Despite their first-glance resemblance to the Black-Masked Lovebird, the Black-Cheeked Lovebird is, in fact, an entirely different species and if anything it is more closely related to the Nyasa Lovebird than the Masked. Like the Nyasa, the Black-Cheeked lovebird is an endangered species, ranking as threatened/vulnerable rather than near-threatened like the Nyasa. Black-Cheeked lovebirds are one of the more docile species of lovebird.
Like the Nyasa, the Black-Cheeked is smaller than the Fischer's, Masked, and Peachface, averaging out at about five to five and a half inches long. Unlike the Masks, they have only black and brown/black cheeks, with the tops and backs of their heads being shades of green. The yellow/orange on their necks, rather than being a full collar, is only a little dab beneath their beaks known as a bib. Like the Nyasa, their beaks are red fading-to-pink at the base, and they have the white eye-ring.
Despite the fact hat they are relatively easy breeders, Black-Cheeks are unusual in captivity, partially due to the fact that they are slightly endangered, but also because for a long while nobody thought to breed them as they are only a recently established breed. Black-Cheeks are not as hardy as other, more popular, lovebird species, suffering from low fertility and a proneness to illness. This is most likely due to rampant inbreeding in the small pool of available stock.
Like the Nyasa Lovebird, Black-Cheeks are bred for purity, rather than mutation, since the species is so hard to come by. There are no true Black-Cheeked Lovebird mutations, and the few available on the market are the resultant hybridizations of breeding with Masks.