Abstract
In 2014, most parrot aficionados understand well that one of the most personable of all the species of parrots in aviculture is the Caique. They have become very popular as pets and Caique breeders have found them to be excellent parents, willing to breed at around three years of age. Caiques are unique with their white bellies and are easy to house, given their relative small sizes, between 9 to 10 inches and their negligible weight of between 145 to 175 grams, less than 6 ounces, which allows them to be kept as pets in apartments or houses and as breeders, indoors or outside. They are not inexpensive. However, at retail pet bird stores they sell for anywhere from $800 to $1, 100. Obviously, size doesn't matter. They are a superb species.
In the US, and I assume elsewhere outside of South America, there are two largely representative species/two races of Caiques seen in captivity: the Black-headed Caique (Pionites melanocephalia melanocephalia), and the White-bellied or Yellow-thighed Caique (Pionites leucogaster xanthomeria).
The Pionites as a single genus is restricted in its natural distribution to the northern half of South America, mostly in the tropical zone called Amazonia. The countries in South American where most Black-headeds are found include:
Peru, Ecuador, Venezuela, Columbia, the Guianas and parts of Brazil, north of the Amazon River. Moving inland, away from the Atlantic coastline, the Black-headed Caiques start to change appearances, gradually losing the rich orange color to the thighs. Caique populations found near the foothills of the Andes Mountains are black headed with clear yellow thighs. This race is called the Pallid Caique.
If you drop further south from the foothills of the Andes, you are entering an area where there are no major physical obstacles separating the two species (races) of Caiques (eastern Columbia, northeastern Peru and northwestern Brazil). This could be a hybrid zone where only the smaller tributaries of the Amazon River separate the two races. Away from the Andes and back toward the Atlantic on the south side of the Amazon River, there is the more typically seen (in captivity), Whitebellied Caiques, with yellow flanks and legs, mentioned above (P. L xanthomeria). These popular parrots in aviculture inhabit areas south of the Amazon River, including eastern Peru, parts of northern Bolivia and northern Brazil.
As these parrots' populations move deeper into Brazil and farther east back toward the Atlantic side, the nominate race of the White-bellied Caiques (P. L leucogaster), those with green thighs, are in residence. There are relatively few numbers of these White-bellied/Green-thighed-Caiques in captivity because Brazil was never a big exporter of their wildlife. The Yellow-tailed (also with yellow legs) subspecies is found only in the vicinity of northwestern Brazil.
Certainly you have noticed my tendency to vacillate in my descriptions from species and subspecies to races. I, like many others, believe the Black-headed and White-bellied species are races of Caiques within a superspecies (allospecies). We know it is geography and possibly the ecology favored by Caiques that have kept them separate allowing for some differentiation based on head, thigh/legs, and tail color and maybe some slight size differences.
The assumption behind the definition of species is that they could not, or would not interbreed with another species where their ranges overlap. It is known by...