Rare bird: Neotropic Cormorant at Lake Cuyamaca

First found on April 4th, 2019 by Jim Pawlicki, two Neotropic Cormorants were at Lake Cuyamaca for several days. I was able to visit on April 7th and get the photos presented here.

From left to right: Double-crested Cormorant, immature Neotropic Cormorant, 2 more Double-crested Cormorants, 

and adult Neotropic Cormorant. April 7, 2019. Lake Cuyamaca, California.

I'm not sure I would have identified these birds if I didn't know they were there. Oh, I would have had I really looked at them. But I don't think I would have bothered looking closely at cormorants in the mountains! I would have counted the lumps as Double-crested, added them to eBird, and moved on. It's all about expectation. There are a couple of photos here of birds isolated that certainly would have broken through my expectation bias had I seen them--a bird only 2/3 the size, but perhaps only 1/4 the bulk of the Double-crested Cormorants.

Here are San Diego records of Neotropic Cormorant (from eBird photos):
1) October 12 to December 6, 2014 Lake O'Neill, Camp Pendleton.
2) October 3 to November 26, 2015 Lake O'Neill, Camp Pendleton (presumed same individual as above).
3) October 16 to November 2, 2016 Lake O'Neill, Camp Pendleton (presumed same individual as above).
4) March 6, 2017 Lower Otay Reservoir.
5) April 4, 2019 to April 9, 2019 Lake Cuyamaca.

So this is apparently the 5th record, but only the 3rd and 4th different individuals. October to April, with Double-crested Cormorants, anywhere on fresh water. You can bet I'll be more aware going forward. I suspect I'm not the only one.

This bird was quite distant and the low light made photography difficult. I ended up taking about 500 frames of the birds, changing settings constantly, in order to get these pics. You can click on any of the photos to bring up a larger size.

The adult Neotropic Cormorant on the right with wings open shows the characteristic small orange throat pouch

 shaped as a sharp point outlined with white feathers (especially on the bottom).

An adult Double-crested Cormorant (right, wings open) dwarfs the adult Neotropic Cormorant (left).

The size difference is obvious, but the shape of the throat pouch is easily seen and compared 

(pointed on Neotropic, left; rounded or squared on Double-crested Cormorant, right).

Interestingly, there were two Neotropic Cormorants together, an adult and apparent immature. The immature bird presented some problem as it appeared much more pale and faded than typical. There was some hesitancy about this pale second bird. Eventually, though, the "hybrid hypothesis" for this second bird was dismissed. Apparently, rarely, immature Neotropic Cormorants can be this pale.

Below are photos specifically of this pale bird. The size and throat pouch shape match those of the adult bird. Again, you can click on the photos to bring up a larger view.

Click to enlarge. Compare the yellow throat pouches of the two immature birds together. 

Double-crested (swimming) has a broad throat pouch that also encircles the eye with yellow skin.

The Neotropic Cormorant (3rd from right, wings open) has a pointed throat pouch restricted to the lower face.