Agonistic carotenoid signalling in male red-collared widowbirds: aggression related to the colour signal of both the territory owner and model intruder.
Multiple receivers, multiple ornaments, and a trade-off between agonistic and epigamic signaling in a widowbird. Am.
The Spectacled Weaver is a species of Southern African bird in the Ploceidae family which includes birds such as Weavers, Queleas, Widowbirds
. It is found widely in woodland, forest edge and gardens of East, Middle and Southern Africa, but is absent from the most arid regions (such as the Karoo) and dense, primary rainforest.
Female preference for long tails in lekking Jackson's widowbirds
: experimental evidence.
Visual Traits Female preferences for long tails in long-tailed widowbirds
Additional chapters include descriptions of bustards (arid-adapted Old World species); kakapos (a New Zealand nocturnal parrot), hummingbirds, and lyrebirds (Australian mimics); and African long-tailed whydahs and widowbirds
. The author's broad definition of arena behavior justifies his inclusion of two chapters concerning ducks and bower birds.
On the other hand, the same trait may be favored by different types of sexual selection in different species; for instance, in one species of widowbirds
(Euplectes progne), the long tails of males influence female choice but not the outcome of contests between males (Andersson 1982), whereas the converse is true in a congener (E.
Sexual dimorphism and modes of sexual selection in lekking Jackson's widowbirds
Euplectes jacksoni (Ploceinae).
with experimentally exaggerated tails had higher reproductive success (Andersson 1982).
Examples of this approach involve adjusting clutch size (references above), tail length in widowbirds
(Andersson 1982), or offspring size by yolk removal from eggs (Sinervo and McEdward 1988; Sinervo 1990; Sinervo and Huey 1990).
Most recently, across 14 species of widowbirds
and bishops (genus Euplectes), Andersson and Andersson (1994) have demonstrated that sexual dimorphism in wing length is independently related not only to dimorphism in body size but also to sexual dimorphism in tail length and to the incidence of display flights.
Male tail length among the 16 species of widowbirds
and bishops (genus Euplectes) varies considerably, from 3 to 50 cm (females are cryptically colored and have short tails), and recent evidence from three of these is consistent with the hypothesis that their long tails are adaptations arising from sexual selection (M.