Aspects of the biology of the red bishop Euplectes orix and other Euplectes species.
Loading...
Date
1977
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
Abstract
The breeding biology and the annual cycle of the Red
Bishop Euplectes orix was studied over a two year period
in Natal. Some comparative data were also gathered for
the related species the Red-shouldered Widow E. axillaris
and the Red-collared Widow E. ardens, and additional data
from a ringer in Rhodesia have been analysed. The breeding
season of these polygynous ploceids coincides with the
summer rainy season, and the amount of breeding activity
in the Red Bishop appeared to be correlated with the
amount of rain during the previous year. Breeding success
at the colony studied was low; predation was the major
cause of nest failure. In all three species the entire
population, including the juveniles, undergoes a complete
moult at the end of the breeding season. There is some
evidence that the birds may make local movements during
the winter dry season.
These species are sexually dimorphic, the males being
larger than the females. The population sex ratio was
Significantly biased in favour of males in the Red Bishop
and the Red-shouldered Widow but not in the Red-collared
Widow. However, about half the male birds are subadults
which do not breed, so that there is an excess of females
in the breeding population. Adult males undergo a partial
moult at the start of the breeding season and acquire a
distinctive nuptial plumage. This is shed again at the
post-nuptial moult, and in eclipse plumage they resemble
the females. There is a similar pattern of weight change
in all three species, with peaks early in the breeding
season and again during the moult. The lowest annual
weights are recorded during the dry season. The mortality
rate of the Red Bishop is not high for a small passerine.
The findings of this study are compared with the
available information on other members of the genus, and
discussed in relation to the evolution of polygyny in the
Euplectes species.
Description
Thesis (Ph.D.)-University of Natal, Pietermaritzburg, 1977.
Keywords
Birds--KwaZulu-Natal., Theses--Zoology.