kleptoparasitism

thumb|upright=1.35|Great frigatebirds (Fregata minor) chasing a [[red-footed booby (Sula sula) to steal its food]] Kleptoparasitism (originally spelt clepto-parasitism, meaning "parasitism by theft") is a form of feeding behavior in which one animal — i.e. the kleptoparasite — deliberately takes food from another animal, often via aggressive confrontations. The strategy is evolutionarily stable when stealing is less costly than direct predation, such as when food is scarce or when physically weaker/less assertive victims are abundant and unlikely to fight back.

Many kleptoparasites are arthropods, especially bees and wasps, but including some true flies, dung beetles, bugs and spiders. Cuckoo bees are specialized kleptoparasites which lay their eggs either on the pollen masses made by other bees, or on the insect hosts of parasitoid wasps. They are an instance of Emery's rule, which states that insect social parasites tend to be closely related to their hosts. The behavior also occurs among vertebrates including birds such as skuas, who persistently chase and harass other seabirds until they disgorge their food; and hypercarnivorous mammals such as spotted hyenas and lions, who routinely rob killed prey from each other and other mesopredators such as cheetahs. Other species might also opportunistically indulge in kleptoparasitism, especially when driven by the desperation of hunger and when scavenging isn't an option.