Landscape modulation by a mound-building bird; creating novel, high-resource patches in a semi-arid woodland

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Heather Neilly and Peter Cale, Australian Landscape Trust, Renmark, SA, Australia, Heather Neilly, Ecology and Environmental Science, University of Adelaide, Adelaide, SA, Australia, Heather Neilly, Ecology and Environment and Evolution, La Trobe University, Melbourne, VIC, Australia, David J. Eldridge, Evolution and Ecology Research Centre, School of Biological, Earth, and Environmental Sciences, University of New South Wales, Sydney, NSW 2052, Australia

Background/Question/Methods
Desert ecosystems have sparse and heterogeneous resources. Discrete high-resource patches, associated with landscape modulators such as perennial vegetation, act as nutrient sinks in contrast to open, low-resource areas (interpatch matrix). In semi-arid mallee woodlands, malleefowl (Leipoa ocellata: Megapodiidae) create large incubation mounds by raking leaf litter and soil from high-resource patches to their mound sites in the interpatch matrix. Despite this conspicuous redistribution of resources, nothing is known about the physical and chemical properties of malleefowl mounds. In this study, we measured groundcover, vegetation structure and composition, and soil chemistry at: malleefowl mounds, high-resource microsites modulated by trees, and in the low-resource interpatch matrix. The high and low-resource microsites were sampled near the mound in the potential Malleefowl disturbance zone, and outside of the disturbance zone. Mounds were classified into three age categories based on the number of years since they were active.
Results/Conclusions
We found that malleefowl mounds were a novel microsite, with soil chemistry more similar to tree-modulated patches and groundcover and vegetation variables more similar to the open, interpatch matrix. Additionally, the novel attributes of the mound persisted beyond 6 years from the last time the mound was active. The effect of malleefowl mound-building activities appeared to extend beyond recently used mounds, with lower plant richness in open patches close to the mound. Malleefowl redistribute resources from high-resource patches under trees to the open interpatch matrix. Incubation mound-building by animals can be a landscape modulating process via high-resource patch formation, and is likely important for ecosystem functioning.