Survival patterns and mortality in the North American population of silvered leaf monkeys (Trachypithecus cristatus)

This study examines mortality in the North American (N.A.) population of silvered leaf monkeys (Trachypithecus cristatus) maintained in Association of Zoos and Aquarium's zoos. Understanding the causes of death associated with mortality rates (MR) can highlight relative susceptibility to intrinsic/extrinsic factors and differences between age and sex classes. Overall, life tables can provide insight into a species' population dynamics. We expect that the MR will fit the general mammalian and primate trends of a U-shaped curve when graphed, that males will have a higher MR and shorter life expectancy than females and that infant survival will be higher in captivity than in wild populations. Our results indicate that the N.A. captive population fits expected MR trends of a U-shaped curve. However, no differences in MR or life expectancy were found between the sexes. Infant survivorship did not differ from the wild or other leaf monkey populations (both captive and wild). The majority of infant deaths occurred on day 1 of life (52.8% of all infant deaths) and infant survivorship to 1 year was 66%. Neonates (n = 6, 31.6%) and infants (n = 4, 44.4%) died from trauma, juveniles (n = 2, 33.3%) from nutritional reasons, adults from non-infectious diseases (n = 7, 29.2%) and from post-surgical complications (n = 7, 29.2%), and older adults from idiopathic diseases (n = 4, 26.7%) and non-infectious diseases (n = 4, 26.7%). Only older adult males died from degenerative diseases (i.e., heart failure, n = 3, 42.9%). In general, this captive population demonstrated some similar trends to those observed in mammalian and Old World monkey populations.