Date: 8/18/25 8:05 pm From: Robert O'Brien <baro...> Subject: Re: [BIRDWG01] Neotropic vs. Double-crested Cormorant
And I promise not to harass the Listserver any more; after this last
observations from the eBird map I included above. Most hybrids are
reported far away from the locations where they are most expected. That
is, they are being overlooked among all the individual, abundant species.
And, further, it is likely that some (many?) eBird reviewers are not making
such reports public (due to uncertainty in the ID) so that the actual
number of far flung hybrids is even higher than reported. So, unless
a. All these reports are erroneous or
b. There is likely a much larger proportion of hybrids in the hybrid zones
than is currently documented. Or
c. Such hybrids have a strange propensity for dispersal to distant
places. This seems unlikely.
Bob OBrien Portland
On Mon, Aug 18, 2025 at 7:28 PM Robert O'Brien <baro...> wrote:
> These eBurd reports notwithstanding, there are definitely some out there.
> Here is what my friend ChatGPT came up with. Bob OBrien Portland
>
> -
>
> *Wakodahatchee Wetlands, Delray Beach, Palm Beach Co., Florida* —
> repeated, well-documented mixed pairings inside the Double-crested colony:
> -
>
> A female *Neotropic Cormorant* *“paired with a Double-crested
> Cormorant”* and was *seen copulating* on *2 Jan 2016*. Florida
> Ornithological Society Records Committee (FOSRC) “Twenty-sixth Report.” Internet
> Archive
> <https://archive.org/stream/floridafieldnat46flor/floridafieldnat46flor_djvu.txt?<utm_source...> > -
>
> Earlier, at the same site, the *Neotropic* *“formed a pair bond
> with a male Double-crested Cormorant, copulated with him, and successfully
> reared young.”* FOSRC “Twenty-fourth Report.”
> -
>
> Additional FOSRC language for this site calls out a *mixed-pair
> nest with ongoing incubation* in 2015. FOSRC “Twenty-fifth Report.” Digital
> Commons USF
> <https://digitalcommons.usf.edu/cgi/viewcontent.cgi?article=2332&context=ffn&<utm_source...> > -
>
> A summary piece by Kenn Kaufman also notes that since *2012* one or
> more *Neotropics joined the Delray Beach DCCO colony and interbred*,
> creating hybrids there. DigitalCommons
> <https://digitalcommons.unl.edu/cgi/viewcontent.cgi?article=1322&context=usfwspubs&<utm_source...> >
> If you want the exact passages (page context) from the FFN/FOSRC reports,
> I can pull those out for you—but the three committee reports above
> explicitly document the *pair bond*, *copulation*, and *mixed-pair
> nesting* events at Wakodahatchee.
>
> Yes I do.
> *Summary Table*
> Site / Source Observation Details
> *FOSRC 23rd Report (2015)* Adult Neotropic paired with Double-crested →
> hatched 4 young, fledged 2
> *FOSRC 26th Report (2018)* Female Neotropic “paired with” Double-crested
> Cormorant—explicit pairing confirmed
> *Birding Blog (Nemesisbird)* Adult Neotropic confirmed breeding with
> either Double-crested or hybrid mate
> *Tropical Audubon / Birds of S. Florida* Adult Neotropics on nests and
> apparently hybridizing since 2012
> ------------------------------
> Broad Takeaway
>
> The *only well-documented, explicit examples* of *mixed pairs* (adult
> Neotropic × adult Double-crested Cormorants) being *seen together and
> reproducing* come from *Wakodahatchee Wetlands* in Palm Beach County:
>
>
> -
>
> *2015 (FOSRC 23):* Verified mixed pair hatched and fledged offspring.
> -
>
> *2018 (FOSRC 26):* Explicit observation of pairing behavior.
> -
>
> *Additional corroborative birding sources* reinforce these occurrences
> since 2012.
>
>
> On Mon, Aug 18, 2025 at 6:59 PM Robert O'Brien <baro...> wrote:
>
>> And then there are the hybrids. One reported even so far away as here in
>> Portland Oregon. Note I said 'reported'.
>> Bob OBrien Portland.
>> [image: image.png]
>>
>> On Sat, Aug 16, 2025 at 6:10 AM Marcel Gahbauer <
>> <marcel...> wrote:
>>
>>> Hi everyone,
>>>
>>> I'm curious for feedback on an unusual cormorant observation I had
>>> earlier this week.
>>>
>>> I was attending an event on private property adjacent to Lake Ontario,
>>> when my 8-year-old son came to tell me there was a cormorant 'trapped' in
>>> the rocks along the shore. It wasn't trapped as such - but it was just
>>> floating there in a small space between rocks, and occasionally being
>>> pushed into them by the waves. It looked like one eye was damaged or
>>> diseased, and locals told me some cormorants had washed up recently and
>>> were presumed to have died from botulism, so my initial thoughts were
>>> focused on the health of the bird more than its ID (given that the only
>>> regularly occurring species in Ontario is Double-crested).
>>>
>>> However, upon sharing a few photos with friends, the suggestion was
>>> raised that it could be a juvenile Neotropic Cormorant, given the
>>> proportionately long tail, relatively darker upper breast, and generally
>>> sleek shape. In retrospect, it was relatively small - I didn't notice that
>>> at the time given the circumstances but I was as close as 5 m and so it
>>> seemed like a large bird based on proximity more than reality perhaps. On
>>> the other hand, the bill still looks to me quite sturdy and more like that
>>> of a Double-crested Cormorant.
>>>
>>> Although I've seen Neotropic Cormorant once previously in Ontario (more
>>> conveniently among a group of Double-crested) and a few times in its
>>> regular range, I don't have enough experience to be confident in resolving
>>> these seemingly conflicting aspects of ID, and would welcome any insights.
>>> Photos are posted in my eBird report at
>>> https://ebird.org/checklist/S267572991 >>>
>>> Thanks!
>>>
>>> Marcel Gahbauer
>>> Ottawa, Ontario
>>> <marcel...><mailto:<marcel...> >>>
>>> Archives: https://listserv.ksu.edu/birdwg01.html >>>
>>
