Non-breeding territoriality in the New Holland Honeyeater, Phylidonyris novaehollandiae, in an unpredictable environment—short-term energy costs for possible long-term reproductive benefits

Abstract

The short-term energetic and long-term reproductive costs and benefits of aggressive social behaviour of New Holland Honeyeaters were examined in an open forest where nectar availability for part of the year was highly unpredictable. Despite the variability in food supply, birds consistently maintained priority and, to varying degrees, exclusive access to certain areas. Feeding territories held between the autumn and spring breeding seasons did not always provide sufficient energy to cover the owner's daily costs of occupation. An indirect assessment of the net energy benefits revealed that owners may experience considerable periods of food shortage. Despite this, owners remained site faithful as the areas defended were all close to, or overlapped, sites used for nesting. These areas had a high density of both Banksia spp. (food plants) and Leptospermum spp. (nest plants). It appears that while non-breeding territories may be unprofitable in the short term, owners that maintain them benefit in the long term by ensuring access to nesting sites.