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. Sound Flying flocks make a distinct sound due to the many wing beats. After arriving at the roost or nest site, birds keep moving around and make a lot of noise for about half an hour before settling in. Both males and females call. The male sings in short bursts, starting with some chatter, followed by a warbling tweedle-toodle-tweedle. Distribution and habitat The red-billed quelea is mostly found in tropical and subtropical areas with a seasonal semi-arid climate, resulting in dry thornbush grassland, including the Sahel, and its distribution covers most of sub-Saharan Africa. It avoids forests, however, including miombo woodlands and rainforests such as those in central Africa, and is generally absent from western parts of South Africa and arid coastal regions of Namibia and Angola. It was introduced to the island of Réunion in 2000. Occasionally, it can be found as high as above sea-level, but mostly resides below . It visits agricultural areas, where it feeds on cereal crops, although it is thought to prefer seeds of wild annual grasses. It needs to drink daily and can only be found within about distance of the nearest body of water. It is found in wet habitats, congregating at the shores of waterbodies, such as Lake Ngami, during flooding. It needs shrubs, reeds or trees to nest and roost. Red-billed queleas migrate seasonally over long distances in anticipation of the availability of their main natural food source, seeds of annual grasses. The presence of these grass seeds is the result of the beginning of rains weeks earlier, and the rainfall varies in a seasonal geographic pattern. The temporarily wet areas do not form a single zone that periodically moves back and forth across the entirety of Sub-Saharan Africa, but rather consist of five or six regions, within which the wet areas "move" or "jump". Red-billed quelea populations