RESOLUTION OF SPATIAL COMPLEXITY IN A FIELD SAMPLE OF SINGING CRICKETS TELEOGRYLLUS-COMMODUS (WALKER) (GRYLLIDAE) - A NEAREST-NEIGHBOR ANALYSIS

The nearest-neighbour distances for a sample of singing crickets were analysed for spatial pattern using a goodness-of-fit test. There was an excess of individuals in the lower and upper tails of the distribution, indicating aggregation of some crickets, and a spacing out of thers. Regularity within the aggregated component was also demonstrated, using the Pielou (1962, J. Ecol., 50, 357-367) test for competition. Thus, to obtain an overall analysis of spatial pattern of the sample, both tests were required. The presence of aggregation together with regularity in a population results in a loss of sensitivity of the Clark & Evans test (1954, Ecology, 35 445-453) and the Thompson test (1956, Ecology, 37, 391-394) because for these single-component tests the effects of opposing deviations from randomness can cancel out. This was illustrated by applying the tests to a synthetic sample, and to the sample of singing crickets. A computer program NN-TESTS was used for the analyses. The behavioural significance of the spacing in crickets is discussed. © 1990 The Association for the Study of Animal Behaviour.