Potoo: Nyctibius aethereus vs griseus (1 Viewer)

[rosmo01]

This is possibly a common potoo, yet it has the two characteristics that are supposedly distinctly long-tailed, namely the white malar and the absence of black breast streaks. If these two characteristics are not definite what are? The local bird specialist was adamant it was long-tailed.
Location: Amboró National Park, Bolivia.

 

[Deb Burhinus]

Wow, quite impressed you even saw it in the first place - amazing! (Sorry can’t help with the ID)

 

[THE_FERN]

We need Josh's expertise I think. My view: probably can't be certain from this photo. The key characters of long tail and heavy barring on that tail aren't visible. Although the breast spots are mentioned in some guides (e.g. birds of Peru), ebird photos of common suggest this is variable: there's at least one photo of a plain breasted specimen.

I suspect your guide knew what he was talking about. He should have known tail length was the key criterion. (If it's important to you, you could email him and ask "please help: how do I identify...". You can judge whether he knew what to look for by the reply.)

Yes these birds are super cryptic. But you can find them... I found one right outside Asuncion cathedral...

 

[rosmo01]

We need Josh's expertise I think. My view: probably can't be certain from this photo. The key characters of long tail and heavy barring on that tail aren't visible. Although the breast spots are mentioned in some guides (e.g. birds of Peru), ebird photos of common suggest this is variable: there's at least one photo of a plain breasted specimen.

I suspect your guide knew what he was talking about. He should have known tail length was the key criterion. (If it's important to you, you could email him and ask "please help: how do I identify...". You can judge whether he knew what to look for by the reply.)

Yes these birds are super cryptic. But you can find them... I found one right outside Asuncion cathedral...

I shot this in 2012, so a long time ago, and contact details unavailable now. But I've uploaded an image where the tail is visible to show the distance between wing tip and tail tip. The question is what's considered tail extending well beyond closed wing tips?

It's a bit frustrating with different key characters - e.g Birds of Ecuador state the white malar and the absence of black breast streaks. Birds of Bolivia only mention tail extending well beyond closed wing tips. Some the color (brown vs grey(er).

I also wonder if there are variations between the northern and southern populations. The one certain key is of course size, as the long-tailed is much larger.

Your find by the cathedral was amazing - I suspect 99,99% of humans will never notice it there.

Hopefully Josh will clarify..

 

[njlarsen]

I feel on the second image I can see where the wings end. Comparing with the images I see in Birds of the World (same images as in ebird I believe) this looks a lot more like Long-tailed than common.

Morten, go to Ebird.org, Explore, species and enter the species name. Click on the image in the banner at the top for larger versions.

Niels

 

[rosmo01]

I feel on the second image I can see where the wings end. Comparing with the images I see in Birds of the World (same images as in ebird I believe) this looks a lot more like Long-tailed than common.

Morten, go to Ebird.org, Explore, species and enter the species name. Click on the image in the banner at the top for larger versions.

Niels

Thanks for your input Niels! I've definitely checked eBird - together with many other sources, and I find it challenging to get a clear ID.

 

[THE_FERN]

Now we can see the 2 distinctive things: tail length and strong tail bars. Definitely long-tailed

 

[THE_FERN]

Just to say, you might consider giving the second one with the view of the tail to Opus. The photos there don't show this

 

[njlarsen]

Starting with you uploading one or both in the birdforum gallery would go a long way. And yes, we would love to have the second image in Opus.

Niels

 

[rosmo01]

I'm still struggling with consensus on this one. Are you on iNaturalist? It would be helpful if you contributed to the correct id on my observation there: https://www.inaturalist.org/observations/68288756

It would also help if an ornithologist or someone with experience with potoos could contribute.

When I summarize the available resources, all of them have one characteristic, but none agree on all:

white malar
the absence of black breast streaks
tail longer than wingtip (but not how much longer)
color (brownish vs grayish)

Plumage is notoriously variable and I would like to know the commons for the a. longicaudatus, which is the specimen here.

Birds of Bolivia is quite clear about the longer tail and pale wing coverts: https://birdsofbolivia.org/species-fact-sheets-2/potoos-guajojos/nyctibius-aethereus/ but I don't know if there are more details on the printed version. This is the only resource that pair these two characters. Here the coverts are dark and pale part seems to be on the back (perhaps scapulars), not the wing.

 

[THE_FERN]

I'm still struggling with consensus on this one. Are you on iNaturalist? It would be helpful if you contributed to the correct id on my observation there: https://www.inaturalist.org/observations/68288756

It would also help if an ornithologist or someone with experience with potoos could contribute.

When I summarize the available resources, all of them have one characteristic, but none agree on all:

white malar
the absence of black breast streaks
tail longer than wingtip (but not how much longer)
color (brownish vs grayish)

Plumage is notoriously variable and I would like to know the commons for the a. longicaudatus, which is the specimen here.

