Nest height of the red bishop (<i>Eupiectes orix</i>)

Abstract

Heights of nests and reeds in a colony of red bishops (Euplectes orix) in Phragmites mauritianus reeds on the Makabusi River, Zimbabwe were measured in two breeding seasons. Nests were placed high in the reeds with fewer above the mean and more below the mean than in a normal distribution. During the course of a breeding season, nest height increased in response to increasing reed height and the nest height/reed height percentage was relatively constant at 70%. Nest height had a higher correlation and regression coefficient with reed height in lower reeds than in reeds over 280 cm tall. Most nests were placed in reeds with diameters of 10-12 mm. Higher positions, where the diameters of the reeds were smaller than this, the reeds were weaker probably because of a lack of llgnificatlon. In one breeding season, nests used by females were significantly lower than nest frames left unused but breeding success appeared unaffected by variation in nest height. Nesting high in the reeds might be a response to ground predators and climatic factors, particularly the requirement for nest ventilation to remove excess water vapour.