Sharp-tailed Snake Pacific Coast population
Scientific Name: Contia tenuis
Other/Previous Names: Sharp-tailed Snake
Taxonomy Group: Reptiles
COSEWIC Range: British Columbia
COSEWIC Assessment Date and Status Change: December 2021
COSEWIC Status: Threatened
COSEWIC Status Criteria: B1ab(iii,v)+2ab(iii,v)
COSEWIC Reason for Designation: The Canadian distribution of this tiny snake is confined to a small area in southeastern Vancouver Island and the southern Gulf Islands of British Columbia. Increased search effort since the last assessment has resulted in the documenting of five previously unrecorded subpopulations, extending the known range. The number of mature individuals is thought to be ~12,000. These snakes continue to face threats from introduced species, ongoing development, off-trail recreation, habitat fragmentation by roads, and increasing droughts associated with climate change. The explosive growth of the introduced invasive Common Wall Lizard in recent years is of concern; these lizards may prey on eggs and hatchling snakes and have the potential to eliminate or greatly reduce some subpopulations in the near future. Re-evaluation of the degree of population fragmentation and better understanding of the snakes’ distribution and abundance contributed to the change in status from Endangered to Threatened.
COSEWIC History of Status Designation: Designated Endangered in April 1999. Status re-examined and confirmed in October 1999 and November 2009. Status re-examined and designated Threatened in December 2021.
SARA Status: Schedule 1, Endangered
Date of Listing (yyyy-mm-dd): 2003-06-05
Please note that this information is provided for general information purposes only. For the most up to date and accurate list of species listed under the Species at Risk Act, please see the Justice Laws Website.
Image of Sharp-tailed Snake
The Sharp–tailed Snake, Contia tenuis (Reptilia: Squamata: Dipsadidae), is a small, slender snake with adults reaching about 205–455 mm in total length. The body scales are smooth and unkeeled, and there is a thorn–like scale at the tip of the tail, from which the species derives its common name. The back and sides are red– or yellow–brown, occasionally greyish, and the underside is banded with black and white bars. Distinct longitudinal stripes are lacking. Currently, only one species of Contia is recognized, but morphological and genetic evidence indicate that there are two forms, probably representing sister species: a long–tailed form in coastal California and parts of southern Oregon, and a shorter–tailed form in the interior of California, parts of Oregon and Washington, and southwestern British Columbia. (Updated 2017/05/25)
Distribution and Population
The geographic range of the species extends from southwestern British Columbia south to the Sierra Nevada and to the central coast of California in western North America. In Canada, the Sharp–tailed Snake is known from southern Vancouver Island and four of the Gulf Islands in the Strait of Georgia (North Pender, South Pender, Saltspring, and Galiano), British Columbia. Currently, there are records of the species from eight areas, each of which probably represents a separate population. Four populations are on extreme southern Vancouver Island: one in the District of Metchosin and three on the Saanich Peninsula. There is one population on each of Saltspring, North Pender, South Pender, and Galiano Islands. The larger populations contain several clusters of records. (Updated 2017/05/25)
The snakes inhabit relatively open–canopy woodlands dominated by Douglas–fir, Arbutus, and/or Garry Oak within the Coastal Douglas–fir Biogeoclimatic Zone. Habitats of the species are naturally fragmented, exacerbated by human habitation, roads, and other developments. The snakes are often found in or near small openings on rocky outcrops and hillsides. Occupied sites usually have a southern exposure, shallow soil and leaf litter, and a high cover of rock. Rocky slopes with a southern exposure probably provide warm microhabitats required for egg–laying and thermoregulation. Requirements for hibernation sites in winter and retreat sites in summer are poorly known, but the snakes probably occupy areas year–round, as there is no evidence of longer migratory movements. (Updated 2017/05/25)
The Sharp–tailed Snake is secretive and semi–fossorial, making it difficult to find and study. As a result, little is known of its life history and habits. In spring or early summer, females lay a clutch of about 3 to 5 eggs, which hatch by autumn. Capture–recapture studies on North Pender Island indicate that annual survival rates are relatively high (66–75%) and show a positive correlation with body size. Individual snakes can live to 9 years or more. Surface activity of the Sharp–tailed Snakeis highly seasonal and largely restricted to relatively cool periods in spring and autumn. The snakes have also been found active on warm summer nights. They tend to form aggregations, particularly in the spring. (Updated 2017/05/25)
The rarity of the species in Canada is likely due to both climatic and historical factors. The species exists at the northern limits of its range in southern British Columbia, and present–day populations are probably relicts from a more extensive past distribution. Main immediate threats consist of habitat loss, degradation, and fragmentation throughout the species’ Canadian range. Expanding rural or urban development and associated roads and other infrastructure threaten populations at most known sites. (Updated 2017/05/25)
The Sharp-tailed Snake, Pacific Coast population, is protected under the federal Species at Risk Act (SARA). More information about SARA, including how it protects individual species, is available in the Species at Risk Act: A Guide.
