How do complex economies evolve? We study the adaptive value of economic decisions in scatter hoarding rodents, animals that create wealth by ‘banking’ seeds for periods of scarcity, such as winter (squirrels) or drought (kangaroo rats). Scatter hoarders can tell us about brain function [HIPPOCAMPAL MAPS] but we currently focus on behavior, including their development [SQUIRREL SCHOOL]. Scatter hoarders put ‘one egg in each basket’, necessitating three decision phases: assess and invest (measure and allocate cache effort to the item), manage the cache field (optimizing distribution to decrease cache raiding) and retrieval (and raiding) decisions. We have studied these phases in captive and free-ranging scatter hoarders and found that squirrels show a remarkable degree of heuristic precision during the assessment and investment stage, even organizing their caches in a way that may enhance later recall of their locations.
Delgado, M.M. and Jacobs, L.F. (2017) Caching for what and where: evidence for a mnemonic strategy in a scatter-hoarder. Royal Society Open Science. 4: 170958. http://dx.doi.org/10.1098/rsos.170958
Delgado, M.M. and Jacobs, L.F. (2016). Inaccessibility of reinforcement increases persistence and signaling behavior in the fox squirrel, Sciurus niger. Journal of Comparative Psychology. 130(2): 128-137.
Delgado, M. M. , Nicholas, M. , Petrie, D. J., & Jacobs, L. F. (2014). Fox squirrels match food assessment and cache effort to value and scarcity. PLoS ONE, 9(3), e92892. doi:10.1371/journal.pone.0092892.s003
Waisman, A.S. , Lucas, C.G., Griffiths, T., and Jacobs, L.F. (2011). A Bayesian model of navigation in squirrels. Proceedings of the 33rd Annual Conference of the Cognitive Science Society.
Preston, S.D. , and Jacobs, L.F. (2009). Mechanisms of cache decision making in fox squirrels (Sciurus niger). Journal of Mammalogy 90, 787-795.
Waisman, A.S. , and Jacobs, L.F. (2008). Flexibility of cue use in the fox squirrel (Sciurus niger). Animal Cognition 11, 625-636.
Gibbs, S.E.B. , Lea, S.E.A., and Jacobs, L.F. (2007). Flexible use of spatial cues in the southern flying squirrel (Glaucomys volans). Animal Cognition 10, 203-209.
Barkley, C.L. , and Jacobs, L.F. (2007). Sex and species differences in spatial memory in food-storing kangaroo rats. Animal Behaviour 73, 321-329.
Preston, S.D. , and Jacobs, L.F. (2005). Cache decision making: the effects of competition on cache decisions in Merriam’s kangaroo rat (Dipodomys merriami). Journal of Comparative Psychology 119, 187-196.
Preston, S.D., and Jacobs, L.F. (2001). Conspecific pilferage but not presence affects Merriam’s kangaroo rat cache strategy. Behavioral Ecology 12, 517-523.
Lavenex, P. , Steele, M.A., and Jacobs, L.F. (2000). The seasonal pattern of cell proliferation and neuron number in the dentate gyrus of wild adult eastern grey squirrels. European Journal of Neuroscience 12, 643-648.
Barkley, C.L. , and Jacobs, L.F. (1998). Visual environment and delay affect cache retrieval accuracy in a food-storing rodent. Animal Learning & Behavior 26, 439-447.
Lavenex, P. , Shiflett, M. , Lee, R. , & Jacobs, L. F. (1998). Spatial versus nonspatial relational learning in free-ranging fox squirrels (Sciurus niger). Journal of Comparative Psychology, 112(2), 127-136.
Jacobs, L.F., and Shiflett, M.W. (1999). Spatial orientation on a vertical maze in free-ranging fox squirrels (Sciurus niger). Journal of Comparative Psychology 113, 116-127.
Lavenex, P., Steele, M.A., and Jacobs, L.F. (2000). Sex differences, but no seasonal variations in the hippocampus of food-caching squirrels: A stereological study. Journal of Comparative Neurology 425, 152-166.
Jacobs, L.F. (1996). The economy of winter: Phenotypic plasticity in behavior and brain structure. Biological Bulletin 191, 92-100.
Jacobs, L.F., and Spencer, W.D. (1994). Natural space-use patterns and hippocampal size in kangaroo rats. Brain Behavior and Evolution 44, 125-132.
Sherry, D.F., Jacobs, L.F., and Gaulin, S.J.C. (1992). Adaptive specialization of the hippocampus. Trends in Neurosciences 15, 298-303.
Jacobs, L.F. (1992). The effect of handling time on the decision to cache by grey squirrels. Animal Behaviour 43, 522-524.
Daly, M., Jacobs, L.F., and Wilson, M.I. (1992). Scatter-hoarding by kangaroo rats (Dipodomys merriami) and pilferage from their caches. Behavioral Ecology 3, 102-111.
Daly, M., Behrends, P., Wilson, M., & Jacobs, L. F. (1992). Behavioural modulation of predation risk: moonlight avoidance and crepuscular compensation in a nocturnal desert rodent, Dipodomys merriami. Animal Behaviour, 44(1), 1–9.
Jacobs, L. F. (1992). Memory for cache locations in Merriam’s kangaroo rats. Animal Behaviour, 43(4), 585–593.
Jacobs, L.F., and Liman, E.R. (1991). Grey squirrels remember the locations of buried nuts. Animal Behaviour 41, 103-110.