Endangered Species Recovery Calculator

Lambda (the annual growth multiplier) is calculated as adult survival plus a separate recruitment term for new breeding-age adults, so adult survival contributes directly and additively to lambda. Raising it, holding the breeding rates fixed, always pushes lambda higher, since nothing else in the formula works against that term.

Lambda below 1.0 means the population is shrinking every year regardless of how many breeding pairs currently exist, because deaths and low recruitment outpace births surviving to breeding age. A population in this state will never reach a recovery target larger than its current size without a change in survival or recruitment rates.

Ne measures the genetically effective breeding population, which is typically smaller than the raw census count and drives how fast genetic diversity is lost each generation. A population can be numerically recovering while still losing genetic diversity quickly if its effective population size stays small relative to its census size.

It's a widely cited conservation genetics guideline suggesting roughly 50 individuals are needed to avoid immediate inbreeding depression and roughly 500 to retain long-term evolutionary potential and adaptability. It's a general planning threshold, not a guarantee that any specific population above those numbers is genetically secure.

The projection assumes lambda stays constant for the full ten years, which real populations rarely do — environmental variability, disease outbreaks, habitat change, and density-dependent effects as a population approaches carrying capacity all shift survival and recruitment rates over time, so treat the projection as a planning baseline, not a forecast.