Association of Pica magpies with grazing ungulates: a clue to the genus’ origins

The habits of Pica in the less man-modified of its various habitats and its similarities with the closely related Ptilostomus suggest that association with wild ungulates has been crucial in the evolution of the genus. The shape and colours of (sub-)tropical forest ancestors may have served as pre-adaptations for the association with steppe ungulates in periods of colder and drier climate in south-eastern Asia, within the present-day range of the basal form of sericea. Subsequently, through symbiosis with several ungulate species, Pica may have reached a Holarctic distribution. Retention of the ancestral traits may have permitted Pica to re-adapt to milder climates at the margins of its range, and thus produce ecologically different, though morphologically still similar, populations. Its flexible association with large mammals, mainly used as indirect food sources, may finally have led Pica to adapt to life with humans, even in largely artificial environments, provided that they still offered some short grass to forage in.