Theft of prey cicadas from Pacific cicada killers (Sphecius convallis Patton) by birds

Provisioning by the Pacific cicada killer (Sphecius convallis Patton) was observed in a large nesting aggregation located on a sand dune in southern Arizona (Santa Cruz County). Many prey items, all Tibicen parallelus Davis, were stolen from the wasps by birds. Thirty-nine instances of kingbirds (Cassin's and Thick-billed) were recorded successfully stealing cicadas from provisioning female cicada killers. About 70% of kingbird attacks on provisioning wasps was successful. Kingbirds carried out a successful theft every 19.4 min, and the number of successful attacks was equal to the number of successful provisionings observed during the observation periods. The kingbirds usually perched on top of a mesquite bush or near the top of a dead agave bloom at the periphery of the sand dune, providing them with a good view of any approaching provisioners. At times there were as many as five kingbirds thus perched. The kingbird generally flew out, seized the cicada in its bill and returned to the periphery, landing on an agave bloom or mesquite. A successful kingbird attack often was followed by the bird beating the cicada against a branch (67% of cases) before consuming it. Prey theft by greater roadrunners (9 cases) was also recorded; however, their method differed from that of kingbirds. Roadrunners walked the periphery of the dune, where most of the burrows were located, generally staying in the shade. When a provisioning wasp landed, the roadrunner ran to it and grasped the cicada in its bill before the wasp could enter its burrow. The roadrunner sometimes tossed the cicada a few times before swallowing it. Given the low provisioning rate observed during this particular field season, theft of prey by birds may have had a significant impact on the cicada killer population size in the next generation.