, or show the streaked forecrown present on this bird. Adult Grey has a fully white crown with the black streak terminating above the eye, not reaching the bill. Juvenile Grey shows an extensively grey crown, much paler than on your bird. Older immatures would be intermediate, but still not show black extending as far as the bill. The black also seems to extend low onto the sides of the head behind the eye, compared to a typical Grey Heron.

Supplemental features that look odd for Grey are an apparently heavy bill and what look to me like very dark (blackish) legs on the flight photos (I can't see the legs as being yellow, as you suggested in the original post).

I am not at all familiar with Cocoi, so can't really comment much on that ID, but from online photos that looks better to me than Grey.
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Old Saturday 12th August 2017, 07:53   #21
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I agree that it's definitely not Grey/Gray. This conclusion isn't based on likelihood, but based on the appearance of the bird and familiarity with Grey Heron. (It's interesting that most comments saying it's not Grey are from European birders, who are also probably familiar with Grey).

For me, the main factor against Grey is the head pattern. I don't think Grey would ever show such an extensively black crown reaching as far as the bill, or show the streaked forecrown present on this bird. Adult Grey has a fully white crown with the black streak terminating above the eye, not reaching the bill. Juvenile Grey shows an extensively grey crown, much paler than on your bird. Older immatures would be intermediate, but still not show black extending as far as the bill. The black also seems to extend low onto the sides of the head behind the eye, compared to a typical Grey Heron.

Supplemental features that look odd for Grey are an apparently heavy bill and what look to me like very dark (blackish) legs on the flight photos (I can't see the legs as being yellow, as you suggested in the original post).

I am not at all familiar with Cocoi, so can't really comment much on that ID, but from online photos that looks better to me than Grey.
Yes, European birders see Grey Herons daily or very often, and there is never one like this. Head pattern is the most obvious, as the shape of head/bill, and other details in the plumage.

On my side, I spent most of last year in Colombia and have seen many Cocoi Herons. The op bird has nothing against being one. We have excluded Great Blue so the case is settled.
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Old Saturday 12th August 2017, 09:47   #22
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I agree that it's definitely not Grey/Gray. This conclusion isn't based on likelihood, but based on the appearance of the bird and familiarity with Grey Heron. (It's interesting that most comments saying it's not Grey are from European birders, who are also probably familiar with Grey).

For me, the main factor against Grey is the head pattern. I don't think Grey would ever show such an extensively black crown reaching as far as the bill, or show the streaked forecrown present on this bird. Adult Grey has a fully white crown with the black streak terminating above the eye, not reaching the bill. Juvenile Grey shows an extensively grey crown, much paler than on your bird. Older immatures would be intermediate, but still not show black extending as far as the bill. The black also seems to extend low onto the sides of the head behind the eye, compared to a typical Grey Heron.

Supplemental features that look odd for Grey are an apparently heavy bill and what look to me like very dark (blackish) legs on the flight photos (I can't see the legs as being yellow, as you suggested in the original post).

I am not at all familiar with Cocoi, so can't really comment much on that ID, but from online photos that looks better to me than Grey.
Was thinking overnight what more I could add, but John's expressed it all much better than I could

Of saying it isn't Cocoi because it is small, worth remembering that all herons have quite a wide range of size variation; on published length measurements, a big Grey (90-98 cm) can be taller than a small Cocoi (95-127 cm).
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Old Saturday 12th August 2017, 10:29   #23
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Funnily enough a veteran birder and I saw another sub-adult Gray heron today - looked just like this bird but was dry instead of soaked (also attached). I suspect it is the same bird as has been noted they are rare, but not accidental here.
Once again, this doesn't look like a Grey Heron. Too dark, 'dirty' grey, legs too black, and too much black on the crown.
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Old Saturday 12th August 2017, 11:47   #24
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Thanks again for the comments. I'll bump the thread when the committee responds to the report.
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Old Saturday 12th August 2017, 14:22   #25
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If I saw this in the field I would not suspect it to be other than Cocoi, to be honest.

Perhaps this is worth posting to the FB group Advanced Bird ID.
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