Thursday, July 25, 2019

Swans on the Assabet River

Mute swan at rest, Assabet River, Stow, MA
Mute swans reside on the Assabet River, either as solitary birds or nesting pairs. These swans can occasionally be spotted from the Ice House Landing dock, but will always be seen when kayaking or canoeing upriver into Stow.

Swans are long-lived, and return to the same nesting place. Of the 5–8 eggs laid each spring perhaps 1–3 cygnets will reach maturity. Unlike Canada geese, parent mute swans do not allow the yearlings to return to the same area the next spring, so in any summer the local populations are either solitary birds or parenting pairs with the new cygnets. Hatchlings start off gray in color, not turning white until their second year. They can paddle about within days after hatching, but need 60 days to mature enough to fly.

In flight, swans make Canada geese look small and slow. Low-flying geese meander about at 20–30 miles per hour. Higher-flying geese, the ones actually migrating, are at flock speed of 35–45 mph. In contrast, once swans have powered up they are doing 50 mph. At more than twice the weight of a ten-pound goose and with a wingspan of almost eight feet, this is one impressive bird. The wings of mute swans in flight make a distinctive whooshing sound that on still mornings can be heard more than half a mile away.

In the U.S., mute swans do not migrate southward. Come winter, they shift to the ocean shore, where they may congregate in groups. Come spring, the existing pairs head back to their nesting waters, while the three year-olds will be pairing up for the first time before seeking nesting waters of their own. Lifespan in the wild can by 10–15 years. Swans will often stay in mated pairs for many years, but if one dies, the other will take a new mate. And they are not actually “mute,” as they can hiss, snort, yip and so on; it’s just by comparison their not being as loud as North America’s native trumpeter swans.

The business end of a mute swan (internet download)
Boaters of any type should not approach mute swans during nesting and cygnet-raising seasons. These birds are SERIOUSLY territorial. On land or on the water, males act to prevent any animal or human from getting near the nest. That yard-long neck may look like a cute sock-puppet, but it is wielded more like a poking, pinching hand, combined with hard blows from the forward edge of the wings. Swans have been known to attack dogs and children. Swans have been known to attack swimmers, canoes and kayaks. Swans can sink jet skis, flip ATVs and down ultralight aircraft. OK, maybe not those last three, but really, leave nesting swans alone. There is one reported instance of a man (not wearing a life jacket) knocked out of his kayak and drowned by a nest-protecting swan.

Mute swans are not native to North America, and in fact are viewed as an invasive and destructive species because of their voracious appetite for aquatic vegetation and harassment of other water bird species. The first introductions were in New York state prior to 1900. Escaped swans initially established feral populations along the Hudson River, Long Island Sound and Chesapeake Bay, but have since spread to the Mid-west and North-west regions, numbering in the tens of thousands and increasing by more than 10 percent a year. A single mute swan can consume four to eight pounds of plants a day. Continuous feeding by a flock of mute swans can destroy an entire wetland ecosystem.

Various state programs attempt to control local populations. Some states along the Atlantic coast have hired professional hunters. Another control method is to coat the eggs with corn oil, which will prevent hatching (removing the eggs triggers the female to lay replacement eggs).  

“But they are really pretty.” Yes, they are. Mute swans were imported from England starting in the late 1800s as living ornaments for private and public garden ponds. The Swan Boats in Boston Public Garden are modeled on mute swans, right down to the orange beak and half-raised wings. Swimming, mute swans hold their heads curved down a bit rather than looking straight forward. Mated pairs oft face each other in the water, so in silhouette their necks and heads make a heart shape. The website takes the position that mute swans are in fact native to North America, and thus deserve the same protections as native birds.

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