Environmental influences on variation in nest-characteristics in a long-term study population of the Superb Lyrebird, Menura novaehollandiae

Abstract

Nests provide essential ecological services to breeding birds, and the location and architectural characteristics of nests may vary to maximise reproductive success. We investigated variation in nest-characteristics within a breeding population of Superb Lyrebirds (Menura novaehollandiae) in south-eastern Australia over 14 years. Lyrebird nests consist of a bulky, domed chamber built on a supporting platform of sticks. A total of 292 nests successful to the nestling stage was measured. The orientation of nests differed from random, with nests predominantly facing downslope, and the volume of the internal chamber (a surrogate of the size of nests) was smaller in high nests (≥2 m above ground). Mean width of the nest-wall (per year) and median height above ground (per year) were positively correlated with rainfall during the nest-building period (March—June) but not with temperature, suggesting that water resistance rather than thermal insulation is a stronger influence on nest traits. Variation in nest-characteristics between individuals was identified, indicating particular styles of nest in the population. For the Superb Lyrebird, flexibility in location and architecture of the nest, within and between years, is likely to represent a mechanism to respond to variation in environmental conditions and predation risk, which may affect reproductive success.