Mark Hauber undertook this project as part of his senior thesis in Organismal Biology, for which he received exceptional distinction upon graduating in 1996.Delayed plumage maturation is knows as the phenomenon whereby young but sexually mature birds display an intermediate plumage between those of juveniles and those of older breeding adults. But why should breeding-age birds signal their age?Mark studied this phenomenon in the Black-throated Blue Warblers at Hubbard Brook Experimental Forest, in the White Mountains of New Hampshire, collaborating with Dartmouth’s ecology professor Richard Holmes. Mark spent each day surveying the forest for new nests originated by female warblers and assessed whether earlier-nesting females were mated to older or younger males in the territory. The results were suggestive of younger birds arriving later and beginning to breed with less time to spare during the short breeding season in New Hampshire. After graduating, Mark went onto obtaining a PhD focusing on bird behavior at Cornell University and was a postdoctoral fellow at UC Berkeley. Today he works as professor and associate provost for research at Hunter College in the City University of New York (www.cowbirds.org) .