OBSERVED ACTS OF EGG DESTRUCTION, EGG REMOVAL, AND PREDATION ON NESTSOF PASSERINE BIRDS AT DELTA MARSH, MANITOBA

I describe 13 observed acts of predation on eggs and nestlings of seve n passerine bird species,witnessed from 1978 to 1992 in the forested d une ridge, Delta Marsh, Manitoba. The predators were two mammals (weas el, Mustela sp.; American Red Squirrel) and two birds (Black-billed Cu ckoo and Common Grackle). In addition, I describe five acts of egg rem oval by the Brown-headed Cowbird (four by females, one by a male), one act of egg destruction and two attempts by House Wrens, two acts of e gg destruction by Gray Catbirds, and single acts of egg destruction by a Red-winged Blackbird, Yellow-headed Blackbird, and Northern Oriole. I examine behaviour of the attendant adults at nests under attack, ou tcomes of predatory nets, i.e., partial or total destruction of clutch es or broods, condition of nests after predation, and response of vict imized adults, i.e., desertion or tolerance of the disturbance.