Selection of nest platforms and the differential use of nest building fibres by the Baya weaver, Ploceus philippinus Linnaeus 1766

Abstract

The choice by the Baya weaver between different plant species as nesting platforms and sources of nesting fibre was analysed on an agricultural study plot at Chorao (15 degrees 30'N, 73 degrees 50'E), an island in the Mandovi estuary in Goa, India. The bird chose eucalyptus over coconut palms, as shown by a higher ratio of utilised trees to available trees and by the maintenance of significantly higher numbers of total nests (t = 2.92, P less than 0.05) and viable nests (t = 3.10, P less than 0.05). The wider anchoring area, providing a better display front for the male birds competing for mates, and the protection against monsoon vagaries (such as rains and winds) provided by the extensive drooping canopy of profuse branches seem to have favoured of eucalyptus trees over coconut palms.The choice went against short and medium sized coconut palms and tall eucalyptus trees, as probably the former were more prone to the menace of intruders and the latter were more exposed to strong monsoon winds.The birds exhibited a differential use of nesting fibres to fabricate the different zones of the nest.Sugarcane fibres, which probably provided better anchorage and stability due to their interlocking silicious spicules, were used for the base, stalk and roof of the brood chamber. Fibres from coconut leaves went into the construction of the entrance tube and floor of the brood chamber, probably to provide added comfort to the altricial young and incubating parent and to afford the required resistance against wear and tear owing to frequent movements of the mother bird while ferrying food to the young.