PARKS OR ARKS - WHERE TO CONSERVE THREATENED MAMMALS

Growing deterministic and stochastic threats to many wild populations of large vertebrates have focused attention on the conservation signif icance of captive breeding and subsequent reintroduction. However, wor k on both gorillas and black rhinos questions this shift in emphasis. In these species, field-based conservation can be effective if properl y supported and, although this is not cheap, per capita costs may stil l be considerably lower than for ex situ propagation in captivity. Her e we attempt to broaden the scope of this debate by contrasting the br eeding success and costs of in situ and captive programmes for a range of threatened mammals. Data are scarce, but we find that across nine large-bodied genera, in situ conservation achieves comparable rates of population growth to those seen in established captive breeding progr ammes. Moreover, comparing budgets of well-protected reserves with toe s' own estimates of maintenance costs and the costs of zoo adoption sc hemes, we find that per capita costs for effective in situ conservatio n are consistently lower than those of maintenance in captivity. Capti ve breeding may be more cost-effective for smaller-bodied tars and wil l often remain desirable for large mammals restricted to one or two vu lnerable wild populations. However, our results, coupled with the fact that effective in situ conservation protects intact ecosystems rather than single species, lead us to suggest that toes might maximize thei r contribution to large mammal conservation by investing where possibl e in well-managed field-based initiatives, rather than establishing ad ditional ex situ breeding programmes.