Archive for Hybrids and introgressants
Today marks the 146th birthday of Allan Brooks, the Anglo-Canadian painter and ornithologist. One of the most widely traveled collectors of his (or any other) day, Brooks shot and sketched birds from Ottawa to Auckland and most places in between.
In the hand the bird proved to be about the size of a male Yellow-headed Blackbird…. iris dark brown… entire plumage black, slightly glossed with bluish purple, wings and tail more greenish… tail with thirteen rectrices, strongly graduated… quite flat without trace of plication….
Before Law collected the bird, it had
walked about sedately, frequently posing with its head thrown back, the bill pointing straight up and the neck slightly extended.
Brooks sent the specimen east to the Smithsonian, where the skin and trunk skeleton are now USNM 313651 and 322691. After examining the bird, Charles W. Richmond was of the opinion that it was most likely “a very new species” of grackle; Alexander Wetmore agreed. “Neither,” Brooks adds, “considered it to be a hybrid.”
Today, no one really believes that Brooks and Law discovered a new blackbird on that spring day in Mammoth. Jaramillo and Burke — Canadians around every corner here! — report that an analysis of the specimen’s mitochondrial DNA identified its female parent as a grackle of one species or another; more DNA was removed from the bird’s foot in 2004, but I don’t know what the results, if any, were of that study.
The BNA account for the great-tailed grackle identifies the Arizona bird as a hybrid between that species and the red-winged blackbird, an unexpected pairing given the care female great-tails take to avoid mating with even the much more closely related, much more similar boat-tailed grackles.
Whatever it was, whatever it is, the Pinal County nondescript remains testimony to the good eye of Major Allan Brooks. And to the good aim of Gene Law, of course.
It happens two or three times a day most days. Someone ‘posts’ or sends me a photo of a mystery waterfowl, and I respond, almost without the need to think, in one of three ways:
This is a domestic mallard.
This is a domestic muscovy duck.
This is an apparent hybrid between the mallard and the muscovy duck.
Ninety years ago today, on November 1, 1924, Joseph P. Bell shot two unknown birds in Wallen County, Texas. He showed one of them to Robert B. Lawrence of Houston, who
identified it as the so called “Violet Duck, Anas maxima” of Gosse, supposed to be a cross between the Mallard and Muscovy.
The bird Lawrence examined weighed almost eight pounds — three times the size of a normal wild mallard drake.
This hybrid combination is a frequent one, thanks to the abundance of both species in captivity and to their unbounded concupiscence. The snazzy bird in the center of the photograph above is of known parentage, and he shows all the classic signs of a hybrid: the mallard-like head and neck pattern, the glossy green back and rump, the long tail of his muscovy forebear.
And he’s enormous.
If ever I knew it, I’d entirely forgot that this mix had been assigned a scientific name — and more than once, at that. Three quarters of a century before Bell took to the field with dog and gun, Philip Henry Gosse described a “magnificent Duck” taken near Savanna le Mar, Jamaica. No less a leading light than George Robert Gray had already affirmed that he thought the bird a hybrid, but Gosse was unconvinced: the local gunners were familiar with ducks of this sort, and had been for nearly a hundred years, suggesting that this was no mere incidental crossbreed but a new species, the green-backed mallard, Anas maxima.
Gosse described his maxima in 1847, in disregard not only of Gray’s opinion but of Charles Lucian Bonaparte’s observations, made years before in the Iconografia della fauna italica, that the muscovy duck
freely breeds with mallards, wild or domestic, producing the claimed species purpureo-viridis of Schinz,
quite likely hybrids of those two species, but I maintain some doubt in this matter, since I believe that the hybrids of these ducks produced in captivity have a small bare area between the eye and the bill which is not present in Schinz’s bird.
nearly twenty years ago I made the journey to Lausanne expressly to examine Schinz’s Anas purpureo-viridis, and not satisfied with just rejecting the name, as applying to a h y b r i d of the muscovy and the mallard, I continued to search out this bird everywhere and in all its forms, from Lake Trasimeno, where it was observed virtually on my doorstep, all the way to Asia and America….
without finding any reason to believe that the bird was anything but a hybrid.
In 1896, half a century after Gosse’s claimed discovery, André Suchetet laid out all the evidence to do with the existence and status of Anas maxima. His review of specimens sent from all over Europe, along with colored engravings of the bird, convinced him that
we are dealing here with birds escaped from captivity, but when they were killed in fact living in a feral state in a wide range of countries, some on the lakes of Switzerland and Lombardy, others along the rivers of Silesia, Russia and France, and, finally, one from a pond in Belgium.
The earliest specimen of which Suchetet was aware was one taken on Lake Geneva in April 1815; there were also American skins, including two males held in the collections of the Smithsonian. His investigation led him to affirm that the hybrid origin of all these mysterious ducks from such far-flung places was at the very least “probable.”
That hasn’t stopped us from being confused every once in a while anyway. But not as confused as these miscegenating ducks, fortunately.