Mute swans are large, impressive birds that many people are delighted to see in public water bodies and in New York State Parks.
However, many people are unaware that mute swans are a non-native species which can create negative impacts in our parks. Mute swans (Cygnus olor) were introduced to the U.S. from Europe during the late 1800s and early 1900s as decorative accessories to zoos, parks, and private estates.
In New York State, Mute swans were particularly popular on private estates on Long Island and in the Hudson Valley. Many of these pet swans escaped from captivity or were intentionally released into the wild. Since their introduction, wild mute swans have successfully expanded their habitat to the extent that it is now a source of concern for natural resource managers
Environmental Impacts: What do we have against swans, anyway?
Mute swans are highly territorial and will aggressively defend their large territories against other birds—including native waterfowl. This hurts our native bird populations by limiting their access to feeding areas and potential nesting sites. Mute swans may also act aggressively towards humans who walk, swim, or boat too close to their nesting sites.
Besides being physically threatening, mute swans place a greater strain on the aquatic habitats where they feed. Their long necks reach a greater number of underwater plants than other birds’. Besides eating aquatic plants, mute swans tend to uproot much of the aquatic vegetation where they feed, which would otherwise provide food and shelter for native waterfowl species, fish and other organisms.
The tundra swan is one of two native swan species in New York State (the other is the trumpeter swan, see below). A graceful tundra swan is an incredible sight for bird lovers. The average tundra swan has wingspan stretching just over five feet. While the tundra swan is the smallest swan species observed in New York State, averaging more than 14 pounds, they are still larger than a Canada Goose. While Tundra Swans are similar in size and coloring to trumpeter swans, their voice is distinctly different. Listen for their clear hooting, which sounds like klooo or kwooo.
They typically feed on shellfish, aquatic plants, and occasionally grains. While tundra swans spend most of the breeding season in the Arctic, where nesting and hatching takes place, these strong birds migrate southwards annually and frequently rest, feed, and eat in New York State Parks.
Trumpeter swans are the largest of the North American waterfowl, weighing as average 23 pounds. Their call is a gentle nasal honk, lower in tone than the tundra swan. The trumpeter swan was almost rendered extinct by the high demand for swan feathers for use as quill pens throughout the 1600s-1800s. Trumpeter swans have successfully rebounded and they are relatively common in North America today, but they continue to be rare in New York. Providing and protecting suitable nesting habitat could be key to helping New York trumpeter swan populations grow.
In a few places where the mute swan population is particularly high, State Parks is working with the state Department of Environmental Conservation and Wildlife Services to manage population growth and protect aquatic species and habitats in State Parks. In order to do so most effectively, State Parks is utilizing an integrated, multi-pronged approach:
- Public Education: Many people value the presence of mute swans, but are often unaware that they are an invasive species which can negatively impact the ecology of parks. Educating the public is key to managing wildlife and promoting ecosystem health.
- No Feeding Policy: All State Parks have a strict no-feeding policy for all wildlife. Feeding wildlife can be harmful to them and set up dangerous situations for people.
- Habitat modification: Like Canada geese, mute swans seek out grassy lawns and open areas adjacent to water bodies. By allowing shoreline vegetation to grow taller, or by installing fencing, we can make it more difficult for mute swans to travel from water to land — therefore making park facilities less attractive habitats.
- Nest and Egg Treatment: Oil blocks the exchange of oxygen through the shell and prevents young birds from hatching. Following the guidelines set by the Humane Society, parks’ staff always perform a float test before treating eggs. If an egg floats, it means that an air sac has formed and a chick has begun developing. By oiling swan eggs early in the season before chicks have begun developing, State Parks staff and partners are able to prevent halt swan reproduction. This process helps reduce the local population over time. A permit is required to disturb any swan nest or eggs on park or private property.
- Population Control: In order to protect endangered or threatened plants as well as significant natural communities in or near State Parks boundaries, lethal methods may be used to manage mute swan populations. As in all cases of animal control, lethal measures are only considered as a last resort.