Tweeters,

The willingness to want to control Mute Swans is probably due to their documented adverse impacts where they have naturalized around Chesapeake Bay: This (below) I gleaned from the internet regarding their population ecology and ecological concerns of the Mute Swan. These concerns probably prompted some "jerk" in our state to "decided that Mute Swans are such a terrible invasive species that they have have to be killed" before their populations grow the point of affecting wintering waterfowl in the Puget Sound area. I guess we can pinion them and distribute to cemetery ponds across the region rather than killing them. Not sure what the answer is...but control is probably necessary. We certainly don't want them to affect eelgrass abundance which would impact wintering Brant populations.

Population Ecology
Atlantic flyway. The mean annual rate of population growth for mute swans in Maryland was 36% from 1962 to 1979. From 1986 to 1999, the mute swan numbers in Maryland increased from 264 to 3,955, an increase of 1,389%. The 1999 estimate of total mute swans in the Atlantic flyway was 12,600 birds. The growth rate for mute swans in the Chesapeake Bay since 1986 has been 1,271%. A nest survey in the Patuxent River in 2000 revealed five nests; a survey conducted in 2001 revealed 40 nests. Population modeling of Maryland's mute swan population indicates that it could include over 20,000 birds by 2010 if growth is unchecked (Harvey 2000). From 1989 to 1999, according to the Atlantic Flyway Survey, Massachusettes' mute swan population grew 68%, Rhode Island's 79%, New Jersey's 159%, Pennsylvania's 78% and Virginia's 713%.

Mute swans are year-round residents in the Chesapeake Bay and are not true migrants in any part of their range in North America. While occurring throughout the Bay, they are most concentrated from Rock Hall in Kent County south to Hoopers Island in Dorchester County. Until they are old enough to nest, and during the winter months, mute swans spend most of their time in large flocks composed of juvenile, sub-adult swans. Flocks of 600 to 1,000 birds have been recorded in the Chesapeake Bay. Breeding pairs remain on territories most of the year.

Mortality after mute swans reach breeding age is low. Causes of mortality can include disease, severe winter weather, lead toxicosis, collision with high tension wires or other man-made structures and incidental shooting in Virginia, Pennsylvania and Delaware where they are unprotected by state law, . Once they reach breeding age, about 85% survive from one breeding season to the next. Average life expectancy is 11 years and the maximum is 21 years (Ciaranca et al. 1997).

Ecological Concerns
Of primary concern to Chesapeake Bay ecologists is the rate of mute swan population growth in the Chesapeake Bay, its presence year-round and its preference for feeding on submerged aquatic vegetation (SAV). Certain SAV species, such as wild celery (Vallisneria americana), are especially vulnerable because their reproduction and growth are timed to avoid the heavy grazing of migratory waterfowl. Wild celery requires its reproduction process to be protected from grazing while its seeds are maturing. If consumed before seeds are mature, it will not reproduce and will waste living energy in this process. A large, resident mute swan population feeding on SAV all year could jeopardize the ability of SAV to recover from winter waterfowl grazing and make it less available for waterfowl the following winter. Declines in SAV abundance appear to correlate with declines in local black duck (Anas rubripes) abundance (Krementz 1991). Population trends suggest that habitat degradation in Chesapeake Bay, especially loss of SAV, may be the principal cause of the decline of the Bay's canvasback (Aythya valisineria) population (Haramis 1991). Furthermore, the loss of SAV over the past several decades has prompted the near abandonment of Bay waters by redheads (Aythya americana), leaving only a remnant population today (Haramis 1991).

In closed waterways in Europe, mute swans have been documented as removing entire species of SAV (Gillham 1956, Jennings et al. 1961, Mathaisson 1973, Chairman 1977, Neirheus and Van Ireland 1978, Scott and Birkhead 1983). In a recent Rhode Island exclosure study, for example, findings indicated that mute swans overgraze SAV when water is shallow (0.5 m), reducing SAV biomass by 92 to 95% (Allin and Husband 2000). The Chesapeake 2000 Agreement includes a commitment to restoring 114,000 acres of SAV; however, restoration efforts, particularly in the mid-Bay where SAV decline is most severe, are frequently obstructed by feeding mute swans.

Mute swans compete with native, wintering tundra swans (Cygnus columbianus) for shelter and food to a lesser extent than shelter. Tundra swans lose mass during the winter and depart from the wintering grounds at their lowest mass (Bortner 1985, Limpert et al. 1987). Harassment by mute swans may cause tundra swans to lose mass more rapidly, which could affect subsequent reproduction. Inter-specific aggression during nesting season has been documented in the Chesapeake Bay between Canada geese and mallard and black ducks.

In the early 1990s, a molting flock of between 600 to 1,000 mute swans utilized a beach area, Barren Island (off of Blackwater National Wildlife Refuge), as a loafing site. This same site was the last remaining nesting site for black skimmers (Rynchops niger) and the last natural nesting site for least terns (Sterna antilarum) in Maryland. The mute swan activity crushed eggs and young of birds nesting in the beach colony, which led to the black skimmers and least terns abandoning this area for three nesting seasons (Maryland DNR files).



Jeff Kozma

Yakima (j c r underscore 5105 at charter dot net)

----- Original Message -----
From: Guttman,Burt
To: Tony ; tweeters at u.washington.edu
Sent: Friday, January 07, 2011 5:33 PM
Subject: RE: [Tweeters] Mute Swans an Invasive Species ??


I was quite alarmed by this item in the Olympian. Thanks, Tony, for the link to the law. The long-term question for me is, "What jerk decided that Mute Swans are such a terrible invasive species that they have have to be killed, and how can we get some of our legislators to change the law?" The short-term question is whether we birders and other nature enthusiasts can exert some pressure on the officials with shotguns who are likely to be out gunning for these beautiful creatures? It's probably the same pair that comes over here to Long Lake occasionally, and the thought of anyone killing them makes me sick. Ideas, anyone? Does anyone have personal connections to people who might be able to stop this now?

Burt Guttman
The Evergreen State College
Olympia, WA 98505 guttmanb at evergreen.edu
Home: 7334 Holmes Island Road S. E., Olympia, 98503


------------------------------------------------------------------------------
From: tweeters-bounces at mailman2.u.washington.edu on behalf of Tony
Sent: Thu 1/6/2011 3:08 PM
To: tweeters at u.washington.edu
Subject: [Tweeters] Mute Swans an Invasive Species ??


This is interesting and wonder if there is some other approach short of killing them??

Hicks Lake mute swans will be killed


http://www.theolympian.com/2011/01/06/1496380/hicks-lake-mute-swans-will-be.html


The law:


http://apps.leg.wa.gov/WAC/default.aspx?cite=232-12-017


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