Invasive Rabbits: Maine Islands Eradicated Snowshoe Hares

The natural landscape of Maine's Bay of Fundy Islands has finally returned to normal, after conservation experts eradicated all invasive snowshoe hares in 2007. Hay Island, located at the mouth of the bay, just 15 miles off the coast of Maine was stocked with the rabbits in 1959 by fishermen looking for a subsequent source of income and a new winter hobby. However, with no competition and few predators, snowshoe hares multiplied and spread to nearby Kent Island, where they quickly became invasive pests.

Here's the scenario before things got back to normal: The island, once rich with forests of red and white spruce, balsam fir, tamarack, heart-leafed and yellow birch, mountain maple and mountain ash, was reduced to wood fern and raspberry, which crowded other plants and provided hares with a place to hide from bald eagles and wintering snowy owls lurking overhead. 

"The island's forests were becoming transformed into open tangles," Nat Wheelwright, professor of Natural Sciences at the Bowdoin Biological Field Station on Kent Island, said in a statement. 

Furthermore, the loss of trees threatened several forest-breeding birds, including the island's population of Leach's storm petrels, whose population has been continuously monitored since 1954.

Snowshoe hares were able to spread beyond the limits of Hay Island, onto Kent Island when low tide opened a sort of "land bridge" or causeway for the animals to hop across. The rabbits are native to North America and range across the north of the continent from Alaska to the coast of Maine.

However, they would have never made their way to the remote islands of the Bay of Fundy had they not been given some human assistance. Researchers raised concerns as populations grew 3-50 times as large as those those found on the mainland of Maine.

"Something had to be done to control the snowshoe hares," Wheelwright added. "Authorities on pest control recommended poisons, viruses, antifeedants (pesticides), falconers, traps, lynx, dogs and professional hunters."

Whellwright opposed the use of viruses and poisons, as they can jeopardize other species, as well as the use of non-native predators, such as lynx or dogs -- because the latter would threaten the islands' seabird colony.

In 1998, Wheelwright launched a hunting and trapping program. However, in a matter of two years the snowshoe hares did indeed reproduce like rabbits, and their population resurged to its former size. Another failed attempt to control the population was made in 2002.

Not willing to give up, Wheelwright turned to another country's experiences, talking with the head of New Zealand's office of vertebrate control. That office is famous worldwide for having eliminating problem species from islands. Encouraged to try harder, he finally successfully trapped the last hare in 2007. 

"The response of the plant community to the elimination of an introduced keystone herbivore was immediate and dramatic," he said, adding that many young trees now blanket the island's forest floor, and more young trees are bolting skyward. "Boreal forests that have long provided nesting habitat for birds and other animals are now able to recover and flourish."

Their findings were recently published in the journal Frontiers in Ecology and the Environment. 

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