Birds of Bolivia is quite clear about the longer tail and pale wing coverts: https://birdsofbolivia.org/species-fact-sheets-2/potoos-guajojos/nyctibius-aethereus/ but I don't know if there are more details on the printed version. This is the only resource that pair these two characters. Here the coverts are dark and pale part seems to be on the back (perhaps scapulars), not the wing.

Hi

Unclear what you're after. No one here suggests this is common potoo. The main identification criteria are long tail and heavy barring on the tail [see Birds of Northern South America]. Your second photo demonstrates these.

I think you only have to look at the "headline" ebird photos for each species to see that only one of the criteria you list above is valid [=tail length]. I explained that the ebird photos demonstrate that the chest markings are variable. Those photos will show that malar is too; there is overlap with common and it's only useful if comparing with other species which lack this [Great, Andean etc]. Note that although Birds of Venezuela notes the malar on the plate, in the description it says "fairly distinct dusky malar" and doesn't highlight [italicise] it. In contrast, it does italicise: "tail cinnamon brown with up to 6 rather large but obscure or ill-defined dusky banks showing beyond wings". In comparison with common it says that species is "usually paler, lacks long and strongly graduated tail, and has more bands on tail." If you look on Opus here you'll see a pic of a grey-coloured long-tailed potoo...

The ebird photos show clearly what difference in tail length to expect. Your bird clearly meets that criterion. It has the dark thick tail bands and is long-tailed.

 

[rosmo01]

Hi

Unclear what you're after. No one here suggests this is common potoo. The main identification criteria are long tail and heavy barring on the tail [see Birds of Northern South America]. Your second photo demonstrates these.

I think you only have to look at the "headline" ebird photos for each species to see that only one of the criteria you list above is valid [=tail length]. I explained that the ebird photos demonstrate that the chest markings are variable. Those photos will show that malar is too; there is overlap with common and it's only useful if comparing with other species which lack this [Great, Andean etc]. Note that although Birds of Venezuela notes the malar on the plate, in the description it says "fairly distinct dusky malar" and doesn't highlight [italicise] it. In contrast, it does italicise: "tail cinnamon brown with up to 6 rather large but obscure or ill-defined dusky banks showing beyond wings". In comparison with common it says that species is "usually paler, lacks long and strongly graduated tail, and has more bands on tail." If you look on Opus here you'll see a pic of a grey-coloured long-tailed potoo...

The ebird photos show clearly what difference in tail length to expect. Your bird clearly meets that criterion. It has the dark thick tail bands and is long-tailed.

 

[rosmo01]

I'm after 2 or more specifics for positive ID, and very much appreciate your clarifications on "it does italicise: "tail cinnamon brown with up to 6 rather large but obscure or ill-defined dusky banks showing beyond wings"". This was new to me - which again proves how variable the field guides are. Birds 'of Ecuador is adament these two are distinct to the long tail:
"Long-tail never seems to show the patch of black breast streaks usually so obvious on common, and common never shows long-tailed's white malar."

It's important to be exact, also across platforms, which means it's important that same observation keeps same ID on each platform. Thus I would very much appreciate your corrective updates on iNaturalist. Otherwise it's my words against them, and the observation is in limbo with Birdforum and iNatualist being in conflict on same observation.

I should of course have done a better field work and confirmed it's size and nocturnal vocalization, but sometimes you mess up and forget how you arrived at the ID.

I will update image on Opus.

 

[THE_FERN]

[Edit]: I'm going to have to apologise. When I wrote these posts earlier I was using a mobile screen and said what I thought I could see in your photos. The ID points I mentioned above and general discussion is correct. However, using a larger monitor I can now see that the tail is not long enough for long-tailed potoo. This must be common potoo, therefore.

I'd also add to this and say that reviewing the dark bands on the tail on this screen makes them appear a lot lighter. I can also see from looking at the ebird photos again that this isn't a failsafe character either: in your photo we can see only a few broad dark[ish] bands and there are other common potoo photos with few dark tail bands. This means that tail length relative to wingtips remains the one single best character for distinguishing these 2 species.

[Ebird photos suggest that there are common potoos which apparently completely lack a paler maler]

I'm after 2 or more specifics for positive ID

Think I've given you those? Both involve the tail. Tail length is mentioned in all the field guides [the clue's in the bird's name...]. The dark spots are mentioned in at least 2 guides as I noted.

"Long-tail never seems to show the patch of black breast streaks usually so obvious on common, and common never shows long-tailed's white malar."

On the patch of breast streaks: do you see them on your photos? I don't... [I do see a few isolated spots]. However I don't believe this is a constant character in common potoo: please look at the ebird photos. The illustration in Birds of Peru for long-tailed shows a single "necklace" or line of breast spots.

I've discussed the malar—at best this is highly variable. If you look at photos you'll see this. [Do you feel your photos show a white malar? I don't]. I'd be wary about which Ecuador guide this is too. There's been a lot more work done since the "original" Ridgely guide.

