Projected Extinction Year and Lifetime Maintenance Costs of Captive Former Biomedical Research Chimpanzees

A vital component of small population management in captivity is forecasting future population trends. Until recently, little was known about the demographic structure of the recently retired captive former biomedical research chimpanzee population (Pan troglodytes). We used age- and sex-specific survivorship probabilities from current life tables to model the likely population extinction date and estimate total lifetime maintenance costs until extinction. Leslie matrix projections indicated that population extinction will occur in 2062 or 38 years from now. That date was 26 years longer than a recent government study of 2036, 8 years longer than the original research chimpanzee projection of 2054, and 5 years longer than our pilot projection of 2057. Median, lower, and upper quartiles of colony per diems plus median biomedical inflation were used to estimate lifetime maintenance costs. Without inflation, median lifetime expenses were USD 148.0 M, with a lower bound of USD 72.7 M and an upper bound of USD 209.9 M. With inflation, median lifetime expenses were USD 229.3 M (lower bound USD 112.7 M, upper bound USD 326.1 M). Extinction projections and associated cost estimates are essential components of any science-based small captive population management plan. These projections can be used for the long-term planning and rational management of the now-retired captive former research chimpanzee population.