Parental care by lone male Ferruginous Hawks ( Buteo regalis ), Rough-legged Hawks ( Buteo lagopus ), and Great Horned Owls ( Bubo virginianus ) was limited to providing food

In three long-term studies of Ferruginous Hawks ( Buteo regalis ), Rough-legged Hawks ( Buteo lagopus ), and Great Horned Owls ( Bubo virginianus ), we observed rare but regular occurrences of superabundant prey at nests where nestlings were hungry, emaciated, or dead. In these cases, a male appeared to be the lone parent; the female parent was found dead, kept away by disturbances, or simply absent. We conclude that the male parents, whose normal role is to provide food, were unable to expand their care to include morseling, feeding, and brooding. Faced with the stress of incessant food begging by nestlings, the male parents responded by bringing more and more food to the nest, to the point where food spoiled while the young starved amid plenty. We provide and interpret detailed observations for 11 such cases and suggest several variables that would influence the nestlings’ chances of survival.