Survival rates and mortality risks of Plecturocebus cupreus at the California National Primate Research Center

Abstract

This article describes survivorship and explores factors affecting mortality risks in a captive colony of coppery titi monkeys (Plecturocebus cupreus) housed at the California National Primate Research Center (CNPRC), at UC Davis, in Davis, CA. We analyzed data collected on individuals since the colony's creation in the 1960s, with a sample of 600 animals with partially complete information (date of birth, age at death, body mass, parental lineage). We used three methods: (1) Kaplan–Meier regressions followed by a log‐rank test to compare survival in male and female titi monkeys, (2) a breakpoint analysis to identify shifts in the survival curves, and (3) Cox regressions to test the effect of body mass change, parental pair tenure, and parental age on mortality risk. We found that males tend to have a longer median lifespan than females (14.9 and 11.4 years; p = 0.094) and that survival decreases earlier in males than in females during adulthood (9.8 and 16.2 years). A body mass loss of 10% from adulthood to the time of death led to a 26% higher risk of dying (p < 0.001) as compared to an individual with stable body mass. We found no evidence of sociobiological factors on mortality risks (parental age, parental pair tenure), but an exploratory analysis suggested that a higher rate of offspring conceptions increases mortality risks. This description of factors influencing survival and mortality in titi monkeys is a first step toward understanding aging in this species to consider titi monkeys as a primate model for socioemotional aging.

Comparative lifespan and healthspan of nonhuman primate species common to biomedical research

“…23 Our estimates are 33.0 years in males and 44.0 years in females among individuals who reached ten years of age and are therefore fairly consistent with previous reports. For coppery titi monkeys, median lifespan has been reported as 14.9 years in males and 11.4 years in females among individuals surviving to 31 days, 33 compared with our estimates of 8.6 years for males and 9.2 years for females. Once again, the differences between estimates in our studies and prior reports likely arise methodologically, such as choices made about age of inclusion and use of a right censored approach to include individuals still alive and/or those euthanized for research-related endpoints.…”

“…45 The earliest age listed as adult for each species was used, supplemented by additional references for two species not present in the table, chimpanzees 46 and coppery titi monkeys. 33 Stage Two filtering also implemented a date of birth (DOB) cutoff. This step was critical for survival analyses and lifespan inference as received data did not include records on alive animals.…”

“…31 A recent study of coppery titi monkey lifespan showed a trend toward longer lifespan in males relative to females using the same population of monkeys in the current study but with different inclusion criteria. 33 It is difficult to know if the observed sex-based differences between catarrhine versus platyrrhine species are due to inherent species characteristics, institutional practices, or their interactions. For example, in catarrhine monkeys, it is common to house a single breeding or vasectomized male with multiple females.…”