Juvenile Neotropic Comorant? Sumner County, Tennessee, 3rd September 2020 (1 Viewer)

[NorthernKeys]

Is this a juvenile Neotropic Cormorant? Found on the morning of 3rd September and the afternoon before at Old Hickory Dam in Sumner County, Tennessee. It was sitting in the same spot both times, on the bank of the river near the dam with no other cormorants near by.

I believe it could be a Neotropic Cormorant over a Double-crested Cormorant due to the overall browner colour, absence of orange lores, angle of gular pouch, presence of white border around gular pouch, pointy covert feathers, and proportionally long tail. It appears its tail may be wedge shaped too, but it's hard to tell from the angle in the photos.

Compared to a confirmed sighting of a Neotropic Cormorant in Davidson County, Tennessee from last year, this cormorant looks nearly identical. Additionally, it looks very similar to a current confirmed Neotropic Cormorant in Cocke County, Tennessee.

I posted this on Reddit and in a Tennessee Birding Facebook group previously, and while a couple of people have agreed it may be a Neotropic, the idea of it being a Neotropic x Double-crested hybrid was also raised. I believe this not to be the case, since what little information about hybrids I've found suggests that one would not have the white border around the gular pouch and may retain the orange lores. However, I'm certainly still open to it being a possibility.

Thanks in advance! |=)|

 

[kevinsl06]

Welcome to Birdforum also!

 

[njlarsen]

I do not quite like the shape of the gular pouch, compare with https://www.birdforum.net/opus/Neotropic_Cormorant

Whether this means it could be an individual deviating from the norm or a hybrid I am not sure.

Welcome to birdforum

Niels

 

[NorthernKeys]

Thank you both for the warm welcomes!

I do not quite like the shape of the gular pouch, compare with https://www.birdforum.net/opus/Neotropic_Cormorant

Whether this means it could be an individual deviating from the norm or a hybrid I am not sure.

Welcome to birdforum

Niels

The gular pouch seemed to be one of the main points of contention when I posted it in the local Facebook group too. I'm not sure how much variation there would typically be between individuals, but I don't feel like the gular pouch would be quite what I expect from a Double-crested Cormorant either.

 

[njlarsen]

Thank you both for the warm welcomes!



The gular pouch seemed to be one of the main points of contention when I posted it in the local Facebook group too. I'm not sure how much variation there would typically be between individuals, but I don't feel like the gular pouch would be quite what I expect from a Double-crested Cormorant either.

Definitely not. If it has genes from a DC Cormorant it would be as a hybrid I would think.

Niels

 

[njlarsen]

you may have found these two resources already:
http://azfo.org/journal/NECO_2008.html
https://static1.squarespace.com/sta...be4b07baccbccbb7a/1437960219306/Cormorant.pdf

Niels

 

[NorthernKeys]

you may have found these two resources already:
http://azfo.org/journal/NECO_2008.html
https://static1.squarespace.com/sta...be4b07baccbccbb7a/1437960219306/Cormorant.pdf

Niels

Thank you for the information. I had found the PDF source recently, but the other source is new to me.

Looking at these sources and matching up the information with this cormorant, I believe it could still be the case that it's a Neotropic, due to the proportionally shorter bill, as mentioned on the PDF, and the dark supra-loral area and consistent brown colouring, as mentioned in the other source, although it's hard to tell the former from my photos whether that's due to feathering or not.

The proportional size of the tail is harder to tell, but when this cormorant is stood upright, as in my third picture, it looks like it extends further than the feet. It looks like it could be more wedge-shaped too, but again, that's hard to tell from my photos due to the angle.

Of course, these observations could be my own wishful thinking, but it seems to match up with Neotropic better for the most part. What do you think about these observations?

 

[njlarsen]

I have mostly concentrated on the gular patch. I looked at the PDF again. The second to last image shows a bird with yellow lores and gular patch similar in shape to the one you have photographed. I would say either both are good Neotr. C or both are hybrids. And I am not enough of an expert to even know if hybridization is a serious issue for these species.

Niels

 

[njlarsen]

Seems that there is possibilities especially in eastern US: http://birdhybrids.blogspot.com/2014/06/neoptropic-cormorant-x-double-crested_2.html

Niels

 

[NorthernKeys]

It's a shame there seems to be so little information on hybridisation - it seems like an interesting topic to look into.

For the time being though, one thing I've noticed while looking through the source you just linked to is that none of the hybrids pictured appear to have the white feathering below the gular pouch. However, that white feathering is present in the cormorant that I photographed.

This appears to be consistent with other photos/reports of hybrids, such as these:

https://ebird.org/checklist/S65228125

https://www.flickr.com/photos/tony_...ryN-dR4bAs-dQuVBd-5dV83H-5dV2Rr-5dV7UR-5dZsyj

They do appear to be adults though, so I'm not sure what kind of variation in juveniles to expect.

 

[njlarsen]

Do you have access to Birds of the World? there is a discussion of when the white bordering the gular pouch and other interesting feather characteristics occur, with which it should be possible to accurately age your bird.

Niels

 

[NorthernKeys]

Do you have access to Birds of the World? there is a discussion of when the white bordering the gular pouch and other interesting feather characteristics occur, with which it should be possible to accurately age your bird.

Niels

Luckily I'd just subscribed to that website recently! |=)|

After reading through that, I feel like this cormorant matches best with the First Basic Plumage. However, I notice it mentions "Lacks white-bordered gular pouch acquired later" as part of this description. Perhaps that could be referring to the white feathering seen in adult Neotropic Cormorants?

That said, it looks like this cormorant matches up with the photographs accompanying this description, including the white bordering the gular pouch.

I read some information about the plumage for Double-crested Cormorant too, and I feel like I would expect the First Basic Plumage to be lighter than this cormorant.

The Second Basic Plumage for both cormorants suggests that there may be black feathers mixed in with the brown, and as far as I could tell, there are no areas mixed with black feathers on this cormorant.