In my experience with the species in Florida, I can confirm that there is a decent range of head colors present in the population there. Among the individuals I have photographed are phenotypes ranging from pure Gray-headed to what could potentially be construed as intermediate between that species and what today is referred to as Western Swamphen (Porphyrio porphyrio) of the Mediterranean basin (though the specifics are speculation on my part). A similar darker and more contrasty phenotype is apparently also exhibited by members of the Gray-headed group from the Caucasus region of west-central Asia, for what it’s worth.
Furthermore, the Florida population was subject to a decently thorough analysis shortly after its establishment (Pranty, Bill, Kim Schnitzius, Kevin Schnitzius, and Helen W. Lovell. 2000. Discovery, distribution, and origin of the purple swamphen (Porphyrio porphyrio) in Florida.' Florida Field Naturalist 28: 1–11) in which possible sources of origin are discussed. The authors were able to locate two separate nearby aviculturists who stocked the species, and though the exact taxonomic assignments to subspecies group of the captive stocks in question were apparently not made available at the time, the article mentions that even at this early date some individuals in the feral population exhibited plumage characteristics (namely blue heads and more saturated neck and body plumage) outside of the phenotype we have come to expect of the Gray-headed group. My interpretation of this information is that the founding population had some plumage variability from the very beginning, which may well have been augmented through interbreeding with later escapees that exhibited non Gray-headed phenotypes irrespective of their exact geographic origins.
In summary, I’m not certain we can point to a really bright individual and say with confidence that it came from somewhere other than the feral Florida population. That being said, only by knowing the exact genetics of this individual can we make anything of it more than speculation.
> On Oct 27, 2018, at 4:47 PM, Derb Carter <derbc...> wrote:
> Caveat that I have not researched the various Swamphens. The Gray-headed is the one reported from Florida, and as the name says is supposed to have a gray head. There are dozens of photos of Swamphens in Florida on ebird checklists. If you scan them head color in adults with red bills ranges from mostly gray to some gray to light blue to deep blue. Check it out if you are interested on ebird checklists for the hotspot: storm water treatment area 5/6 Hendry County Florida. Be sure to get to the photo of reported Gray-headed Swamphens on November 18, 2017 with a deep blue head and no gray. Again, I don't what this means, only what I see in photos.
> Derb Carter