This bird is actually a natural hybrid between the African Paradise Flycatcher and the Red-bellied Paradise Flycatcher (Terpsiphone viridis x rufiventer).
A hybrid swarm is a population of hybrids that has survived beyond the initial hybrid generation, with interbreeding between hybrid individuals and backcrossing with its parent types. Such populations are highly variable, with the genetic and phenetic characteristics of individuals ranging widely between the two parent types. This bird shows mainly Red-bellied Paradise Flycatcher features but has some black streaking on the belly.

Abuko is a small forest reserve in The Gambia which holds some Savanna woodland and an enclave of very rich moist Gallery forest.
African Paradise Flycatchers prefer drier Savanna woodland whilst the closely related Red-bellied Paradise Flycatcher prefers rain forest and moist Gallery forest. Normally these birds are separated by their habitat preference but at Abuko the species mix, interact and hybridise.