Rational (Sustainable) Use of Waterfowl Resources: Demographic Status of the Population and Harvest Rates

Abstract—

In our previous article, a so-called “mortality pattern” was considered: the graphic ratio of the theoretical and real rate of decrease in the number of birds in the cohort considered by years. In this report, a numerical index of the population demographic status is derived based on the mortality pattern obtained from bird ringing data. This index is the mean deviation of the real mortality from the theoretical one calculated with a number of conditional restrictions and using additional coefficients. The degree of waterfowl population demographic status (the population size is stable, decreasing or growing) was estimated in two ways: using the numerical index derived and based on large-scale accounting and observations in nature. A good coincidence of both estimations was demonstrated for almost all waterfowl species. The numerical index of the population demographic status is proposed as one of the criteria for estimating the rational use of hunting species. This index allows us to make a conclusion about the possibility of hunting of various species of waterfowl birds or about the need for their protection (together with an indication of the required security measures). Based on calculations from bird ringing data, the harvest rate for those hunting species, the demographic status of which allows it, is substantiated. The harvest rate of waterfowl hunting species should not exceed one-third of the annual mortality rate for adult mature birds, no more than 67% for first year ducks, and no more than 45% for first year geese. Based on the method applied, it was possible to calculate the harvest rate for each hunting species of waterfowl, depending on the portion of yearlings in the population at the time of autumn surveys.