Pollen Digestibility by Hummingbirds and Psittacines

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Abstract
Pollens fed to adult and nestling hummingbirds were largely unaffected by passage through the digestive tracts. Adult lorikeets and Cockatiels (Nymphicus hollandicus) responded similarly, but their nestlings were somewhat more able to digest pollens. Eucalyptus, Zauschneria, and Callistemon pollens were fed to nestling and adult Anna''s Hummingbirds (Calypte anna) and adult Costa''s Hummingbirds (C. costae). Eucalyptus and Prunus pollens were fed to adult Rainbow Lorikeets (Trichoglossus haematodus haematodus), adult and nestling Moluccan Lorikeets (T. h. moluccanus), and adult and nestling Cockatiels. Empty grains were considered to be digested. Hummunigbirds digested less than 7% of all the pollens fed. Adult lorikeets digested less than 7% of the Eucalyptus pollen, and nestlings digested 24%. Adult Cockatiels digested 17% and nestlings 38% of the Eucalyptus pollen. Neither psittacine digested more than 4% of the Prunus pollen. It was concluded that the pollens did not furnish a significant source of energy or protein to the birds.