Pulses Resources and the Pace-Of-Life Syndrome in Eastern Chipmunks

Denis REALE
Département des sciences biologiques, Université du Québec à Montréal, Canada reale.denis@uqam.ca   

(Seminar in English)

Animal populations have to deal with temporal and spatial availability of resources. Pulsed resources represent an extreme case of resources fluctuation in a way that they are produced in huge amounts during restricted periods and are almost inexistent the rest of the time. Such pulsed resources create a challenge to animals exploiting them, as these consumers have to find ways to adjust their life history in response to these fluctuations. This is the case of the eastern chipmunk (Tamia striatus) a small Sciurid commonly found in North-American forests, and that relies mainly on the American beech (Fagus grandifolia) in the northern regions of its distribution range. Once every 2-3 years, beech trees produce massive amounts of seeds, during what is generally called a masting event. Although eastern chipmunks can feed on different plants, small invertebrates, and other sources of food, they rely mostly on beech seeds for their reproduction and winter survival. Chipmunks store seeds into their burrow over the summer and the fall, and use these resources for their winter needs.

Here we show the case of a chipmunk population in Southern Quebec that we have followed for 10 years. In this individually marked population, we have collected information on individual burrow locations, habitat characteristics, behaviour, physiology, and genetics. Using this long-term data set we show how chipmunks life history and ecology depends strongly on beech seed fluctuations. Chipmunk reproductive cycles and population demography depend on masts; chipmunks do not reproduce every year, but concentrate their reproductive effort around masting events. Masts affect winter torpor, dispersal and the genetic structure of the population. Furthermore, because of the temporal fluctuation of seed production, chipmunks born at different cohorts show different life history strategies and personalities, and our results show cohort-dependent personality types fitted with specific life histories. Our results shed light on how fluctuation in ecological conditions may maintain personality differences and on the nature of the relationships between animal personality and life history.

Recent publications:

Montiglio P.O., Garant D., Dubuc Messier G., Bergeron P., & D. Réale. 2014. Pulsed resources and the coupling between life-history strategies and exploration patterns in eastern chipmunks (Tamias striatus). Journal of Animal Ecology. 83, 720-728.

Bergeron, P., Réale, D., Humphries, M. M. & D. Garant. 2011. Anticipation and response to fluctuating pulsed resources drive population dynamics in eastern chipmunks. Ecology 92, 2027-2034.

Réale, D., Garant D., Humphries M., Careau V., Bergeron, P. & Montiglio P.O. 2010. Personality and the emergence of a pace-of-life syndrome at the level of the population. Philosophical Transactions of the Royal Society of London B 365, 4051-4063.