Birds
Red-billed Quelea
Quelea quelea · also called red-billed weaver, feathered locust
There is no wild bird on Earth more numerous than the red-billed quelea. A small brown African weaver, it moves across the savanna in flocks of millions, breeds in colonies of tens of millions, and arrives at a ripening grain field like a plague of locusts.
Overview
Quelea quelea lives in the semi-arid grasslands and farmland of sub-Saharan Africa, from the Sahel to South Africa, following the seasonal rains. It eats almost entirely grass seed, switching to cultivated cereals when wild seed runs short. Its breeding population is estimated at about 1.5 billion adults, the most of any wild bird.
Flocks and colonies
Outside breeding, queleas form flocks of millions that wheel like smoke and roost in numbers that snap branches. When rain brings a flush of seed, they breed in colonies of tens of millions of nests, and the whole cycle of building, laying, and fledging takes about six weeks before the birds move on.
Africa’s worst bird pest
A flock can strip a smallholder’s grain crop in a day. Governments spray roosts and colonies from the air, killing millions at a time, but it barely touches the population.
Status
Least Concern — hugely abundant, stable, and effectively impossible to reduce.
Red-billed Quelea: common questions
Is the red-billed quelea really the most common bird in the world?
Among wild birds, yes, by the usual estimates. Its breeding population is put at around one and a half billion adults, and after each breeding season, before the natural die-off, the total may be several times higher. No other wild bird comes close on a global scale; the next contenders, such as some other African weavers, various finches, and the domestic-descended feral pigeon, are an order of magnitude fewer. If domesticated birds are included, the chicken, at roughly 25 to 35 billion, is more numerous, but the quelea holds the record for a wild species.
Why is it called the feathered locust?
Because it behaves, from a farmer's point of view, exactly like a locust swarm. A quelea flock can number in the millions, it descends on a field of ripening millet or sorghum in a rolling wave, with birds at the back constantly leapfrogging to the front, and it can strip the grain from a small farm's entire crop in a matter of hours. Like locusts, the flocks are highly mobile, appearing suddenly, moving on unpredictably with the rains, and being almost impossible to keep out of a field. The comparison is old and widespread across the quelea's range.
Why does killing millions of them not reduce the population?
Because the losses are trivial against the total and the birds breed back so fast. Control operations that spray a roost or blow up a colony may kill one to several million queleas in a single night, and campaigns across a country might account for tens of millions in a year. But with a wild population of well over a billion, a rapid breeding cycle that can be repeated several times as birds chase the rains, and enormous natural mortality already built into the life history, those removals are absorbed within a season. Many scientists now argue that large-scale killing is expensive, ecologically damaging, and pointless as population control, and that farmers are better served by scaring devices, early-maturing crop varieties, and targeted local action.
How do queleas cause so much damage if they mainly eat wild grass seed?
Wild annual grasses are their staple, and in a normal year the vast flocks feed on the seed of the natural grassland. The problem comes at the times and places where the wild seed supply fails or is exhausted, often late in the dry season, and a huge flock arrives in a farming district just as the cultivated cereal is in the milky, ripening stage. Cultivated millet, sorghum, and wheat are simply concentrated, reliable patches of exactly the kind of grass seed the quelea is built to eat, so the flock switches to the crop, and the concentration of both birds and food in one field is what produces the catastrophic local losses.