Quantifying the future value of cacheable food using fox squirrels (sciurus niger)
In: Israel Journal of Ecology and EvolutionBiology Department, Dixie State University of Utah
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Food caching allows foraging decisions to include both present and future food value. We developed and tested a conceptual framework for measuring animals’ perceptions of future vs. present food value. Fox squirrels (Sciurus niger) are well-known caching animals in North America. We measured giving-up densities (GUDs) of fox squirrels to test the following hypotheses: (1) all else equal, animals should prefer cacheable to non-cacheable foods, and (2) the option value of a cacheable food should change seasonally and be highest preceding lean periods. We presented squirrels with experimental food patches containing either shelled hazelnuts, hazelnuts with their shells intact (to affect cacheability) or both kinds. Our data support both hypotheses. Squirrels exploited food patches with cacheable nuts more thoroughly and left them at lower GUDs. The squirrels’ perception of the future value of hazelnuts with their shells intact was found to be 32% higher than their present value. GUDs also varied by season, fall > spring >winter > summer, likely corresponding to food availability. Season and food cacheability interacted to further determine GUDs. The difference in GUDs between cacheable and non-cacheable nuts varied similarly: fall > spring > winter > summer, likely corresponding to changing food availability, reproductive opportunities and pending energetic shortfalls.
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Quantifying the future value of cacheable food using fox squirrels (sciurus niger)
In: Israel Journal of Ecology and EvolutionBiology Department, Dixie State University of Utah
Search for other papers by Marius van der Merwe in
Current site
Google Scholar
PubMed
Search for other papers by Joel S. Brown in
Current site
Google Scholar
PubMed
Search for other papers by Burt P. Kotler in
Current site
Google Scholar
PubMed
Food caching allows foraging decisions to include both present and future food value. We developed and tested a conceptual framework for measuring animals’ perceptions of future vs. present food value. Fox squirrels (Sciurus niger) are well-known caching animals in North America. We measured giving-up densities (GUDs) of fox squirrels to test the following hypotheses: (1) all else equal, animals should prefer cacheable to non-cacheable foods, and (2) the option value of a cacheable food should change seasonally and be highest preceding lean periods. We presented squirrels with experimental food patches containing either shelled hazelnuts, hazelnuts with their shells intact (to affect cacheability) or both kinds. Our data support both hypotheses. Squirrels exploited food patches with cacheable nuts more thoroughly and left them at lower GUDs. The squirrels’ perception of the future value of hazelnuts with their shells intact was found to be 32% higher than their present value. GUDs also varied by season, fall > spring >winter > summer, likely corresponding to food availability. Season and food cacheability interacted to further determine GUDs. The difference in GUDs between cacheable and non-cacheable nuts varied similarly: fall > spring > winter > summer, likely corresponding to changing food availability, reproductive opportunities and pending energetic shortfalls.
| All Time | Past 365 days | Past 30 Days | |
|---|---|---|---|
| Abstract Views | 846 | 84 | 15 |
| Full Text Views | 30 | 0 | 0 |
| PDF Views & Downloads | 39 | 0 | 0 |
