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as a "general benchmark," indicating that a captive breeding program may be advisable (Foose 1991, Seal 1991). Once a captive breeding program is initiated, its subsequent development can be pictured as three phases: the founding phase, during which the population is initiated; the growth phase, during which the population rapidly increases to the final size desired by its managers (the "target" population size); and the carrying capacity phase, during which the population is maintained at its target size (Figure 1) (Ballow in press). Management concerns change as the population progresses through these phases. The major concerns during each phase are discussed in turn below. Management Concerns During the Founding Phase Initially, management concerns center upon removing individuals with minimal impact on the wild population, getting the species to breed reliably in captivity, setting general goals and plans for the captive population, and obtaining enough wild individuals to ensure a sound genetic and demographic base for the captive population. Removing animals from the wild. Ways of reducing the impact of removing the captured animals from the wild population include removing eggs from nests (many birds, e.g., condors, will lay another egg to replace the one removed); capturing dispersing young, which often have a high mortality in the wild, e.g., ferrets; and TARGET SIZE CAPACITY PHASE w N V) Z 0 Q J n 0 n Husbandry Techniques Developed TIME Figure 1. The development of a generalized captive breeding and reintroduction program from the founding to the capacity phase. The captive population usually is subdivided at some point in the growth phase. 7\ Reintroduction Begins GROWTH PHASE 'IF-,Population Control Begins FOUNDING PHASE Managing Genetic Diversity ? 267