National Geographic : 1993 Jun
"How many little dramas are enacted in the depth of the woods at which man is not present," Henry David Thoreau wrote while pondering blue jays-the roguish robbers of orioleyoung (left). Predationis a vio lent hurdle to successful nesting in the U. S ., where jays, crows, rac coons, and squirrelsall feed on migrantsongbird eggs and hatchlings. Forestfragmentation only worsens the car nage. Fattenedon birdseedor garbage, predatorsboom wher ever suburbiameets woodlands. "Nice cuddly chipmunks can be aggres sive raiders,"notes ornithologistRichard Holmes, who has placed decoy nests in New Hampshireforests to study predatorssuch as the mink-like fisher (above). His work shows that nesting losses for one migratory songbird, the American redstart, can reach 70 percent. Resident birds like woodpeckers or chicka deesfare better against nestpiracy-theyfight off attackersmore often, andthey lodge in safer tree holes.