Open-pit mining procedures being conducted in the oil sands of northeast Alberta greatly disrupt many acres of the environment. The reclamation and afforestation program intended to restore the forest habitat encountered an unanticipated problem when a large percentage of young nursery-raised trees planted on a tailings pond dyke and on overburden dump sites were found to have been girdled by a population of meadow voles which had become established in the dense grass habitat created to stabilize steep sandy slopes of the spoil piles. The study monitored small mammal populations through a high, low, and a second high level commensurate with the 3- to 4-year population cycle of small mammals. A control technique utilizing grain treated with an anticoagulant rodenticide made available to the mice in poisoned bait feeder stations effectively reduced small mammal numbers to very low levels and reduced girdling damage from an average of 50 percent to 1-2 percent. Forest Sci. 26:687-702.