I’ve read and been told many times that our city’s resident pigeons (Columba livia), or “rock doves,” evolved dark pigmentation to blend with the European, North African, Middle Eastern and Central Asian cliff sides where they originally roosted. The transition to a feral life in our gray and sooty concrete, granite, and steel hardscape on another continent was smoothed by this camouflage. Or so the logic went.
One problem with this natural supposition is that for several human generations (and that’s a whole lot of pigeon generations) there were very few predators to act as agents of natural selection. The much trumpeted return of hawks and falcons to New York City is very recent. Numerous paler pigeons and faux white doves were released into the mix too, yet their distinctive patterns breed out rather rapidly.
So what gives?
Recent research published in the Journal of Avian Biology indicates an immune system advantage somehow related to melanin might be at work. A healthy or complimentary immune system is often a key element of sexual attractiveness in many species, including humans. The BBC has more. What strikes me as particularly interesting is there seems to be a possible human parallel for this theory regarding avians. Of course so many tricks deployed by “higher organisms” are old hat to insects and even smaller beasties. Insects damage and entomb microbes using melanin, but according to a researcher in New York, microbes themselves might use melanin for protection from host immune responses!
Let’s hope this means that all those wedding “doves” sent skyward are rushing into the wings of a dark, handsome stranger and not an eager set of talons!
If you love these birds across species lines, who are we to judge? You might enjoy volunteering with the NYC Pigeon Rescue Central!