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Behavioural flexibility of the platypus (Ornithorhynchus anatinus) in response to changing water depth in a drought-affected Tasmanian stream

Simon Roberts, Melody Serena

Abstract

Context. Many Australian freshwater species are well adapted to survive dry periods. However, the effect of drought on platypus behaviour has not previously been studied. Aims. We investigated how the temporal and spatial distribution of platypus foraging activity varied during a cease-to-flow event lasting nearly 2 months along a normally perennial Tasmanian stream. Methods. The frequency and duration of platypus activity in run, riffle and pool habitats was monitored using time-lapse cameras. Key results. Total wetted area within the study area dropped to ⁓40% of its normal extent by the end of the cease-to-flow period. In response, platypus activity became more nocturnal and was increasingly concentrated in the best remaining aquatic habitat (pools); the mean duration of a foraging bout in a given pool during cease-to-flow was ⁓7 times greater than the corresponding interval when discharge was high. The likelihood of diurnal activity on any given day was significantly related to creek depth but not maximum daily air temperature. Conclusions. The observed changes in platypus behaviour plausibly represent strategies to maximise foraging success and limit predation risk. Implications. The platypus’s ability to survive extended cease-to-flow periods relies on its having access to sufficiently large and productive refuge habitats.

MF25030  Accepted 10 April 2025

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