[mou] Info on Mute Swan

[Jim Williams]

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
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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