THE TEMPORAL VARIABILITY OF ANIMAL ABUNDANCES - MEASURES, METHODS ANDPATTERNS

From first principles, the temporal variability of a time series of ab undances can be defined as the average deviation of values from a mean value on a proportional scale. In this paper we review: (i) the diffe rent kinds of temporal variability; (ii) the different ways in which i t can be measured; (iii) the design of appropriate sampling schemes; ( iv) methods of analysing variability; and (v) patterns in temporal var iability. We emphasize that some commonly applied measures are not app ropriate, that several do not measure the desired feature of time seri es, and the importance of considerations of trend and sampling error. A number of suggestions are made for the improvement of the basis for comparative analyses of levels of variability, and some of the potenti al pitfalls are identified. Given the serious faults in many previous analyses of ecological patterns in the temporal variability of animal abundances, emphasis is laid on the theoretical basis for different pa tterns, and hence a set of hypotheses for testing is generated.