The southern cassowary (Casuarius casuarius johnsonii) remains an important disperser of native plants in fragmented rainforest landscapes

Mariana A. Campbell, Tom Lawton, Vinay Udyawer, Kim S. Bell-Anderson, David Westcott, Hamish A. Campbell

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Abstract

Large-bodied frugivores are essential to the ecological function of rainforest communities. The southern cassowary (Casaurius casuarius johnsonii) is the only large frugivore in the tropical rainforests of Australia. Here, we assessed whether cassowaries remain important to native plant seed dispersal in areas where the rainforest is highly fragmented, and exotic fruits are abundant. To do this, we developed a tri-axial acceleration logger integrated with a motion sensor and VHF radio transmitter. The telemetry device was small enough to be hidden inside a native fruit. The cassowaries ingested it, transported it and defecated it up to 24 h later with the seeds from the fruits they had ingested during the tracking period. The telemetry device was then located by VHF radio and collected with the scat. The distance travelled, activity profile, consumed fruit diversity, and scat energy content were assessed for cassowaries inhabiting regions with different degrees of urbanization. We found that cassowaries inhabiting more urbanized areas consumed the greatest proportion of fruits from exotic plants (~30%) but still incorporated a significant proportion of fruits from native plants in their diet. These individuals existed in higher states of activity and rested less than individuals inhabiting more intact swathes of rainforest, actively moving between urban gardens and the rainforest. The study shows cassowaries have a flexible foraging strategy that has enabled them to persist in rainforest-fragmented landscapes. They remain a significant disperser of seeds from native plants between rainforest patches, and as such, cassowaries remain essential in maintaining native plant diversity within these fragmented patches.

Original languageEnglish
Pages (from-to)787-802
Number of pages16
JournalAustral Ecology
Volume48
Issue number4
Early online date21 Mar 2023
DOIs
Publication statusPublished - Jun 2023

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