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Does Reproductive Synchrony Affect Juvenile Survival Rates of Northern Mammals?
Mark O'Donoghue and Stan Boutin
Vol. 74, No. 1 (Oct., 1995), pp. 115-121
Stable URL: http://www.jstor.org/stable/3545680
Page Count: 7
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Predator swamping is often cited as an adaptive function of reproductive synchrony. We measured juvenile survival rates of two boreal mammals, snowshoe hares (Lepus americanus) and red squirrels (Tamiasciurus hudsonicus), and evaluated the effect of timing of birth relative to the population mean on subsequent survival. Reproduction of hares was highly synchronous. Juvenile hares were born in three distinct litter groups per summer, and they suffered high early mortality due to predation. Juveniles born closest to the population mean had higher survival than those born later for two of the three litter groups. The timing of red squirrel litters was more variable, and squirrels only had one litter per summer. The juvenile survival rates of squirrels were high relative to those of hares. Degree of synchrony had no effect on survival rates of juvenile squirrels to emergence or from emergence to weaning. We suggest that predation selects for tighter reproductive synchrony of snowshoe hares, at least while they are at peak densities, but that it has little effect on the timing of red squirrel reproduction.
Oikos © 1995 Nordic Society Oikos