Red-billed quelea far above the bill, and the underparts may have a pink wash. There is much variability within subspecies, and some birds cannot be ascribed to a subspecies based on outward appearance alone. Because of interbreeding, specimens intermediate between subspecies may occur where the ranges of the subspecies overlap, such as at Lake Chad. The female pin-tailed whydah could be mistaken for the red-billed quelea in non-breeding plumage, since both are sparrow-like birds with conical red-coloured bills, but the whydah has a whitish brow between a black stripe through the eye and a black stripe above. Flying flocks make a distinct
Red-billed quelea from northern and central Sudan and central Ethiopia in May and June, to breed in southern Sudan, South Sudan, southern Ethiopia and northern Kenya, moving back north from August to October. In southern Africa, the total population of the subspecies "Q. quelea lathamii" in October converges on the Zimbabwean Highveld. In November, part of the population migrates to the northwest to northwestern Angola, while the remainder migrates to the southeast to southern Mozambique and eastern South-Africa, but no proof has been found that these migration cohorts are genetically or morphologically divergent. The red-billed quelea is regarded as the most numerous