Feeding Behaviour of the Platypus and the Azure Kingfisher in Sub-Tropical Australian Streams

Megan Boelter and Jeff McKee

Observations on platypus and azure kingfishers from southern and central Queensland confirmed that azure kingfishers often prey on invertebrates that are disturbed by feeding platypus. The kingfishers deliberately track platypus feeding along the stream bed and wait for an opportunity to dive for small crustaceans and fish that are flushed by the platypus activity.  The interaction obviously benefits the kingfisher who can save time and energy on foraging; at this stage of the investigation we have observed no obvious reciprocal benefit to platypus. Despite the fact that both species occur together on streams along the east coast, this behaviour is only seen from central Queensland and further north.  The evolution of this interaction implies strong diurnal activity in sub-tropical platypus while temperate and sub-alpine platypus are reported as nocturnal. One hypothesis is that tropical streams have higher platypus carrying capacity as water temperatures and invertebrate productivity are higher and more stable throughout the year.  Social interactions and spatial requirements may then dictate temporal habitat sharing in tropical streams, restricting a subset of the population to diurnal feeding time slots. Platypus-kingfisher commensal behaviour may well be a good indicator of habitat integrity as it has been predominantly observed in undisturbed riparian zones and a consistently clear water column is prerequisite.