Altitude 0 - 200m
Description du site
The K'omoks IBA, along the east-central coast of Vancouver Island near the city of Courtenay, is an extensive network of marine waters, estuaries, backshore areas and associated lowland valley bottoms. Inland lowlands are a mixture of agricultural areas and forested land. Forests are predominately Coastal Douglas-fir and Western Hemlock while some dry Garry Oak/Douglas-fir forest occupies drier sites. An extensive estuary ecosystem extends from K'omoks Estuary through Baynes Sound to Deep Bay and Mapleguard Point, approximately 30 km to the southeast. Baynes Sound is a shallow coastal channel fringed by protected bays, open foreshore, tidal estuaries and inshore marshes. The shoreline includes wide expanses of mud and sand flats, low gradient deltas and sand and gravel beaches. This area is the most important intertidal area in B.C. for oyster and shellfish aquaculture. Further offshore, Lambert Channel and the marine waters surrounding Hornby Island have mostly rocky shores and rocky headlands, that provide extensive feeding and resting areas for waterbirds, especially during herring spawn in late-winter and early-spring.
The K'omoks IBA is an amalgamation of the former Comox Valley IBA, Baynes Sound IBA and Lambert Channel/Hornby Island Waters IBA. These three IBAs share common populations of waterbirds but were established as separate IBAs because they were nominated independently; follow the links to access the original site information.
This IBA is designated for four species at the global level: Trumpeter Swan, Harlequin Duck, Thayer's Gull, Glaucous-winged Gull; one species at the continental level: Mew Gull; and two species at the national level: Great Blue Heron and Peregrine Falcon. Continentally significant numbers of Waterbirds occur each year and, in some years, globally significant numbers have been recorded for Surf Scoter and Western Grebe and continentally significant numbers for White-winged Scoter and Red-necked Grebe.
The Comox Valley is notable for the numbers of Trumpeter Swan that over-winter there. Based on regular surveys, the numbers of swans increased to the late-1990s and have stabilized at an over-wintering (February) population of over 2,100 birds, with peak counts of over 2,900 birds. The swans arrive in late October and have mostly departed by early April. They feed on discarded vegetables or corn cobs, green forage between harvested corn, and seedlings of various winter cover crops, as well as native vegetation in the estuary.
Aggregations of Harlequin Duck gather at a few locations on the northeast side of Hornby Island during herring spawn. These aggregations can include 49-81% of the midwinter population of Harlequin Duck in the northern Strait of Georgia. An estimated 3,400-5,500 birds were present in 1996-2001. Aggregations occur in only a small fraction of the habitat area where spawn is available, indicating the importance of the site. During summer and early fall, the shores of Hornby Island are also a major roost site for moulting Harlequin Duck. Systematic surveys have not been conducted since 1996-2001, but regular shore-based counts indicate that the Harlequin Duck population appears to be stable (shore-based counts are lower than those obtained from a systematic survey).
Aggregations of 30,000-60,000 Waterbirds occur each year during herring spawn. About a third of those birds are waterfowl, including significant numbers of Surf Scoter and White-winged Scoter in some years, and about 60% are gulls, including significant numbers of Mew Gull, Thayer's Gull and Glaucous-winged Gull.
Historically, Western Grebe wintered here in globally significant numbers, with high counts ranging from 1345-4700 birds between 1978 and 1997. However, the numbers have declined steeply since then and only one count (2003) was close to the 1% global threshold. This significant decline has been noted throughout the Salish Sea (British Columbia and Washington); the reasons for the decline are not clear but may be related to a decrease in forage fish and a subsequent southerly shift in wintering areas.
Red-necked Grebe was recorded at continentally significant levels in early September 2007 and 2012. The Deep Bay area may be a significant fall moulting area for this species but more study is needed as there have been few comprehensive surveys at that time.
The IBA supports important numbers of three species determined to be Threatened or Special Concern by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC; wildlife species that have been assessed as at risk by COSEWIC may qualify for legal protection and recovery under Canada's Species at Risk Act). Great Blue Heron (fannini subspecies) (Special Concern, COSEWIC) has several colonies in the IBA (up to 100 individuals). Marbled Murrelet (Threatened, COSEWIC; and Endangered, the International Union for Conservation of Nature, IUCN) occurs regularly in the IBA most of the year (peak counts of at least 50-100 individuals). Peregrine Falcon (Special Concern, COSEWIC) winters regularly in the IBA and 1-2 pairs nest there.
Enjeux de conservation
The number of people living in the IBA has doubled over the past 20 years and is expected to continue to increase. Impacts associated with increased development, including discharges from sewage and suburban storm sewers, wetlands being filled in, and new housing developments and associated commercial/industrial areas reduces the amount, and degrades the quality, of habitat for Trumpeter Swan and other waterbirds. Loss of soil-based agriculture also reduces habitat available for swans. From 1992 to 2002, at least 5% of the sensitive ecosystems and over 29% of modified ecosystems such as older second growth forests and seasonally flooded agricultural fields were lost to other uses. Disturbance from increased recreational activities also poses a potential threat to bird populations using the area.
Many of the species using this IBA are dependent on herring spawn. Any activity that negatively impacts the herring spawn (e.g. reductions in water quality, foreshore development) could have significant impacts on the ability of this site to support a concentration of birds. The recent demand for expanded aquaculture development will need to continue to be evaluated carefully for its impact on birds.
There is limited legislated protection in place for the marine waters; the most significant is the marine extension to Helliwell Provincial Park. On the uplands, there is a National Wildlife Area and several Provincial and Regional Parks, mostly forested habitat. Several areas of upland habitat are owned or managed for wildlife conservation, especially for Trumpeter Swan and waterfowl, by Ducks Unlimited Canada and The Nature Trust of British Columbia. As well, the Comox Valley Waterfowl Management Project (Ducks Unlimited Canada and Canadian Wildlife Service) is a cooperative farm and wildlife extension program established to maintain wintering waterfowl populations in harmony with successful farming.
An IBA Conservation Plan was written for part of the IBA (2001), but needs to be updated. Specific conservation strategies will vary across the IBA to reflect differences in habitats and threats. The IBA is recognised in the Comox Valley Conservation Strategy (Nature Without Borders) and in some Official Community Plans.
Within the IBA, members of the Comox Valley Naturalists Society have been conducting standardised bird monitoring for five decades: Christmas Bird Counts since 1961, Spring Bird Counts since 1976, weekly Trumpeter Swan Counts since 1990, as well as other bird counts. Volunteers also have been collecting monthly counts for the British Columbia Coastal Waterbird Survey since 1999 and monthly surveys for the British Columbia Beached Bird Survey since 2002.
Menaces Potencielles ou Existantes
Status de Protection