|
|
|
||||
|
||||||
|
|
|
|
|
|
|
|
|
|
|
|
|
||
|
||||||
 |
||||||||||||||||||||||||||||||||||||||||||||
|
What is Happening?Trumpeter Swans (Cygnus buccinator) were once distributed across North America. By 1933, only 66 Trumpeters could be located in the US. The Canadian population was limited to only a few birds found near Grande Prairie, Alberta and on the British Columbia coast. They have since made a remarkable recovery. In 2000, the continental population was estimated at 23,647 individuals. This recovery is especially notable for the Trumpeter Swans of the Pacific Coast, the largest of 3 native swan populations recognized in North America. The Pacific Coast population comprises over 70% of all Trumpeter Swans (not including Tundra Swans) on the continent. Counts of this population on its breeding/summer range located mainly in the interior of Alaska show an increase from just 2,847 in 1968 to 17,551 swans (adults and juveniles) by the summer of 2000. An increase of more than 510% or 6.0% per year. A large portion (nearly 40% in 2000) of the Pacific Coast Trumpeter Swan population winters along south coastal BC and particularly on Vancouver Island. The trend in increasing population numbers on the breeding grounds is also reflected in swans wintering in BC. Mid-winter aerial surveys in south coastal BC (Vancouver Island and Lower Fraser River) by Environment Canada's Canadian Wildlife Service recorded a 615% increase in Trumpeter Swans between 1970 and 2001 (or 7.2% per year). The wintering population increased from only 947 swans in 1970 to 6,775 adult and juvenile swans in 2001. The 2001 survey showed a slight decrease (4.7%) in swans numbers from the 1998 high of 7,111.
Source: Pacific Coast data are from D. Caithamer (1996 and 2001) of the US Fish & Wildlife Service and the data refer to late summer counts on Trumpeter Swan breeding grounds. South Coastal BC winter data are from aerial surveys (A. Breault, Environment Canada, Canadian Wildlife Service, Delta, BC, 1999 and 2002). Fraser River delta winter data (collected annually since 1987) are also from aerial surveys (S. Boyd, Environment Canada, Canadian Wildlife Service, Delta, BC, 2002). Note: winter surveys were taken mid-winter (for example, the 1998 data refers to counts conducted in the 1998-99 winter). South Coastal BC winter totals include the Fraser River delta counts only after 1988. A similar trend in increasing wintering swans has been observed in this region since 1980 by the National Audubon Society Christmas Bird Count. Their 2001 count was 3,761 Trumpeter Swans, lower than their 2000 count of 4,145 but still showing an increase of 110% above the 1980-2000 long-term average (Breault 2002). As the wintering population of swans increased from 1968 so did its distribution within south coastal BC. The early swan surveys of the 70s and 80s did not include the Lower Fraser River area as swan numbers there were too low. However by the mid-80s (1987), their numbers and distribution had increased so they were counted in the annual CWS Lesser Snow Goose mid-winter Fraser River delta aerial survey. Over the next 12 years, this survey documented a 200% increase in swans wintering in the delta. By the winter of 1988, both the Fraser delta and the Lower Fraser River area were included in the south coastal BC Trumpeter Swan winter survey. At the same time Trumpeter Swans expanded their wintering range on Vancouver Island and the Lower Fraser River, swans on the east coast of Vancouver Island became more concentrated. In particular, 2,000-3,000 swans or 50% of the Island population, now gather in the Courtenay - Comox Valley area for most of the winter. Changes in the abundance and distribution of Trumpeter Swans in South Coastal BC in the winters of 1970-71 through 2001-02.
Why is it Happening?Following the Migratory Bird Convention of 1916, conservation efforts to help the Trumpeter Swan were legislated. Alaskan populations began to rebound and expand their breeding range. Efforts by both Canadian and American authorities to protect the species and its habitat, along with reintroduction to some areas from which it had been extirpated, soon had positive effects, and the population began to recover. Recruitment of young (cygnets) in the population has averaged 26% per year on the breeding grounds since 1968. On the Pacific Coast, wintering Trumpeter Swans found new food sources. In addition to coastal marshes, they started feeding on harvested vegetable fields, pastures and cover crops. These agricultural lands are concentrated on the east coast of Vancouver Island and the Lower Fraser River estuary. A combination of the swans no longer being hunted and having access to a rich and reliable food supply during the winter months resulted in the Pacific Coast population increasing to its present level. Why is it Significant?In April 1996, the Committee on the Status of Endangered Wildlife in Canada (COSEWIC) re-examined the status of the Trumpeter Swan. It was de-listed from a vunerable species to a species not at risk since its North American population was continuing to increase and approaching 20,000 birds. It had been designated by COSEWIC as a species of special concern in April 1978 and listed as vunerable in 1990. In British Columbia, the Ministry of Sustainable Resource Management has retained this species on their blue-list, species of special concern, as threats to winter habitat availability and quality are present and it is sensitive to disturbance and environmental contamination on the wintering and breeding grounds. Although the recovery of the Trumpeter Swan is a great success story for wildlife conservation, the increased number of birds wintering in southern BC is putting pressure on the agricultural lands they have come to depend on. In recent years, swans have taken advantage of the food provided on farmland. Since each swan can eat up to 1.2 kilos of grass per day (R. McKelvey, CWS, pers. comm., Oct. 1999), their foraging habits might translate into substantial forage losses to the farmer. Traditionally, swans would have foraged on intertidal and interior wetland plants.
