Weaver news

Paper: Raptors breeding on weaver nests in trees and on man-made structures

2019-03-29 (835)

White-backed Vulture nest on top of Sociable
Weaver nest in tree; Photo: Neil Thomson
Raptors are known to breed on top of weavers nests but are they willing to follow the weavers onto man-made structures?

Paper: Oschadleus HD. 2019. Raptors breeding on weaver nests in trees and on man-made structures. Ostrich 90(1):85-88.

Abstract. Several raptor species nest on top of large weaver nests. These weaver nests are usually sited in trees, but 11.7% of Red-billed Buffalo-Weaver Bubalornis niger and 25.7% of Sociable Weaver Philetairus socius nests occur on man-made structures. In an extensive literature search, a total of 16 raptor species were recorded as nesting on top of weaver nests. At least 10 raptor species used weaver nests built in trees. Seven raptor species used weaver nests on man-made sites and four raptor species only used weaver nests built on man-made sites. No owls have been recorded as using weaver nests on man-made sites. There are historical records of raptors nesting on top of weaver nests in trees, while nesting on top of weaver nests sited on man-made structures appears to be a more recent adaptation. Costs and benefits of nesting on man-made sites are briefly listed. Nesting on man-made sites may increase (by both weavers and raptors) and raptor researchers are encouraged to document cases of raptors nesting on weaver nests where these are placed in trees or artificial sites, so that there is a record of changes in frequency of nest site usage by raptors.

Verreaux's Eagle nest on top of Sociable Weaver nest
on man-made site; Photo: Japie Claassen

Raptor species listed in the paper:

Secretarybird Sagittarius serpentarius
White-backed Vulture Gyps africanus
Lappet-faced Vulture Torgos tracheliotos
Brown Snake Eagle Circaetus cinereus
Bateleur Terathopius ecaudatus
Martial Eagle Polemaetus bellicosus
Tawny Eagle Aquila rapax
Verreauxs' Eagle Aquila verreauxii
Pale Chanting Goshawk Melierax canorus
Jackal Buzzard Buteo rufofuscus
Barn Owl Tyto alba
White-faced Owl Otus leucotis
Spotted Eagle Owl Bubo africanus
Giant Eagle Owl Bubo lacteus
Rock Kestrel Falco tinnunculus
Greater Kestrel Falco rupicoloides