[tomjenner]

On January 5th I saw and photographed some grebes on Lake Atitlan in Guatemala and I am interested in birders' comments about their identity. I have posted several photos on my website (http://www.mayanbirding.com) which show the main features, though they are very poor quality. Supposedly, the Atitlan Grebe is now extinct in its pure form, but there may still be hybrids with Pied-billed Grebe, which is a more recent arrival at the lake. I do not see many Pied-billed Grebes this far south, so I need some help from people with more experience.
What struck me most is that the birds were in full summer (alternate) plumage on January 5th, with a black bib and black band down the bill. This seems far too early for normal Pied-bills. The Atitlan Grebe had these features throughout the entire year. The Atitlan Grebe was also larger and had a darker head and neck and was flightless. The website also has a black and white photo of an Atitlan Grebe for comparison.
It is possible that the resident Pied-billed Grebes have a different moult than those further north.
Any comments would be very welcome as the status of the Atitlan Grebe has been uncertain for many years.
Tom

[Jane Turner]

Hi - I can't claim to know a think about S.American grebes however this bird looks huge by comparison to the Stifftail duck its behind!

http://tomjenner.com/mayanbirding/gallery/water_birds/misc_water_birds/Grebe%20Atitlan%20Jan%2004%20(22).JPG

[tomjenner]

Hi Jane
It was definately bigger than the Ruddy Ducks that were beside it, but slightly smaller than the American Coots it was with. my problem is that I'm just not familar with the relative sizes of these species in the field and I don't think that the lengths in the field guides are necessarily going to give an acurate impression of how they look in the field. I'm hoping that some North American birders who have a lot more experience with these species will be able to make some comments.
Tom

[Rasmus Boegh]

First, I've seen loads of Pied-billed Grebes, but obviously no Atitlan (so my judgement is somewhat second hand).

First, a few comment on size:
On the photos with the grebe together with four American Coot's and a single Common Moorhen respectively, the size seems to fit perfectly with a Pied-billed (and not the larger Atitlan). The one with shown with a single Ruddy Duck does seem quite large, but it can obviously be very hard to judge.

Colour:
There's a single great colour-photo of the Atitlan Grebe in "Handbook of Birds of the World" vol. I, and it clearly shows a bird that is somewhat greyer than most Pied-billed (but in the same book they later write; "Browner with less grey than P. podiceps"!!!). Especially on lower neck. Obviously I dont know if the individual on that photo is the norm, but it's the only colour photo I've seen of the species. All the birds featured on your photos seem to be rather brownish on the lower neck, hence rather Pied-billed like... The Atitlan Grebe on the colour-photo also appears a bit darker in general than the Pied-billed I've seen. Yet again, the birds on your photos seem to light for an Atitlan.

Bill:
I've heard (and read) about many claiming that the bill is (was) more white in Atitlan than Pied-billed Grebe. Well, I've seen several Pied-billed with a bill that was as white as white gets! Also, the bill is supposely more massive in Atitlan, especially near base (and this also fits the two photos I've seen, the colour and your b/w). It's hard to judge the size of the bill from your new photos...

I would be very pleased if any "clean" Atitlan Grebes were found, but I'm quite sure the only way that could be done, is to get a few samples (blood or feathers) containing DNA, and then check them against samples of known Atitlan Grebe's on various museums. Perhaps this would also help on the whole "is it a species or is it not" issue.

Ohh yes, I almost forgot... great page. I just have to visit Guatemala at some point... Need that Horned Guan!

[Rasmus Boegh]

I found a page with another (admittedly rather poor) b/w picture of an Atitlan Grebe. Perhaps more interestingly, it also describes some of the ways to recognize it and even some of the things known on behavior, incl. voice.

http://www.sths.org/students/project2000/pastort.htm

[cuckooroller]

Tom,
Here's a little better copy of the photo Rasmus linked.

[tomjenner]

Thanks Steve
This shot definately shows a bird with a darker head and neck than the ones in my photos. I think its pretty clear that they are definatley not pure Atitlan Grebes, but I would still like to know for certain if they are pure Pied-bills. My main concern is still the black bib and bill band in early January of at least two individuals; ie not a single abberant bird.
Does anyone know anything about the moult of Pied-billed Grebes in the southern part of their range?
Tom

[Rasmus Boegh]

The last B/W photo is rather dark... Judging from the great colour-photo in HBW, the B/W photo on your site and various drawings I have seen it is also TOO dark. Still, the Atitlan Grebe should be overall darker than Pied-billed.

I'll see if I can remember to ask Jon Fjeldså next time I see him. Don't know if he's got any specific knowledge on the Atitlan, but he is surely one of the (if not THE) persons who knows the most about Neotropical Grebes otherwise.

[tomjenner]

Thanks Rasmus, that would be great. Unfortunately, I don't have a copy of the Handbook of the Birds of the World, so I can't check the photo and I doubt if I will find a copy anywhere in El Salvador.
Tom