Common use of Population size Clause in Contracts

Population size. This is one of the fundamental attributes used to assess the status of a flyway population. The sizes of waterbird populations are constantly changing, yet population size estimates are usually only measured periodically (updates once in every 3-12 years). Therefore, it is important to use metrics that provide the best characterisation of the population size until the next assessment. If the population is fluctuating, the best characterisation of the ‘current’ population size is to present the five-year mean of the population estimate +/- the 95% confidence intervals (if a sufficient number of annual surveys have taken place). In the case of populations that are clearly increasing or decreasing, the five-year mean would be a biased characterisation of the ‘current’ population size, therefore the five-year maximum or minimum is used, respectively. When the population estimate is not based on yearly counts, but only minimum and maximum estimates are available, the geometric mean of these two values is used because it provides a more robust estimate of the population size than the arithmetic mean.