Demography and Life Histories of Sympatric Patas Monkeys, Erythrocebus patas, and Vervets, Cercopithecus aethiops, in Laikipia, Kenya

Abstract

Mortality patterns are thought to be strong selective forces on life history traits, with high adult mortality and low immature mortality favoring early and rapid reproduction. Patas monkeys (Erythrocebus patas) have the highest potential rates of population increase for their body size of any haplorhine primate because they reproduce both earlier and more often. We report here 10 yr of comparative demographic data on a population of patas monkeys and a sympatric population of vervet monkeys (Cercopithecus aethiops), a closely related species differing in aspects of social system, ecology, and life history. The data reveal that 1) adult female patas monkeys have significantly higher mortality than adult female vervets; 2) infant mortality in patas monkeys is relatively low compared to the norm for mammals because it is not significantly different from that of adult female patas monkeys; and 3) infant mortality is significantly higher than adult female mortality in vervets. For both species, much of the mortality could be attributed to predation. An epidemic illness was also a major contributor to the mortality of adult female patas monkeys whereas chronic exposure to pathogens in a cold and damp microenvironment may have contributed to the mortality of infant vervets. Both populations experienced large fluctuations during the study period. Our results support the prediction from demographic models of life history evolution that high adult mortality relative to immature mortality selects for early maturation.

Infant Mortality in Black-and-Gold Howlers (Alouatta caraya) Living in a Flooded Forest in Northeastern Argentina

“…Infant mortality in wild populations of nonhuman primates may result from a decrease in the seasonal availability of foods required by the infant's mother, leading to a decrease in milk production (Roberts et al 1985); a decrease in food availability caused by natural disturbances such as cyclones, droughts, and floods (Cheney et al 2004;Dittus 1988;Gould et al 1999;Pavelka et al 2007;Tecot 2010); immature development of the infant's immune system resulting in an increased susceptibility to diseases or parasite loads (Brain and Bohrman 1992;Holzmann et al 2010;KalemaZikusoka et al 2002;Kuntz 1982); elevated levels of predation risk (Boinski 1987;Isbell et al 2009;Miller and Treves 2011;Nishida et al 1985;Oversluijs Vasques and Heymann 2001;Sampaio and Ferrari 2005); conditions promoting opportunities for infanticide (Cords and Fuller 2010;Crockett 2003;Fedigan 2003;Sherrow and Amsler 2007;Swedell and Tesfaye 2003;Valderrama et al 1990;Van Belle et al 2010;Watts et al 2002;Zunino et al 1986); maternal age or inability of inexperienced mothers to care for their offspring (Cheney et al 2004;Clarke and Glander 1984); changes in female dominance resulting in increased infant kidnapping (Isbell et al 2009;Shopland and Altmann 1987); and random accidental events such as falls (Nakamichi et al 1996;Serio-Silva and Rodriguez-Luna 1994).…”

Do Forest Composition and Fruit Availability Predict Demographic Differences Among Groups of Territorial Owl Monkeys (Aotus azarai)?

“…Niche diversification, interspecific competition, predator pressure, disease, parasites, and habitat contraction and expansion are additional factors that can influence primate population dynamics (Fleagle and Reed 1996;Holzmann et al 2010;Isbell et al 2009;Rudran and Fernandez-Duque 2003;Struhsaker 2008). Sometimes, several factors can influence a population simultaneously, such as habitat contraction and variations in interspecific competition (Vitazkova and Wade 2007).…”

Life History of Cercopithecus mitis stuhlmanni in the Kakamega Forest, Kenya

“…Isbell et al (2009) recently compared the 2 open-country forms, vervet (Chlorocebus aethiops) and patas monkeys (Erythrocebus patas), and related differences in their life histories to differences in mortality patterns. Here, we present the first extensive life history data set from a highly arboreal, forest-dependent guenon, the blue monkey (Cercopithecus mitis stuhlmanni).…”

“…These data allow us to extend the comparison of Isbell et al (2009) within the cercopithecin tribe (the guenons) to a markedly different habitat, and thus to evaluate further the importance of mortality patterns in predicting fast vs. slow life histories. In addition, and from a broader perspective, whereas most life history studies of natural populations in the cercopithecine subfamily have focused on terrestrial or semiterrestrial species living in relatively seasonal and unpredictable savannah-woodland habitats (Table I), our report contributes data from an arboreal forest-dwelling species, most of which remain poorly known, especially in nature (Ross 1998).…”