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MORTALITY AND POPULATION CONTROL
Author(s) -
Southern H. N.
Publication year - 1959
Publication title -
ibis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.933
H-Index - 80
eISSN - 1474-919X
pISSN - 0019-1019
DOI - 10.1111/j.1474-919x.1959.tb02399.x
Subject(s) - population , mortality rate , biology , demography , population control , birth rate , ecology , abundance (ecology) , starvation , population density , zoology , fertility , research methodology , family planning , sociology , endocrinology
Summary.1 There are two main views about the relative importance of birth‐ and death‐rates as density‐dependent regulators of bird populations. One holds that the death‐rate is the important variable, the other that the birth‐rate, by declining, if necessary, to zero, can regulate a population at a level below the danger of starvation. 2 Some general considerations are advanced which, in the writer's opinion, indicate that mortality is the more important control factor. 3 Preliminary figures are given from a study of a Tawny Owl population, which show that the success of their breeding in any year is closely linked with the abundance of the rodents upon which the owls feed. Prevention of breeding and losses of eggs and chicks occur on a substantial scale and are thought to be directly attributable to lack of food. 4 From the details given the conclusion is drawn that density‐dependent mortality of this type is a widespread regulator of bird populations and may be important even in populations which appear to control their own level by e.g. territorial spacing.