The 'hidden' life of an ecosystem engineer Morgan Kelly, High Meadows Environmental Institute June 1, 2021 10:15 a.m. For his senior thesis, Joe Kawalec of the Class of 2021, who graduated Princeton with a bachelor’s degree in ecology and evolutionary biology with a certificate in environmental studies, studied the natural camouflage of downy woodpeckers to understand how it helps the small bird survive in its forest habitat. Photo by Morgan Kelly, High Meadows Environmental Institute The two years Princeton senior Joe Kawalec spent studying the natural camouflage of the ubiquitous downy woodpecker oddly enough began and ended the same way — tracing the outlines of birds.