It's important to be exact, also across platforms, which means it's important that same observation keeps same ID on each platform. Thus I would very much appreciate your corrective updates on iNaturalist. Otherwise it's my words against them, and the observation is in limbo with Birdforum and iNatualist being in conflict on same observation.

I don't use iNaturalist. However, threads and posts in Birdforum have unique IDs so surely you can just paste the URL. Forgive me but doing much more is above and beyond what I'm prepared to do.

I should of course have done a better field work and confirmed it's size and nocturnal vocalization, but sometimes you mess up and forget how you arrived at the ID.

I will update image on Opus.

I also don't get this. The key criteria to identify this as a long-tailed potoo are in your second image. What is the dispute?

 

[pbjosh]

I don't purport to be an expert on Potoos at all. I think that they can be very difficult to ID when just seen and not heard. To my eye the bird looks like Common Potoo not Long-tailed. I am going essentially entirely on structure (wing/tail length difference, and overall tail length). Given that there are known morphs and a lot of variation in Common Potoo, and that in general all of the Potoos aside from Rufous seem to be somewhat variable, I would be hesitant to try to ID on plumage details that are still perhaps not definitively understood.

I would also point out that Long-tailed Potoo is not known, as far as I know, from as far south as PN Amboró. While the location at the base of the Andes and a probable elevation around 1000m or so superficially sounds good for the species, I wouldn't know how to know if the habitat is actually still correct. It's a fair ways south of where it's mapped in the recent and generally quite accurate Bolivia field guide. As well, the southern extent of eBird records agrees fairly well with the Bolivia field guide.

I could be mistaken and this could be a Long-tailed Potoo, but I don't see it. If it is a Long-tailed Potoo, it would apparently represent a noteworthy range extension and would merit registering in eBird and contacting Armonia / Sebastian Herzog so they can incorporate the information.

Cheers!

 

[rosmo01]

I don't purport to be an expert on Potoos at all. I think that they can be very difficult to ID when just seen and not heard. To my eye the bird looks like Common Potoo not Long-tailed. I am going essentially entirely on structure (wing/tail length difference, and overall tail length). Given that there are known morphs and a lot of variation in Common Potoo, and that in general all of the Potoos aside from Rufous seem to be somewhat variable, I would be hesitant to try to ID on plumage details that are still perhaps not definitively understood.

I would also point out that Long-tailed Potoo is not known, as far as I know, from as far south as PN Amboró. While the location at the base of the Andes and a probable elevation around 1000m or so superficially sounds good for the species, I wouldn't know how to know if the habitat is actually still correct. It's a fair ways south of where it's mapped in the recent and generally quite accurate Bolivia field guide. As well, the southern extent of eBird records agrees fairly well with the Bolivia field guide.

I could be mistaken and this could be a Long-tailed Potoo, but I don't see it. If it is a Long-tailed Potoo, it would apparently represent a noteworthy range extension and would merit registering in eBird and contacting Armonia / Sebastian Herzog so they can incorporate the information.

Cheers!

Thanks for your input. I've definitely noticed the official range - from xeno-canto and inaturalist to eol and ebird which definitely works against long-tailed.

 

[pbjosh]

It is worth noting that some of those range maps might be derived from each other, so I wouldn't quite take it as 4 data points. I would say that XC makes a good effort to make accurate maps, but they will be working with data such as the Bolivia field guide and eBird as sources.

I would consider it very possible that Long-tailed Potoo has a greater range than currently documented.

But, I don't believe your bird is a Long-tailed Potoo. However, please don't take my assessment of your photos as expert. Potoos are hard, I have never seen Long-tailed Potoo personally and have never really studied photos like this before.

If you really want better feedback try Advanced Bird ID and Neotropical Bird Club pages on FB, or if you know folks like Dan Lane, Alvaro Jaramillo, Sebastian Herzog, etc - asking some of them for input would be worthwhile.

 

[THE_FERN]

It is worth noting that some of those range maps might be derived from each other, so I wouldn't quite take it as 4 data points. I would say that XC makes a good effort to make accurate maps, but they will be working with data such as the Bolivia field guide and eBird as sources.

I would consider it very possible that Long-tailed Potoo has a greater range than currently documented.

But, I don't believe your bird is a Long-tailed Potoo. However, please don't take my assessment of your photos as expert. Potoos are hard, I have never seen Long-tailed Potoo personally and have never really studied photos like this before.

If you really want better feedback try Advanced Bird ID and Neotropical Bird Club pages on FB, or if you know folks like Dan Lane, Alvaro Jaramillo, Sebastian Herzog, etc - asking some of them for input would be worthwhile.

Agree all this.

On range: seems a little odd [if not unprecedented] that long-tailed should be missing from much of southern Bolivia when it's recorded in E Paraguay. I suspect few are venturing away from known locations in Bolivia.

 

[Lisa W]

Hi, just wanted to remind you to include the location in the thread title as per forum rules. Thanks.

 

[rosmo01]

Hi, just wanted to remind you to include the location in the thread title as per forum rules. Thanks.

I don't have edit powers for thread title..