Meanwhile, white-tailed deer eat little else but acorns when mast is abundant and many of them are infested with adult ticks that were picked up in brushy hangouts. The ticks mate, the females drop off to lay their eggs in the leaf litter and the pinpoint-size larvae hatch the next summer at a time when the oak woods are overrun with mice, which are the favorite host for young ticks. The nymphs then molt into adult ticks, hitch a ride back to the woods and the cycle begins anew. The risk of getting Lyme disease is highest the second year after a big acorn crop. Ostfeld also notes that white-footed mouse population explosions affect other species.
Mice also eat the eggs of ground-nesting birds like juncos and ovenbirds.
Seeds of species that are replacing oaks, primarily red maple, sugar maple, sweet birch and yellow poplar, are of considerably less value to wildlife than acorns. Hardwood forests in some regions are being ground up by gigantic chip mills that supply wood chips to papermakers as far away as the Pacific Rim. Deer populations that sometimes exceed 30 animals per square mile eliminate oak seedlings. Stress from drought and defoliation makes oaks vulnerable to attacks by fungi and boring insects. And fires that would kill competing trees but not oaks, which have thick bark and deep roots, are quickly extinguished.