Jones CB (1997) Life-history patterns of howler monkeys in a time-varying environment. Biol. Primatol. Lat. 6(1): 1-8.
Abstract: This report examines the relationship between life-history characteristics and environmental predictability for mantled howler monkeys (Alouatta palliata palliata Gray) at Hacienda La Paccifica, Guanacaste Province, Costa Rica. A census with age structure was employed to estimate life-history parameters [calculations of life table after Wilson & Bossert, 1971] including survivorship, fecundity, and mortality, [& generation time]. A time-series analysis of yearly rainfall at La Pacifica was conducted to test inferences from life-history theory whereby variations in mortality across the lifespan [across age stages] are a function of environmental predictability. La Pacifica was found to be a relatively predictable environment, and, consistent with theory, howlers exhibit life-history traits expected for their regime. These include low survivorship during more than one age class, iteroparity, a relatively small reproductive effort, a single young per litter, relatively few young across a lifetime, and relatively long lifespan. The predictable environment of howlers at La Pacifica appears to favor adult over juvenile (including infant) survival, and howler life history is consistent with that for other large mammalian herbivores whose females may time reproductive investment to reduce the [deleterious] effects of environmental heterogeneity ("bet-hedging"). [A moving average model of the rainfall data is provided in the paper.]
Reference
Wilson EO, Bossert WH (1971) A primer of population biology. Sinauer Associates, Stamford, CT.
Abstract: This report examines the relationship between life-history characteristics and environmental predictability for mantled howler monkeys (Alouatta palliata palliata Gray) at Hacienda La Paccifica, Guanacaste Province, Costa Rica. A census with age structure was employed to estimate life-history parameters [calculations of life table after Wilson & Bossert, 1971] including survivorship, fecundity, and mortality, [& generation time]. A time-series analysis of yearly rainfall at La Pacifica was conducted to test inferences from life-history theory whereby variations in mortality across the lifespan [across age stages] are a function of environmental predictability. La Pacifica was found to be a relatively predictable environment, and, consistent with theory, howlers exhibit life-history traits expected for their regime. These include low survivorship during more than one age class, iteroparity, a relatively small reproductive effort, a single young per litter, relatively few young across a lifetime, and relatively long lifespan. The predictable environment of howlers at La Pacifica appears to favor adult over juvenile (including infant) survival, and howler life history is consistent with that for other large mammalian herbivores whose females may time reproductive investment to reduce the [deleterious] effects of environmental heterogeneity ("bet-hedging"). [A moving average model of the rainfall data is provided in the paper.]
Reference
Wilson EO, Bossert WH (1971) A primer of population biology. Sinauer Associates, Stamford, CT.