Territorial Preferences of the Hilltopping Wasp Hemipepsis ustulata (Pompilidae) Remain Stable from Year to Year

Abstract Males of the tarantula hawk wasp Hemipepsis ustulata defend individual trees and shrubs on mountaintops in central Arizona where they wait for arrival of sexually receptive females. Each spring, a new generation of males comes to prominent hilltops to compete for mating territories. In 4 of 5 years during 1997–2007, in which the same Arizonan peaktop was censused regularly, behavior of males was similar with respect to such things as total number of plants occupied by territorial males, average number of days in which site-faithful males returned to their territories, and mean maximum days of residency at those select sites that attracted at least one male for a period of ≥2 weeks. Territories that regularly attracted males in one year did so in other years as well; territories that were infrequently occupied in one year were defended only occasionally, if at all, in other years. Even in the year (1998) when an unusually large number of plants were selected as perch territories by male wasps, preferred sites (those most consistently occupied over the flight season) remained the same as in the more typical years. Perhaps because the position and relative conspicuousness of the slow-growing mature trees and shrubs on hilltops remains the same from year to year, perch preferences of males also remain constant over long periods.