Resplendent Quetzal - a peculiar tail!

To some a deity or a deity's messanger, to some a national bird and even a currency, to others a source of wonder, the Resplendent Quetzal needs no introduction. Quetzals are a grouping of 6 species in two genera within the trogon family (Trogonidae): Eared Quetzal, Pavonine Quetzal, Golden-headed Quetzal, White-tipped Quetzal, Crested Quetzal and Resplendent Quetzal. Resplendent Quetzal is the only Mesoamerican quetzal species, with Eared Quetzal being North American and the others being South American. Resplendent Quetzal is by far the most famous for the male’s enormous tail that can be >75cm in length (this photo is of the costaricensis subspecies that has a slightly shorter tail than the nominate… believe it or not!). The funky head feathers and sickle-shaped wing coverts set against the waxy red belly add to the splendour. Resplendent Quetzal is not the only species in the world with a long tail but it is rather unique… Can you spot what is so unusual about the tail? Click on the photo to enlarge.

If you cannot figure out what is special about the tail in the above photo, this second photo may help:

If you still need help, notice how the tail feathers are black and normal length (the undertail coverts are white) and the long streamers fall over top of them. In short, it is NOT the tail feathers proper (the rectrices) but rather the uppertail coverts that are elongated. Many birds have long tails derived from elongated tail feathers but having elongated uppertail coverts to this extent is highly unusual. Coverts form the function of “covering” and creating the smooth surface so important for streamlining. Uppertail coverts cover the base of the tail so that the tail is more aerodynamic. Having a covert longer that the feathers it is supposed to be covering is quite unusual. There are four elongated uppertail coverts: two that are long and two that are extremely long!