What kind of cormorants?

What kind of cormorants are these? They were taken in Waco, TX.

And how do you tell the difference in double-crested and neotropic?

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Oh, nice! The short bill and (especially) the white V bordering the rear of the bare facial skin make these Neotropic Cormorants. Double-crested Cormorants are best told by their much brighter yellow (or even orangey-yellow) facial skin; they also have longer bills, longer wings and shorter tails. Neotropic's long tail is especially noticeable in flight.

Seems you've hit a pretty good find. My field guide only ranges them through southern Texas!

Badams says the photo was taken in Waco; it's within their range (according to my Sibley guide anyway).

Interesting point! Sibley's guide, which is my normal first port of call, agrees with you, as does the map here: http://www.birds.corne​ll.edu …tropic_Cormoran​t_dtl.html

However the map in Jonathan Alderfer's excellent National Geographic Complete Birds of North America shows them covering most of the eastern half of the state (a bit more extensively in the breeding season than outside) and says this about the range:

"Breeding: In main US range (coastal TX and southwestern LA) found in coastal bays, inlets and freshwater lakes and ponds. More local inland on reservoirs, lakes and rivers; breeds in southern NM and possibly OK. Non-breeding: Northeast and north-central TX birds withdraw south in winter."

I know they at least migrate through southeastern Oklahoma as well. I'm on a bird listserv and they report neotropic ones every now and then.

I've also got a nice little series of one of them trying to get a mudcat down.