Ermine Haidarum Subspecies,Mustela Erminea Haidarum
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COSEWIC Assessment and Status Report on the Ermine haidarum subspecies Mustela erminea haidarum in Canada THREATENED 2015 COSEWIC status reports are working documents used in assigning the status of wildlife species suspected of being at risk. This report may be cited as follows: COSEWIC. 2015. COSEWIC assessment and status report on the Ermine haidarum subspecies Mustela erminea haidarum in Canada. Committee on the Status of Endangered Wildlife in Canada. Ottawa. xi + 38 pp. (www.registrelep-sararegistry.gc.ca/default_e.cfm). Previous report(s): COSEWIC. 2001. COSEWIC assessment and update status report on the Ermine haidarim subspecies Mustela erminea haidarum in Canada. Committee on the Status of Endangered Wildlife in Canada. Ottawa. vi + 41 pp. (www.sararegistry.gc.ca/status/status_e.cfm) Edie, A. 2001. Update COSEWIC status report on the Ermine haidarum subspecies Mustela erminea haidarumi in Canada, in COSEWIC assessment and update status report on the Ermine haidarim subspecies Mustela erminea haidarum in Canada. Committee on the Status of Endangered Wildlife in Canada. Ottawa. 1-41 pp. Youngman, P. 1984. COSEWIC status report on the Ermine Mustela erminea haidarumi (Queen Charlotte Islands population) in Canada. Committee on the Status of Endangered Wildlife in Canada. Ottawa. 14 pp. Production note: COSEWIC would like to acknowledge David Kirk for writing the status report on the Ermine, haidarum subspecies (Mustela erminea haidarum), prepared under contract with Environment Canada. Modifications to the status report after acceptance of the provisional report were overseen by Graham Forbes, Co-chair of the COSEWIC Terrestrial Mammals Specialist Subcommittee (TM SSC), based on comments from jurisdictions, external experts, the TM SSC, and COSEWIC members. For additional copies contact: COSEWIC Secretariat c/o Canadian Wildlife Service Environment Canada Ottawa, ON K1A 0H3 Tel.: 819-938-4125 Fax: 819-938-3984 E-mail: COSEWIC/[email protected] http://www.cosewic.gc.ca Également disponible en français sous le titre Ếvaluation et Rapport de situation du COSEPAC sur L’hermine de la sous-espèce haidarum (Mustela erminea haidarum) au Canada. Cover illustration/photo: Ermine haidarum subspecies — Source: Janet Gifford. Her Majesty the Queen in Right of Canada, 2015. Catalogue No. CW69-14/720-2015E-PDF ISBN 978-0-660-02613-8 COSEWIC Assessment Summary Assessment Summary – May 2015 Common name Ermine haidarum subspecies Scientific name Mustela erminea haidarum Status Threatened Reason for designation This genetically distinct subspecies of Ermine is known only from Haida Gwaii. The species appears to have declined to small population size due to habitat changes associated with the introduction of Black-tailed Deer, and possible competition for food with an increasing population of Pacific Marten. A comparison of results of recent, intensive sampling efforts with historical trapping records suggests a decline in numbers, and that the population is expected to continue to decline due to ongoing threats. Occurrence British Columbia Status history Designated Special Concern in April 1984. Status re-examined and designated Threatened in May 2001 and May 2015. iii COSEWIC Executive Summary Ermine haidarum subspecies Mustela erminea haidarum Wildlife Species Description and Significance The Ermine, haidarum subspecies (Mustela erminea haidarum, hereafter ‘Haida Ermine’) is a subspecies of Ermine (Short-tailed Weasel). It has a typical weasel form, with a small face, short, oval ears, and a slender, elongated body with a furred, black-tipped tail. The summer pelage changes from reddish-brown upperparts and creamy-white lower parts to white in winter. The subspecific status of Haida Ermine is based on unique morphometric characters and is supported by genetic analyses. The Haida Ermine has been isolated from the mainland for approximately 11,000 years and is significant as evidence of the existence of a glacial refugium in the north Pacific coast, and one of four genetic clades of Ermine worldwide. Distribution Based on present taxonomy, the Haida Ermine occurs only on Haida Gwaii Archipelago (Queen Charlotte Islands), British Columbia. It is known definitely to occur on Graham, Moresby, Louise, and Burnaby Islands, though it likely occurs on other smaller islands in the Archipelago as well. Habitat Haida Ermine records have occurred from sea level to 800 m asl, but most records exist below 350 m in coniferous forest of the Submontane Wet Hypermaritime biogeoclimatic zone. The Haida Ermine may be rarer in western, higher elevation and wetter locations on Haida Gwaii. Biology Relatively little is known about the biology of the Haida Ermine. Based on Ermine biology on the