Here is summary information regarding Mute Swans, taken from the web=20 site of the Chesapeake Bay Program Office: 410 Severn Avenue, Suite 109,=20 Annapolis, MD 21403 /=A0Tel: (800) YOUR-BAY / Fax: (410) 267-5777, URL: http://www.chesapeakebay.net/muteswan.htm=A0
Home > Animals and Plants > Invasive Species > Mute Swan =A0 Background The mute swan (Cygnus olar) was introduced to the Chesapeake Bay region=20= for its ornamental value but has had an increasingly disruptive effect=20= on the ecology of the Bay as well as on that of other areas as far=20 north as Maine and as far west as Michigan. The mute swan was first=20 introduced to North America in the 19th century in the Hudson River=20 Valley region of New York from Europe and Asia. Mute swans live=20 primarily in estuarine river habitats, with smaller numbers occurring=20 on inland lakes and ponds. Mature mute swans are larger than the Chesapeake Bay's native tundra=20 swans; they may become as heavy as 25 pounds versus16 pounds. They are=20= also very aggressive. Mute swan cobs (males) have been known to protect=20= up to a six-acre area surrounding their nests in ponds, lakes and=20 marshes. A mating pair of mute swans will return for many years to=20 their established territory, and often will remain throughout the year=20= near the Chesapeake Bay. The Problem There appears to be interspecific competition between mute swans and=20 our native tundra swan which winters in the Chesapeake Bay, but breeds=20= in Alaska and Canada. Mute swans have been observed exhibiting=20 aggression toward tundra swans, driving them from protected coves and=20 feeding areas. The mute swan may be responsible for recent declines in=20= tundra swans wintering in the Chesapeake Bay, but studies are needed. Mute swans are estimated to eat over 9,000,000 pounds of submerged=20 aquatic vegetation (SAV) each year. The loss of SAV, plus the damage to=20= the beds is limiting the recovery of SAV which provides food and=20 habitat for Bay organisms. Mute swans threaten biodiversity by=20 trampling eggs and chicks of nesting native waterbirds, such as the=20 threatened black skimmer and terns. The Solution The mute swan population in the Chesapeake Bay area has grown by over=20= 1,150 percent since 1986. Chesapeake Bay mute swan population has=20 soared in recent years; in 2002, 4,156 swans were counted - a=20 tremendous increase over the 264 recorded in 1986. While this=20 population may sound manageable, especially when compared with the=20 populations of other invasive species, the swan's aggressive=20 territorial behavior and destruction of SAV beds make even a small=20 population of these birds a potentially serious threat to the Bay's=20 sensitive ecosystem. Since the mid-1990s Maryland DNR and some Federal=20= agencies have attempted to control mute swan populations by addling=20 eggs to prevent further spread. Since the population has continued to=20 grow, Maryland has decided to remove birds in addition to addling eggs=20= in order to reduce the population. Mute swan control activities are=20 coupled with outreach activities to heighten public awareness of the=20 problems created by mute swans. Jim Williams Wayzata
