Thimble Islands - Environment

Environment

As with most of southern New England, the ecology of the islands have been heavily influenced by thousands of years of intermittent human occupation. One particularly intrusive event was the toppling of all the trees on every island during the American Revolutionary War to eliminate hiding places for British ships.

The plant species of the islands were extensively studied by Yale botanist Lauren Brown; although the islands represent a unique ecological niche, combining a thin layer of soil, a high concentration of salt, and extreme exposure to weather, no unique, unusual, or rare plant species have been found; instead, the shrubs and trees represented are generally similar to those on the nearby mainland, selecting only those that reproduce by berries or other fruit carried by birds to the islands, for example raspberries, blackberries, sassafras, cherries, etc. The exception is large stands of pitch pine, whose airborne seeds are apparently able to travel from the mainland. Poison ivy has established itself in many sites on the islands, in some places thick enough to forbid entire areas from human intrusion.

In contrast to the mainland, oaks are particularly absent, even though blue jays are capable of ingesting acorns and carrying them from place to place. Nevertheless, some infrequent oak, maple, beech, and other trees do appear in scattered locations about the islands; from their locations they appear to have been deliberately planted by residents, or they are the descendants of such plantings. Other cultivated plants, such as ivy and some types of climbing roses, have established themselves on the islands to the point of becoming invasive species.

Mammals other than human beings are generally not found on the islands; although a rare squirrel or deer may be seen, they appear to be isolated arrivals, and no mammalian populations have established themselves other than bats, voles, and some mouse and rat infestations closely associated with the human habitations. Snakes are occasionally sighted; it is not known whether they arrived on their own, or were carried in as stowaways with loads of cargo.