Robert Eric Ricklefs (born June 6, 1943) is an American ornithologist and ecologist.

His doctoral advisor was originally Robert H. MacArthur (prior to his move to Princeton University), but he finished his dissertation under W. John Smith.

He completed a year as a postdoctoral fellow at the Smithsonian Tropical Research Institute in Panama before taking up a faculty position at the University of Pennsylvania.

[6] During his career,[7] he has made major contributions to the island biogeography, including testing E. O. Wilson's Taxon Cycle Concept,[8] His most-cited scientific paper examined ecological communities.

His original method for avian growth rate estimation[11] continues to be used today though modifications have been proposed.