No abstract

A total of 213 males and 234 females of the tiger-beetle Cephalota circumdata leonschaeferi (Cassola) were individually colour marked in the three years of study (1984, 1985, 1986). The maximum number of days in which marked individuals were resighted was 37. These tiger-beetles dispersed within a radius of 30 m from their respective marking places. Re-sightings were rare beyond this dis tance; one individual was observed at about 100 m from its marking place. The ground temperature proved to be a key-factor influencing the activity and viability of the population; optimal ground temperature ranged between 32-33°C as to number of individuals present, but a temperature of 34-35°C determined the greatest number of matings. A negative influence on C. c. leonschaeferi survival and activity was exerted by cloudy and, particularly, rainy weather. Wind force influenced the habitat selection: an increase of wind force generated a greater use of terrain without vegetation (Salicornia). Apparently the increased hunting success of these beetles in open ground at wind force 3-4 (Beaufort scale) determined the habitat selection. Males proved significantly more active than females by covering greater daily distances. Both sexes showed two peaks of activity in the early morning and in the afternoon, but they were inactive in the central hours of the day, when the ground temperatures were beyond 36-37°C. ACKNOWLEDGEMENTS