What Kind of Bird is Big Bird?

What’s 8.5-feet tall with bulbous, imploring eyes; brilliant, sunny plumage; and wings, but can’t fly?
Okay, okay, so that was easy. Big Bird. But just what kind of bird is Big Bird, if any? Mike Dickison thinks he’s got the yellow fellow pegged.
Years ago as a PhD student studying the evolution of giant flightless birds, Dickison realized that this particularly statuesque and permanently grounded avi-creature had escaped detailed species analysis. Curious to learn more, Dickison compared some of BB’s defining traits to other birds’. There were key differences. “It had some unique anatomical features,” says Dickison in a narrated slideshow first presented in Christchurch, New Zealand in May and recently made available online. Among them: an elongated neck, a modified wing with three fingers, an enlarged abdomen, and an unusual reduction in its foot. In contrast, flightless birds that might seem closely related to the yellow guy—namely, ostriches, emus, and cassowaries—have no wings at all. They’ve also got short beaks. Grandicrocavis viasesamensis,** as Dickison dubbed his subject, sports a long honker.
Hmm, okay. So do historical descriptions say anything about G. viasesamensis? Apparently yes—that it was an "eight-and-a-half foot canary” (doped up on AGH?)*. Nay! says Dickison. Such a description is implausible, he explains in the slideshow, because “songbirds almost never go flightless and scarcely increase in size.”
Such insight led Dickison to another type of bird with a long beak and neck: the crane. Fossil records reveal two types of giant flightless cranes, namely the Cuban crane and the Bermuda crane, which once lived on the islands they’re named after. Meanwhile, reasoned Dickison, living cranes also exhibit features similar to the feathery tall drink of (birdbath) water in question—and specifically, the whooping crane. Why whoopers? “The juvenile plumage of the whooping crane has a golden orange fluffy character which is extremely similar to the adult plumage of Grandicrocavis viasesamensis," observes Dickison.
Okay, so Big Bird is some kind of giant flightless crane, and one that lives in…New York City? Well, consider the following: As many know, and as its name reflects, G. Viasesamensis resides on Sesame Street, which is in turn located in Long Island. Considering that flightless birds have been known to evolve on islands—take the two extinct cranes from Cuba and Bermuda—it isn’t so hard to imagine a scenario “millions of years ago when flocks of flightless cranes roamed the wilds of Long Island before humans arrived,” says Dickison, “[after which people] banished them to the recesses of an urban situation where they hang on today.”
Of course, adds Dickison, what would confirm Big Bird’s ties to whoopers and flightless cranes of yore would be a DNA test. But then again, I’m guessing Carroll Spinney might not be so keen on that.
*Avian Growth Hormone (disclaimer: author has no knowledge of the finer aspects of this substance)
**from grandi, meaning large; crocus for yellow; avis for bird)