Tree Recruitment Limitation by Introduced Snowshoe Hares, Lepus americanus, on Kent Island, New Brunswick

Abstract

Species introductions often have negative consequences for native plant and animal communities of islands. Herbivores introduced to islands lacking predators can attain high population densities and alter native plant communities by selective consumption of palatable plants. We examined the legacy of the 1959 introduction of Snowshoe Hares (Lepus americanus) to Kent Island, New Brunswick, by reconstructing a history of tree recruitment on Kent Island and on nearby Outer Wood Island, which lacks Snowshoe Hares. Tree-ring records show pronounced recruitment peaks associated with farm abandonment in the 1930s for Kent Island and in the 1950s for Outer Wood Island. Following the introduction of Snowshoe Hares to Kent Island, tree recruitment plummeted and has remained low ever since. In contrast, trees continued to establish throughout the latter 20th century on Outer Wood Island. The high rates of seedling mortality on Kent Island associated with Snowshoe Hare browsing coupled with high rates of canopy tree mortality threaten to degrade severely the forest of this important seabird nesting sanctuary.