Seddon, P.J. and P.S. Soorae
In some cases, however, a subspecies may have become extinct in the wild and in captivity. A substitute form may then be chosen for possible release. Such substitutions are actually a form of benign introduction. Considerations include assessment of the value of a substitution project and the selection of a suit-able substitute. Species substitutions increase biodiversity, conserve related forms, improve public awareness of conservation issues, educate the public, and may be implemented for aesthetic or economic reasons. Selection of a suitable substitute should focus on extant subspecies and consider genetic relatedness, phenotype, ecological compatibility, and conservation value of potential candidates. An example of a substitution project is the reintroduction of the North African Red-necked Ostrich (Struthio camelus camelus) into areas once occupied by the now extinct Arabian Ostrich (Struthio camelus syriacus). S. c. camelus was chosen as a substitute because of its geographic proximity, phenotypic similarity, and conservation value. The World Conservation Union’s reintroduction guidelines should be consulted before a project is begun.