Notes on Beaver History#

Ancestral members of the beaver family, Castoridae (in the Order: Rodentia) date back more than 20 million years, globally.

From fossil evidence, around 30 genera have been identified as having belonged to this family, mostly in Eurasia.
One notable North American ancestor was the bear-sized Giant Beaver, Casteroides, which died out about 10,000 years ago. These pre-historic mega-fauna averaged over six feet long and 3 feet tall, and weighed over 200 pounds. Their range was mainly in the Midwest. No reports were found (for this note) of fossil evidence in Massachusetts, but some Native American legends suggest that the Giant Beaver might have ranged into the central part of our state.

The family Castoridae is now represented by just one genus, Castor, containing two species: the North American beaver (Castor canadensis), and the closely related Eurasian beaver (Castor fiber).

Fossil evidence suggests that the beaver reached North America over the Ice Age land bridge from Asia.
Castor canadensis populated southern New England about 12,000 years ago, following retreat of the Laurentian ice sheet (see Kaye, 1962).
The post-glacial beaver intrusion probably led to the damming of nearly every feeder stream and small river in the region, creating a vast network of pond and wetland ecosystems.
Prior to European colonization, beavers ranged from northern Mexico to the Arctic tundra, excluding only the driest deserts and the Florida panhandle (where juicy beavers would quickly fall prey to alligators). At that time, the total beaver population may have numbered in the hundreds of millions.

Forest products, fish and furs – mainly from beavers – were the principal exports to Europe during the early colonial period.

By the early 17th century, when the British began colonizing North America, Castor fiber had already been extirpated from most of Europe. Once abundant supplies of beaver pelts became available in the New World, beaver hats became highly fashionable in Europe and remained so until the mid 19th century when silk became more widely available.
Beaver fur consists of a covering of long “guard hair” above a dense mat of “under wool.” To make beaver hats, hatters sheared the pelt, separated the hair and wool, and then boiled and pounded the soft inner wool to produce a warm, luxurious, water-proof (!!) and long-lasting felt – often in combination with rabbit fur and wool. Beaver pelts were especially useful for felting due to the thickness of the under wool, and the fact that under-wool hairs have microscopic barbs that mesh together like an early form of Velcro.

The high demand for beaver pelts led to the total elimination of beavers from Massachusetts, and most of New England.

To expand the supply of beaver pelts, early European traders and colonists recruited local Indians to trap beavers far and wide, exchanging pelts for trade goods such as knives, axes, metal pots, cloth, and glass beads (and alcohol, illicitly).
According to Salisbury (1982, p. 201):
“If we look closely at the pattern of trade in Massachusetts Bay in the early 1630s, we find that the Pawtucket and Massachusetts had run out of furs to trade… The English merchant backers of the Massachusetts Bay Company, like their Plymouth counterparts, looked to the [fur] trade as the principal source of returns on their investment. Yet within two or three years they discovered that the fur-bearing animal population near the coast had been depleted”
Similarly, Cronin (1983, p. 99) states that beavers had been eliminated from coastal regions of Massachusetts by 1640.
Around 80,000 beaver pelts per year were being exported to England and the Netherlands by the mid 1600s. (Goldfarb, p. 50).
The beaver was gone from the entire state of Massachusetts by the early 1700s (Muller-Schwarze, 2003, p170).
- Henry David Thoreau never saw a beaver in Massachusetts! Nor a deer. In an 1855 speech he lamented: “I cannot but feel as if I lived in a tamed, and, as it were, emasculated country.”
Elimination of the beaver population led to a wholesale loss of pond and wetland habitats. This dramatic change in local ecology was reinforced by loss of forest cover for timber, firewood, and farmland, and widespread draining of remaining wetlands to create more farm fields.

The beaver was “re-established” in the state in the early 1930s (Jackson and Decker, 2004).

By some accounts the “re-establishment” involved natural expansion of a growing population from the Adirondacks; other sources mention deliberate re-stocking in western Massachusetts.
From that seminal population in western Massachusetts, beavers spread gradually across the state thanks to a combination of natural population growth and an “active restoration campaign” (Jackson and Decker, 2004) for protecting wetlands.

Beavers finally spread their range to the north shore and were re-established in the Sanctuary around 1990 – after an absence of 350 years!

One spot along the North Esker trail features faint signs of an old wagon wheel track coming across Hassocky Meadow from Averill Island. This is evidence that the meadow had been dry enough for horse carts to pass through back in the days when the Averill family was logging the island to produce wooden furniture nearby.
Old-timers in Topsfield recall walking across Hassocky Meadow when it was a seasonally dry meadow, before the return of the beaver. And older maps of the Sanctuary trail system show portions of the Mile Brook Trail and the Rockery loop that are now under water, due to the return of beavers.

Additional Reading #

Cronin, William (1983), Changes in the Land: Indians, Colonists, and the Ecology of New England. New York: Hill and Wang.

Goldfarb, Ben (2018), Eager: The Surprising, Secret Life of Beavers and Why They Matter. White River Junction: Chelsea Green Publishing.

Kaye, Clifford A. (1962), “Early Postglacial Beavers in Southern New England,” Science, vol. 138 issue 3543, 906-907.

Jackson, Scott and Thomas Decker (2004), Beavers in Massachusetts. University of Massachusetts Extension and Massachusetts Division of Fisheries and Wildlife. (Revised 6/2004)

Muller-Schwarze, Dietland (2003), The Beaver: Its Life and Impact. Ithaca: Comstock (Cornell University Press).

Salisbury, Neal (1982), Manitou and Providence: Indians, Europeans, and the Making of New England, 1500-1643. New York: Oxford University Press.

Note prepared by Bruce Bolnick, January 2019, revised February 2020.