How energy and coavailable foods affect forage selection by the western grey kangaroo

Publication Type:
Journal Article
Year of Publication:
Michael H. Parsons, Byron B. Lamont, Stephen J. J. F. Davies, Benjamin R. Kovacs
Animal Behaviour
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We aimed to identify chemical properties of plant species that correlate with their palatability, quantify a common currency of forage for the western grey kangaroo, Macropus fuliginosus, and test the impact of frequency of occurrence on food selection. Of 24 plant species exposed to kangaroos, those high in salts and tannins were avoided, whereas those high in acid-digestible fibre were often favoured; protein content was not related to palatability. We then performed cafeteria tests with two captive and semiwild populations. Food pellets contained additional fructose, NaCl, citric acid or tannins. We also used energy-enhanced and balanced control pellets. Despite wide geographical separation, the kangaroo populations expressed the same eating patterns. High-energy pellets were preferred. When these were removed, fructose (an indicator of energy) assumed the most preferred rank. Our study affirms the tendency of herbivores to select flavours associated with high energy, suggesting that energy is important in determining a currency of forage for the western grey kangaroo. The [`]deterrent substances’, tannins and NaCl, were more likely to be eaten when rare. The high selection of the control diet, which was fed ad libitum throughout the study, may provide additional evidence that frequency of occurrence affects selectivity, favouring the common element when palatable, and the rare element when not palatable.


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