But Doug Inkley , senior scientist at the National Wildlife Federation , said that wild animals can be resilient when their usual food sources go away . People are affected this fall by a shortage of acorns in the eastern U.S . Residents in some areas have plenty of trees , while others have seen none at all . Tree growth runs in cycles , so a lean year may be normal after last year 's big crop . Some people fear the shortage will affect their populations .
People are affected this fall by a shortage of acorns in the eastern U.S . Residents in some areas have plenty of trees , while others have seen none at all . Tree growth runs in cycles , so a lean year may be normal after last year 's big crop . Some people fear the shortage will affect their populations .