mainland, which should be similar among subspecies, Haida Ermine likely breed in the summer/autumn, and have one litter of 4 - 6 kits the following spring. The lifespan of most individuals is less than two years. Haida Ermine are opportunistic predators that rely on small mammals, birds, and invertebrates, and scavenge on Sitka Black-tailed Deer (Odocoileus hemionus sitkensis). iv Population Sizes and Trends Surveys confirm that Haida Ermine are very rare on Haida Gwaii. Intensive surveys have been conducted to locate the species but since the mid-1990s have yielded fewer than 40 verified (or probable) records. Population estimate is unknown, but based on available data the population size likely is fewer than 1000 mature individuals. A historical population decline since the 1950s is inferred based on decreased capture success and future declines are predicted because of ongoing threats. Threats and Limiting Factors Historically, Haida Ermine likely had a naturally low population size because of a limited prey base, and are likely to decline in the future due to various threats. The main threats to the Haida Ermine are habitat changes from increased competition and predation associated with various wildlife species introductions on Haida Gwaii. Introduced Deer have severely reduced understorey vegetation in much of the known Haida Ermine range, which has likely increased mortality rates from predators, and reduced populations of preferred prey species for Haida Ermine. The native Pacific Marten (Martes caurina) population has increased, likely from the introduction of Deer (a source of carrion) and Red Squirrel (Tamiasciurus hudsonicus). Pacific Marten compete with Haida Ermine for the limited food base, and also may be a predation threat. Unlike Pacific Marten, Haida Ermine likely do not benefit from the introduction of Red Squirrel and rats. Haida Ermine are trapped accidentally in traps set for Pacific Marten. The low Haida Ermine population may be impacted by trapping but the threat is difficult to quantify because trap effort is unknown. Rat eradication programs on several islands in Gwaii Haanas National Park Reserve likely have not impacted Haida Ermine. Protection, Status, and Ranks The rounded global Nature Serve rank is G5T2 (imperilled) for Haida Ermine. It has a national rank of N2 (nationally imperilled). Haida Ermine were assessed in 2001 as Threatened under the Species at Risk Act. Provincially, Haida Ermine is ranked as an S2 species (Imperilled), is on the provincial Red List, and is a candidate for endangered or threatened status in British Columbia. Intentional trapping of Haida Ermine has not been permitted since 1985. Approximately half of the islands where Haida Ermine have been recorded are protected by national and provincial protected areas but their value to Haida Ermine is unclear because threats are related to introduced species, and accidental mortality from trapping Pacific Marten, rather than forest harvest. Pacific Marten trapping is permitted in provincial and national protected areas, but is presently inactive within Gwaii Haanas National Park Reserve. v TECHNICAL SUMMARY Mustela erminea haidarum Ermine haidarum subspecies Hermine de la sous-espèce haidarum Range of occurrence in Canada: Haida Gwaii, British Columbia Demographic Information Generation time; Calculated as [1/estimated annual adult mortality rate] + 2 to 3 years estimated age of first reproduction). The provided range incorporates highly variable 1st year mortality rates recorded in studies on Ermine elsewhere. Is there an inferred and projected continuing decline in number of mature Yes individuals? Declines likely to continue because impact of Deer over-browsing increases over time, and Deer populations are likely to persist. Competition with Pacific Marten for food expected to continue. Estimated percent of continuing decline in total number of mature individuals Unknown within 4 - 6 years. [Observed, estimated, inferred, or suspected] percent [reduction or increase] in Unknown total number of mature individuals over the last 10 years. [Projected or suspected] percent [reduction or increase] in total number of Unknown mature individuals over the next 10 years]. [Observed, estimated, inferred, or suspected] percent [reduction or increase] in Unknown total number of mature individuals over any 10-year period, over a time period including both the past and the future. Are the causes of the decline clearly reversible and understood and ceased? No Declines likely to continue because impact of Deer over-browsing increases over time, and Deer populations are likely to persist. Competition with Pacific Marten for food is expected to continue. Are there extreme fluctuations in number of mature individuals? Unknown Extent and Occupancy Information Estimated extent of occurrence