Non-breeding birds have light underparts, striped brown upper parts, yellow-edged flight feathers and a reddish bill.

Breeding males have a black (or rarely white) facial mask, surrounded by a purplish, pinkish, rusty or yellowish wash on the head and breast.

It constructs oval roofed nests woven from strips of grass hanging from thorny branches, sugar cane or reeds.

[5] He incorrectly mentioned that it originated in India, probably because ships from the East Indies picked up birds when visiting the African coast during their return voyage to Europe.

[4] He called the bird Moineau à bec rouge du Senegal in French and Passer senegalensis erythrorynchos in Latin, both meaning "red-billed Senegalese sparrow".

Q. quelea spoliator was described by Phillip Clancey in 1960 on the basis of more greyish nonbreeding plumage of populations of wetter habitats of northeastern South Africa, Eswatini and southern Mozambique.

This colouring may only reach the lower throat or extend along the belly, with the rest of the underparts light brown or whitish with some dark stripes.

Outside the breeding season, the male lacks bright colours; it has a grey-brown head with dark streaks, whitish chin and throat, and a faint light stripe above the eyes.

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.

[2] 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.

[7][2] 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.

[7] In Nigeria, the nominate subspecies generally travels 300–600 km (190–370 mi) southwards during the start of the rains in the north during June and July, when the grass seed germinates, and is no longer eaten by the queleas.

After about six weeks, the birds migrate northwards to find a suitable breeding area, nurture a generation, and then repeat this sequence moving further north.

[23] The red-billed quelea is regarded as the most numerous undomesticated bird on earth, with the total post-breeding population sometimes peaking at an estimated 1.5 billion individuals.

The consumption of a lot of food with a high energy content is needed for the queleas to gain enough fat to allow migration to new feeding areas.

[24] Small groups of red-billed queleas often mix with different weaver birds (Ploceus) and bishops (Euplectes), and in western Africa they may join the Sudan golden sparrow (Passer luteus) and various estrildids.

[7] The red-billed quelea needs 300–800 mm (12–31 in) of precipitation to breed, with nest building usually commencing four to nine weeks after the onset of the rains.

[7][25]: 5, 12  Nests are usually built in stands of thorny trees such as umbrella thorn acacia (Vachellia tortilis), blackthorn (Senegalia mellifera) and sicklebush (Dichrostachys cinerea), but sometimes in sugar cane fields or reeds.

[26] The male starts the nest by creating a ring of grass by twining strips around both branches of a hanging forked twig, and from there bridging the gaps in the circle his beak can reach, having one foot on each of the branchlets, using the same footholds and the same orientation throughout the building process.

[7] Flocks of red-billed queleas usually feed on the ground, with birds in the rear constantly leap-frogging those in the front to exploit the next strip of fallen seeds.

[7] Red-billed queleas feed mainly on grass seeds, which includes a large number of annual species from the genera Echinochloa, Panicum, Setaria, Sorghum, Tetrapogon and Urochloa.

[31] When the supply of these seeds runs out, seeds of cereals such as barley (Hordeum disticum), teff (Eragrostis tef), sorghum (Sorghum bicolor), manna (Setaria italica), millet (Panicum miliaceum), rice (Oryza sativa), wheat (Triticum), oats (Avena aestiva), as well as buckwheat (Phagopyrum esculentum) and sunflower (Helianthus annuus) are eaten on a large scale.

Red-billed queleas have also been observed feeding on crushed corn from cattle feedlots, but entire maize kernels are too big for them to swallow.

[24] As much as half of the diet of nestlings consists of insects, such as grasshoppers, ants, beetles, bugs, caterpillars, flies and termites, as well as snails and spiders.

[25]: 11 Natural enemies of the red-billed quelea include other birds, snakes, warthogs, squirrels, galagos, monkeys, mongooses, genets, civets, foxes, jackals, hyaenas, cats, lions and leopards.

Nile crocodiles sometimes attack drinking queleas, and an individual in Ethiopia hit birds out of the vegetation on the bank into the water with its tail, subsequently eating them.

[35] Woven traps made from star grass (Cynodon nlemfuensis) are used to catch hundreds of these birds daily in the Kondoa District, Tanzania.

[36] The governments of Botswana, Ethiopia, Kenya, South Africa, Sudan, Tanzania, and Zimbabwe have regularly made attempts to lessen quelea populations.

The most common method to kill members of problematic flocks was by spraying the organophosphate avicide fenthion from the air on breeding colonies and roosts.