Born in 1943, he grew up near Monterey, California, where his interest in biology was fostered by a teacher.

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.