Trumpeter Swans have also helped generate socio-economic spin-offs in the form of community self-identification and visitors' commerce. Past annual Trumpeter Swan Festivals, organized by the Comox Valley Naturalists, promoted better understanding of wildlife in the context of soil-based agriculture. Trumpeter Swans attract wildlife enthusiasts and photographers who visit the valley to view the birds and in turn generate revenue for local merchants. What is Being Done?Legislation protecting the swans was first enacted under the Migratory Bird Convention of 1916. This Convention controlled hunting and other human uses of birds, including Trumpeter Swans. Other acts expanded the protection of this species, and a continent-wide plan, the North American Management Plan for Trumpeter Swans, was adopted in 1984. In addition to legal protection, reintroduction, feeding programs and land acquisitions helped reestablish viable swan populations throughout Western North America. In BC, the Comox Valley Waterfowl Management Project and the Fraser River delta Greenfields project are two projects that attempt to address the concerns of both wildlife and agriculture. The Comox Valley Waterfowl Management Project, funded by Environment Canada and administered by Ducks Unlimited Canada (DUC), provides seed to farmers in the Comox Valley for winter cover crops. The cover crops serve to lure Trumpeter Swans away from perennial grass fields. The project also provides a hazing program consisting of dogs, noisemakers and visual deterrents to frighten swans away from protected fields. In the Fraser River delta, the Greenfields project is partially funded by Environment Canada and administered by the Delta Farmland and Wildlife Trust. This project also provides funding to local farmers to plant winter cover crops. These crops not only act as lures to swans and other grazing waterfowl, but they serve to protect soil from erosion and enrich the organic content of soils for the farmers. In 1998, the 78 hectare (ha) Farquharson Farm in the Comox Valley was purchased through the Pacific Estuary Conservation Program (the land acquisition arm of the Pacific Coast Joint Venture in BC). The Program is a partnership of government and non-government agencies including Environment Canada, Fisheries and Oceans Canada, BC Ministry of Environment, Lands and Parks, Ducks Unlimited Canada, Wildlife Habitat Canada, Habitat Conservation Trust Fund and The Nature Trust of BC. The farm is adjacent to the Courtenay River estuary in the Comox Valley. It represents important Trumpeter Swan habitat, used by 300-400 swans daily during the winter (Trumpetings, 1998). The farm is being managed as a working farm. It will not only provide habitat for swans, but will also help to fund the Comox Valley Waterfowl Management Project. By working together with the agricultural community Environment Canada supports the conservation of some of the most important habitat around, farmland. CWS and other agencies such as Ducks Unlimited Canada are continuing to develop partnerships with landowners, local organizations and community groups to meet the needs of the farming community, the general public and the Trumpeter Swans. CWS will continue to monitor both breeding and wintering populations of Trumpeter Swans. The survey of the breeding population will continue to be conducted at 5-year intervals in the northeast section of the province while the wintering population in southwest BC will continue to be assessed every 3 years. The portion of the wintering population found on the Fraser River delta area will continue to be monitored annually. Whenever possible, the monitoring will involve photo counts of flocks, a method that provides accurate and precise estimation of the population size and of the recruitment rate. As part of this monitoring program CWS in the summer of 2000 counted 470 Trumpeter Swans of the Rocky Mountain Population (RMP) in northeastern BC. This represented 13% of RMP breeding population and showed an increase of 40% over the 1995 counts (Breault 2002). As well in northern BC a February survey in 2001 revealed the presence of approximately 1151 swans (about 18% juveniles) wintering near Prince George (Breault 2002). In addition to addressing habitat and agricultural issues, CWS monitors other factors affecting Trumpeter Swans, such as lead poisoning. Lead poisoning from ingestion of lead shot is a primary cause of death among Trumpeter Swans wintering on the southern coast of BC. Between 1976 and 1994, 47% (87 of 186) of Trumpeter Swans found either dead or sick in BC were diagnosed as lead poisoned (Wilson et al. 1998). In 1990, there was restricted use of lead shot in selected waterfowl hunting areas in southern coastal BC, including important swan wintering areas. A province-wide ban on use of lead shot for waterfowl hunting was implemented in 1995, and broadened to a national ban in 1997. However, mortality by lead poisoning in Trumpeter Swans continues to be a problem. Over the past four winters (1999 to 2003) more than 850 swans are suspected to have been poisoned by ingestion of lead shot in the Sumas Prairie area south of Abbotsford BC and neighbouring Whatcom County in Washington State. A major international project is under way to investigate this problem and to find the source(s) of lead shot. Participants include CWS and 13 other agencies and non-governmental organizations on both sides of the border.
For more information contact: Andre.Breault@ec.gc.ca and Sean.Boyd@ec.gc.ca Check the following sites for additional information on this indicator:
The following Web sites are not under the control of Environment Canada (EC) and they are provided solely for the convenience of users. Environment Canada is not responsible for the accuracy, currency or the reliability of the content. Environment Canada does not offer any guarantee in that regard and is not responsible for the information found through these links, nor does it endorse the sites and their content. Users should be aware that information offered by non Government of Canada sites that are not subject to the Official Languages Act, and to which Environment Canada links, may be available only in the language(s) used by the sites in question.
For references used in this indicator click here. |
|||||||||||||||||||||||||||||||||||||||||||
|
|
|
||||||||||||||||||||||||||||||||||||||||||
|
|
|||
|
|
||||
|
| Français
| Contact Us
| Help
| Search
| Canada Site
|
||||
On the east coast of Vancouver Island,
for instance, the impact of swans on livestock operations may result in
losses to farmers. In the Comox Valley, swans feed on dairy pastures and
this has resulted in damage to perennial grass crops being reported.
