The Black-collared Lovebird (A. swindernianus) occurs in two to four disjunct populations in West and Central Africa, where it inhabits lowland evergreen rainforest, both primary and secondary, usually below 700 m but reported up to 1800 m in Uganda. Other than female Grey-headed Lovebirds, Black-collared Lovebirds are the only lovebirds with green heads. The Red-faced Lovebird, which has a partially overlapping range, has a red bill (not blackish as in the Black-collared Lovebird) and no collar. Black-collared Lovebirds are generally encountered in small flocks flying swiftly over the forest canopy. They are quite shy and rarely encountered near ground level. They appear to feed largely on Ficus fig seeds, but also take other seeds and small fruits, as well as adult and larval insects.
(Collar 1997 and references therein; Juniper and Parr 1998 and references therein)