The effect of demographic characteristics on the success of ungulate re-introductions

• Published in: Biological conservation 2000-04, Vol.93 (2), p.187-193
• Main Authors: Komers, Petr E., Curman, G.Peder
• Format: Article
• Language: English
• Subjects: Animal, plant and microbial ecology; Applied ecology; Artiodactyla; Biological and medical sciences; Conservation; Conservation, protection and management of environment and wildlife; Fundamental and applied biological sciences. Psychology; Parks, reserves, wildlife conservation. Endangered species: population survey and restocking; Population structure; Rate of increase; Re-introduction; Ungulate
• ISSN: 0006-3207; 1873-2917
• DOI: 10.1016/S0006-3207(99)00141-X

Given that small populations are susceptible to extinction and inbreeding, a primary goal of re-introductions should be to maximize the initial rate of increase of a re-introduced population. We investigated how the rate of increase of newly re-introduced populations of artiodactyl species was affected by population characteristics, such as their size, sex-, and age-structure. While selecting the data of past re-introductions for our analysis, we controlled for factors that are known to affect success. The growth rate r of the populations increased with the number of animals released, up to about a population size of 20, at which point an asymptote was reached. All larger populations grew at a median r=0.17, while several smaller populations declined. Small populations grew faster if they contained more mature individuals. Small, heavily female-biased populations were more variable in r than those of a more equal sex ratio. These female-biased populations also grew on average less well. Generally, populations of