Implications of the prevalence and magnitude of sustained declines for determining a minimum threshold for favourable population size.

摘要: We propose a new approach to quantifying minimum threshold value for the size of an animal population, below which that population might be categorised as having unfavourable status. Under European Union law, concept Favourable Conservation Status requires assessment populations favourable or status, but quantitative methods such assessments have not yet been developed. One is well established in conservation biology viable (MVP) defined small stable with acceptably low risk extinction within specified period. Our combines this small-population paradigm MVP multiplier, factor by multiplied allow sustained future decline. demonstrate using data on UK breeding bird sizes. used 43-year time-series 189 species and qualitative trends over almost 200 years 229 examine prevalence, duration magnitude declines. study addressed problem underestimation declines caused short runs monitoring allowing truncation time series. The multiplier was derived from probability distributions decline magnitudes given period, adjusted truncation. Over surveillance period 100 years, we estimated there 10% across at least sixteen-fold would begin. therefore suggest that, case, 16 could MVPs obtain sizes ‘MVP Multiplier’ method robust obtaining integrates concepts declining-population paradigms. intended use alongside range other measures enable overall