Birds have been called “bellwethers of watershed health.” Because they respond to basic changes in landscape and habitat conditions, birds can be excellent indicators of watershed health.
Roger Tory Peterson, an American naturalist who published many books about birds and garnered multiple awards in his field, once said, “Birds are an ecological litmus paper. Because of their rapid metabolism and wide geographic range, they reflect changes in the environment quickly, and they warn us of things out of balance, sending out signals whenever there is deterioration in the ecosystem.”
GLA’s Watershed Biologist Rob Karner, a former ornithology instructor, helps the GLA monitor our bird variety, patterns, and health as a potential leading indicator of overall watershed health. The robust variety and health of our year-round resident birds and migratory birds point to a healthy watershed, and we want to introduce you to some of them.
This is a trumpeter swan, which you’ll often see around our watershed on open water. In terms of average mass, it is the heaviest flying bird in the world.
Like other swans, trumpeter swans often mate for life, and both parents participate in raising their young, but primarily, the female incubates the eggs. Most pair bonds are formed when swans are five to seven years old. The average lifespan of trumpeter swans is 20-30 years.
The breeding habitat of trumpeter swans includes large and shallow ponds, undisturbed lakes, pristine wetlands, wide and slow rivers, and marshes. These swans feed while swimming, sometimes up-ending or dabbling in reaching submerged food. The diet is almost entirely aquatic plants and occasionally insects. They will eat both the leaves and stems of submerged and emergent vegetation. They will also dig into muddy substrates underwater to extract roots and tubers. In winter, they may also eat grasses and grains in fields.
The trumpeter swan has not always been in our watershed. More than 100 years ago, European settlers brought the elegant mute swan to North America, but the beautiful birds also proved to be aggressive and invasive. By 1855, due to pressures from hunting, loss of habitat, and competition from mute swans, the native trumpeter swans became extinct in Michigan. Fewer than 70 trumpeter swans were known to exist in the entire lower 48 by 1933.
By the end of the 20th century, the mute swan was a fixture of our watershed. With the invasive mute swan population rapidly rising, the Michigan Department of Natural Resources put a plan in place to slowly reduce their population. In 2006, Sleeping Bear Dunes National Lakeshore, in partnership with the Little River Band of Ottawa Indians, released eight immature trumpeter swans in a wetland within the park in hopes of reestablishing a breeding population. Today, these trumpeter swans and their descendants can be seen in and around the watershed and their population continues to grow, while the invasive mute swans are considered generally gone from our watershed.