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Keywords:

  • Araucaria Forest;
  • caching;
  • distance dispersal;
  • rodent;
  • seed dispersal;
  • seed predation

Abstract

We studied the seed predation and scatter-hoarding behaviour of Azara's agoutis Dasyprocta azarae (Rodentia: Dasyproctidae) in relation to the seeds of the Brazilian ‘pine’, Araucaria angustifolia (Araucariaceae), the rodent's main winter food source. We compared seed-removal rates, seed-caching rates, cache distances and recovery rates between a summer period of food abundance (with a low demand for A. angustifolia seeds and no such seeds naturally available) and a winter period of food scarcity (with a high demand for A. angustifolia seeds). We investigated whether the relative seed value affected the rodent's seed-handling behaviour. We predicted that during the high seed-demand period (winter): (1) cache distances would be greater; (2) fewer seeds would be stored; (3) more seeds would be recovered and the seed-recovery time would be lower. In support of our first two predictions, the caching distances were greater in winter (mean ± SE = 15.67 ± 5.11 m) than in summer (9.40 ± 1.59 m), and agoutis hoarded >9 times more seeds in summer (55) than in winter (6). Our third prediction was not supported, and the proportion of unrecovered caches and buried seed recovery times did not differ between winter (mean ± SE = 3.00 ± 0.00 days, n = 5 seeds) and summer (11.05 ± 3.68 days, n = 20 seeds). The high resource density (during summer) rather than the density of A. angustifolia seeds likely influenced seed fate. Agoutis acted mainly as predators, leaving few intact seeds, caching a low proportion of handled seeds (≅ 8%) and rapidly consuming the caches. Agoutis may cache seeds to keep them safe from competitors on a short-term basis rather than maintaining medium- or long-term reserves for use during food-scarcity periods.