Seasonal patterns of abundance of insectivorous birds and flying insects

Abstract

Insectivorous birds made up only 8% of all birds in heathland near Sydney and only 18% in open forest; other birds were almost all honeyeaters. The abundance of Variegated Wrens, the most commonly recorded insectivore, showed no consistent seasonal pattern in the heathland. Otherwise the abundances of insectivorous birds were lowest during June to August and peaked during September to November or December to February. Average biomass of flying insects exhibited peaks during September to December and March to April and troughs at other times, especially during May to August. Except for the period September to November, when insectivore density and biomass of flying insects were both at their highest levels, the correspondence between the two was poor.