Oral presentation- Open Session 12th International Mammalogical Congress

Ecosystem modifiers create cache sites with microclimate that reduces seed release (#167)

John L Koprowski 1
  1. University of Arizona, Tucson, Arizona, United States of America

The evolution of seed caching is influenced by availability and perishability, which are related to climate.  Future value is a major determinant of caching strategy and is likely influenced by perishability.  Animals should select sites that reduce pilferage, promote relocation, and retard seed degradation.  Across coniferous forests of North America, red squirrels (Tamiasciurus hudsonicus) are ecosystem modifiers that maintain iconic larderhoards within conspicuous piles of cone scales known as middens. We test the hypothesis that middens function as cool, moist sites that promote cone storage, deter seed germination and reduce seed dispersal.  We assessed external and internal microclimates and forest structure, and detailed consequences of midden microclimates to cone opening.  Our results delineate the adaptive nature of larderhoarding in middens.  Midden internal microclimate is related to surface conditions, which are influenced by forest characteristics.  Cone opening increased with temperature and decreased with moisture.  Middens serve as cool, moist locations that retard perishability and facilitate cone storage.  Small differences in temperature have important impacts on cone opening and efficacy of cone storage.  Furthermore, global change is predicted to result in microclimates that may not be conducive to cone storage and suggest the broader vulnerability of animal caches to climate change.