Individual study: Limits to captive breeding of mammals in zoos
Alroy J. (2015) Limits to captive breeding of mammals in zoos. Conservation Biology, 29, 926-931
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Breed mammals in captivity
A review of captive-breeding programmes in 1970-2011 across the world (Alroy 2015) found that the majority of 118 captive-bred mammal populations increased in size. The average annual rate of population increase was 0.028, and only 17 populations (14%) declined (five ‘endangered’ or ‘critically endangered’ according to the IUCN Redlist). Authors reported that positive growth rates were maintained for a large majority of the populations in all IUCN categories except those of ‘least concern’. However, average growth rates declined from 1970-1991 (0.054) to 1992–2011 (0.021). Authors reported that there was a slight decrease in average death rate of populations over time and either no change in average birth rate, or lower birth rates after 1989. Population growth rates did not vary with body mass, but were reported to decrease as the ratio of individuals in programs to populations increased (see original paper for details). Counts of births, deaths and end-of-year totals of individuals in captive populations recorded in studbooks (excluding regional studbooks) were published in the International Zoo Yearbook. Those published from 1970 to 2011 were used to calculate rates of population growth for 118 captive-bred populations (81 species and 37 subspecies). Only populations for which the sum of end-of-year totals was at least 250 over the time period were included.
(Summarised by Rebecca Smith)