Effectiveness of population recovery projects based on captive breeding

A recovery programme for a population of Apollo butterflies in the Pieniny National Park was monitored over 12 years in order to assess its effectiveness. The programme was based on population ecology and metapopulation theory, and its object was to replenish wild populations with captive-reared individuals. Thanks to the adopted measures, the local population initially numbering only 30–50 individuals increased to ca. 1000 imagines, forming a functional metapopulation. Nevertheless, analysis of population dynamics parameters indicated that only some of the subpopulations were stable; a significant percentage of the subpopulation fractions represented sink populations whose survival depended either on an external supply of captive-reared individuals or on individuals from other source subpopulations. In some cases, intensively supplying the subpopulation with captive-reared individuals resulted in a decrease of that deme’s abundance.The results suggest that supplying captive-reared individuals to an endangered population may entail some risks and should be done with caution.