Coast Microseris (Microseris bigelovii) COSEWIC assessment and status report: chapter 2

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COSEWIC Executive Summary

Species information

Coast microseris (Microseris bigelovii) is a small stemless herb of the aster family with narrow, entire to deeply lobed basal leaves and a leafless flowering stalk bearing a single yellow flower head. Its fruits (achenes) are crowned by five distinctively shaped scales, each terminating in a long, hair-like bristle.

Distribution

The species ranges from Vancouver Island south along the coast to California. In Canada, M. bigelovii is restricted to southeast Vancouver Island and the adjacent Gulf Islands. The nearest extant population outside Canada occurs in Yachats, Oregon, about 450 kilometres to the south.

Habitat

In Canada, coast microseris occurs on open rock bluffs and in rock-bound vernal seeps within 100 metres of the ocean. The sites are moist in autumn, winter and spring but dry during the summer.

Biology

The species is a self-pollinated annual that flowers and fruits in late spring. Seeds appear to have no dormancy mechanisms. Canadian populations possess a number of genetic traits that suggest they are derived from a single founder.

Population sizes and trends

Coast microseris is found in only six sites in Canada. All six sites are small with populations varying in size from 100 to 2,500 plants per site for an aggregate total of 5,500 to 6,500 individuals. It has become extirpated from at least four, and perhaps as many as six, historic locations in Canada.

Limiting factors and threats

Habitat loss and degradation presents the primary threat in Canada. An estimated 95% of the potential habitat has been lost over the past century due to urban and industrial development along with fire suppression and invasion by exotic herbs and shrubs. The species is restricted to the sub-Mediterranean climate of southeast Vancouver Island, and even there it only occurs in the ameliorated climate of shoreline locales, which experience fewer frosts and receive more moisture in the form of fog.

Special significance of the species

The Canadian populations are of scientific interest because they are highly disjunct from the species’ main range, and because they are genetically distinct from plants in the main range of the species.

Existing protection or other status designations

Coast microseris is not protected by any endangered species legislation. Only one population occurs in a protected area. It has a global rank of G4 – apparently secure.

COSEWIC History

The Committee on the Status of Endangered Wildlife in Canada (COSEWIC) was created in 1977 as a result of a recommendation at the Federal-Provincial Wildlife Conference held in 1976. It arose from the need for a single, official, scientifically sound, national listing of wildlife species at risk. In 1978, COSEWIC designated its first species and produced its first list of Canadian species at risk. Species designated at meetings of the full committee are added to the list. On June 5^th 2003, the Species at Risk Act (SARA) was proclaimed. SARA establishes COSEWIC as an advisory body ensuring that species will continue to be assessed under a rigorous and independent scientific process.

COSEWIC Mandate

The Committee on the Status of Endangered Wildlife in Canada (COSEWIC) assesses the national status of wild species, subspecies, varieties, or other designatable units that are considered to be at risk in Canada. Designations are made on native species for the following taxonomic groups: mammals, birds, reptiles, amphibians, fishes, arthropods, molluscs, vascular plants, mosses, and lichens.

COSEWIC Membership

COSEWIC comprises members from each provincial and territorial government wildlife agency, four federal entities (Canadian Wildlife Service, Parks Canada Agency, Department of Fisheries and Oceans, and the Federal Biodiversity Information Partnership, chaired by the Canadian Museum of Nature), three non-government science members and the co-chairs of the species specialist subcommittees and the Aboriginal Traditional Knowledge subcommittee. The Committee meets to consider status reports on candidate species.

Definitions (2006)

Wildlife Species

A species, subspecies, variety, or geographically or genetically distinct population of animal, plant or other organism, other than a bacterium or virus, that is wild by nature and is either native to Canada or has extended its range into Canada without human intervention and has been present in Canada for at least 50 years.

Extinct (X)

A wildlife species that no longer exists.

Extirpated (XT)

A wildlife species no longer existing in the wild in Canada, but occurring elsewhere.

Endangered (E)

A wildlife species facing imminent extirpation or extinction.

Threatened (T)

A wildlife species likely to become endangered if limiting factors are not reversed.

Special Concern (SC)^Footnotea

A wildlife species that may become a threatened or an endangered species because of a combination of biological characteristics and identified threats.

Not at Risk (NAR)^Footnoteb

A wildlife species that has been evaluated and found to be not at risk of extinction given the current circumstances.

Data Deficient (DD)^Footnotec

A category that applies when the available information is insufficient (a) to resolve a species’ eligibility for assessment or (b) to permit an assessment of the species’ risk of extinction.