A New England cottontail is shown in an outdoor captive breeding pen at the Great Bay National Wildlife Refuge in Newington.

DURHAM — An effort to raise in captivity and reintroduce into the wild the endangered New England cottontail met with success, University of New Hampshire researchers say.

“We learned that captively reared New England cottontails released in the wild bred successfully, as did their wild-born offspring,” said New Hampshire Agricultural Experiment Station researcher Adrienne Kovach, associate professor in the Department of Natural Resources and the Environment.

The reintroduction of the rabbit in Bellamy River Wildlife Management Area in Dover by wildlife biologists at New Hampshire Fish & Game and the New England Cottontail Conservation Initiative was the first such attempt, according to a UNH news release.

It is estimated there are fewer than 100 cottontails in the state today.

Doctoral student Melissa Bauer worked with Kovach to track the outcome of a reintroduction of 42 New England cottontails over five years to the Bellamy River Wildlife Management Area.

Bauer used genetic monitoring to track the released rabbits through analysis of the DNA in fecal pellets.

Of the original 42 rabbits released, six bred in the wild, along with nine of their offspring, resulting in at least 29 wild-born rabbits, according to the news release.

Integrating the genetic data with radiotelemetry data from rabbits collared by New Hampshire Fish & Game biologists Brett Ferry and Heidi Holman, Bauer and her colleagues also determined that only a small percentage of the original rabbits released survived long enough to reproduce, and survival was highest in the year of the release.

Researchers released the rabbits in late summer and early fall. Rabbits need to survive through the winter to the next spring to reproduce.

“Multiple releases of cottontails are needed to prevent negative consequences of unpredictable events, such as mortality during winter snowstorms,” Kovach said in the news release.

Conservation managers in the New England Cottontail Conservation Initiative are now applying what was learned to future rabbit releases, hoping to boost the population and increase genetic diversity.

They are experimenting with releasing cottontails earlier in the year to lessen potential seasonal effects on survival, and distribute the animals to minimize competition with rabbits that have established territories.

Managers also are experimenting with releasing rabbits that have lived in three environments: those directly from a zoo; those held for a short acclimation period in an outdoor pen; and those bred in an outdoor pen.

This research is presented in a Wildlife Society Bulletin article and has been presented to wildlife biologists and other natural resource managers in New England.

Collaborators include Holman and Ferry, who also is a UNH graduate student in the Department of Natural Resources and the Environment. Other partners include state and federal biologists and natural resource managers in the Range-wide New England Cottontail Conservation Initiative, Roger Williams Park Zoo, and the Queens Zoo.

This material is based upon work supported by the NH Agricultural Experiment Station, through joint funding of the National Institute of Food and Agriculture, U.S. Department of Agriculture, and the state of New Hampshire.

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