In case you have birded very lengthy, you might be most likely conscious that members of intently associated hen species, when their ranges overlap, typically love one another very a lot, and have infants. Some even do that so typically that pictures of their hybrids will likely be included in hen guidebooks. When this occurs significantly typically, such hybridization processes can lead to solely new species.
Right here in central Mexico, now we have one such case that’s so notable that it has been the topic of a great deal of scientific examine. One current article, “Hybrid zone or hybrid lineage”, refers back to the concern in its subtitle as “Sibley’s basic species conundrum in hybrid Pipilo towhees”. The conundrum in query is the affirmation by the ornithologist Charles G. Sibley, manner again in 1950, that every one Noticed Towhees in western central Mexico are the product of a hybridization gradient between the southwestern Collared Towhee, Pipilo ocai, and the jap Mexican race of the true Noticed Towhee, Pipilo maculatus. (Again then, Sibley used the identify “Purple-eyed Towhee” for what we name Noticed Towhees in the present day.)
I’ve, sadly, not but seen a Collared Towhee, regardless that they supposedly happen in my neck of the woods. Happily, I’ve nice birder buddies; these improbable pictures are by Alberto Lobato and René Valdez. Be aware the white throat patch above a black collar, the orange mohawk crown, the olive again, and the one barely dusky flanks.
In distinction, the basic Noticed Towhee of the western U.S. and jap Mexico has an all-black head, a black again with vibrant white spots, and orange flanks. This picture is mine, from the central Californian coast.
Our native variant of the Noticed Towhee, presently referred to as the (Olive-backed) Noticed Towhee, seems completely different than each. However upon learning the above pictures of Collared Towhees, I can see that Sibley might properly have been proper. Our birds have the black head and reddish flanks of the basic Noticed Towhee, and the spotless olive again of the Collared Towhee. So are they a subspecies, or a hybrid intergrade?
To make issues much more difficult, our presumably hybrid Olive-backed Noticed Towhees can hybridize even additional with the Collared Towhee. Till not too long ago, I had solely seen a number of examples of this. All had been distinguished by the delicate variations of a extra greenish again of the top, barely lighter flanks, and a touch of the Collared Towhee’s reddish crown.
The rationale I’m writing about this topic now, is that simply this week I lastly noticed my private holy grail of hybrid towhees. The lighting didn’t enable me to see the colour of this hen’s crown. And it by no means did give us the full-frontal view that might have been so useful. However my few pictures left little question; this hen had a black coloration, a white throat patch, and only a trace of a white line above the eyes. This was a transparent hybrid Pipilo maculatus x ocai. Actually, if Sibley’s concept from way back is right, this hen might properly be referred to as a hybrid hybrid.
I ought to most likely add a private confession on the finish of this submit. Twice, in 2019 and 2022, I complained on this website about having to make use of the identify Noticed Towhee for our domestically spotless birds. I’ve even begged, with no scientific foundation, for a taxonomic cut up, in the event that they wouldn’t change that identify. I’ve accused bird-namers of being biased to their United States expertise of birds. (Admittedly, that’s nonetheless true for the Summer time Tanager, which we solely see right here within the winter.) However my analysis for this submit has proven me that this drawback could also be rather more difficult. Actually, when you transfer east from Morelia in direction of lands occupied by conventional Noticed Towhees in jap Mexico, you’ll apparently discover Olive-backed Noticed Towhees similar to mine… however with gentle spots on their wings, rising ever clearer as you progress in direction of the rising solar.
I humble myself earlier than the complexities of the pure world.
