Join/Renew (2022 Dues)
News from https://groups.io/g/SanDiegoRegionBirding

Del Mar cormorant ID problems

Del Mar cormorant ID problems
By – 1:51 pm

As many of you know, there has been a cormorant (or two??) of interest, roosting on the power lines near the mouth of San Dieguito Lagoon in Del Mar with a group of Double-cresteds, since late June. There are many eBird reports with photos of “the” bird from back then through today. Look at the “Species Maps” page in eBird for the complete selection (all included under either the “San Dieguito Lagoon-Southwest” or “Del Mar Public Works” hot-spots). When it was first discovered by Dan King and over the next few days, the photos looked OK for an adult Neotropic Cormorant. But then just a few days later, some folks mentioned how quickly it seemed to have lost most of the bold white border to the gular–and, in fact, photos at the end of June and during the first week of July show variably a problematic bird with a very weak, partial pale rear-gular border, and some with a somewhat bolder, but still somewhat weaker version of what the bird looked like in late June but still OK for Neotropic. But starting around then, and then continuing until now in early August, virtually all the photos show a somewhat problematic bird. I say “problematic” as the bird appears BARELY smaller/slimmer and “longer”-tailed than the adjoining Double-cresteds. I mean, you have to squint really, really hard to note any such differences, whereas a typical Neotropic would stand out like a true sore thumb amongst the D-c’s. Also, the gular is rather bright orangey, rather than duller orange or yellow-orange. The gular does come to point in the rear, but it also does so in some Double-cresteds. AND, the bird indeed does show a small, oblong patch of orange in the lores. One needs a scope to see this small loral patch. (As an aside: As an eBird reviewer, it can be a bit disquieting to see written details which mention the bird having totally dark lores but then the photos in the same checklist in fact showing the small patch of orange.)

For additional photos of “the” current bird, see my list for today (https://ebird.org/checklist/S116334210) entered as “cormorant sp.” And compare these photos from those of the past few days and the past several weeks.

So, is this bird just an odd Double-crested, or is it a hybrid? And when did a reasonable looking adult Neotropic Cormorant “morph” into a problematic bird?

–Paul Lehman, San Diego