Probably the red billed quelea finch (Quelea Quelea) which has a known population of 2-3 billion birds.

The English meaning for the Kikuyu word thuriu is Quelea quelea.

Q. quelea, or Red billed quelea are one species of the African weaverbird. Traveling in huge flocks, in years when rainfall is good and cereal crops do well, they are voracious crop pests, descending on fields in flocks of millions, the birds decimate entire crops.

Joyce I. Magor has written:

'Illustrated descriptions, distribution maps and bibliography of the species of Quelea (weaver-birds, Ploceidae)' -- subject(s): Quelea

Quelea is a small bird that belongs to the weaver family Ploceidae. They exist only in Africa. They are similar to a sparrow or finch, with bills adapted to eating seeds.