• Mate finding;
  • population density;
  • field cricket;
  • Gryllus campestris;
  • field study

Abstract. 1. Members of a field population of Gryllus campestris L. varied in their walking and calling activity. In both sexes, some individuals occupied burrows whereas others walked around in the observation area. Males at burrows could be either silent or calling.

2. In the course of one summer, population density decreased and the initial balanced sex ratio changed to a large surplus of males.

3. At high population density, there were equal numbers of non-calling males at burrows, calling males at burrows and walking males, while walking females predominated over females at burrows. Non-calling males at burrows achieved more encounters with females than did calling and walking males. Females met males by walking through the population and by waiting at burrows. Thus, calling and phonotaxis were not essential for mate finding and calling was less effective than previously thought.

4. At low population density calling males predominated. Calling males at burrows achieved the most encounters with females. Females met males only by walking around in the population area. Calling was thus more important in mate finding than at high population density.

5. Changes in sex ratio and population density may cause the flexibility in mate finding behaviour of individual crickets.