Provincial and Territorial Protection
Status of Recovery Planning
Recovery Strategies :
Name Recovery Strategy for the Sharp-tailed Snake (Contia tenuis) in Canada
Status First posting on SAR registry
Recovery Progress and Activities
Summary of Progress to Date The Sharp-tailed Snake recovery team aims to ensure the persistence of all known populations of this rare snake. Since the snake has cryptic habits and is difficult to survey, the team considers it likely that additional populations exist. Identifying additional populations and encouraging stewardship of their habitat are key priorities of the team. As of 2005, two new sites have been found - one on southern Vancouver Island and one on Saltspring Island. In addition, the area of occupancy at previously known sites has increased slightly due to new records. The majority of Sharp-tailed Snake habitat is on private land, making landowner involvement critical to the success of both research and recovery projects. Through ongoing outreach and stewardship projects, close working relationships have been fostered with many landowners who have discovered Sharp-tailed Snakes on their property. Summary of Research/Monitoring Activities A habitat assessment and inventory was conducted on federally owned properties on southern Vancouver Island during 2003 and 2004. Potentially suitable Sharp-tailed Snake habitat was identified through aerial photographs. Subsequent surveys to determine the presence of snakes were conducted at strategic sites in suitable habitat. So far, Sharp-tailed Snakes have been located on two Department of National Defense (DND) properties through this project. Habitat assessments were also conducted in 2002 for the Gulf Islands National Park Reserve, Gowlland Todd Provincial Park and for Capital Regional District Park lands in the vicinity of historical records (along the Galloping Goose Regional Trail right-of-way in Metchosin). However, as of 2005, no new Sharp-tailed Snake locations have been found in either of these places. Population monitoring is being conducted at the two DND properties and, in cooperation with landowners, on most privately-owned properties with Sharp-tailed Snakes. In order to more accurately identify potentially suitable habitat and to increase the effectiveness of habitat restoration activities, researchers require a more detailed understanding of the Sharp-tailed Snake’s habitat requirements. Results of habitat studies to date indicate that areas occupied by Sharp-tailed Snakes have more southerly aspects, high rock cover, shallow soil and litter, and sparse shrub cover. Summary of Recovery Activities As a result of outreach initiatives, many landowners and managers can now identify the Sharp-tailed Snake, recognize its habitat and know what options they have for habitat restoration and enhancement. This has resulted in the discovery by several landowners of Sharp-tailed Snakes on their properties. Between 2002 and 2004, habitat enhancement was conducted at three private properties with Sharp-tailed Snakes, including the construction of artificial hibernacula and nesting sites, as well as landscaping to increase habitat suitability. A conservation covenant was established in 2004 on a residential property on North Pender Island to provide long-term protection to habitat used by the Sharp-tailed Snake. The recovery team works directly with developers and land-use planners to incorporate the snake’s habitat requirements in development planning. Information on habitat protection measures for the snake has been provided to Islands Trust planners and North Pender Island Local Trust Committee Members, for their consideration in the revision of the North Pender Island Official Community Plan.
PLEASE NOTE: Not all COSEWIC reports are currently available on the SARA Public Registry. Most of the reports not yet available are status reports for species assessed by COSEWIC prior to May 2002. Other COSEWIC reports not yet available may include those species assessed as Extinct, Data Deficient or Not at Risk. In the meantime, they are available on request from the COSEWIC Secretariat.
15 record(s) found.
- COSEWIC Status Reports (1 record(s) found.)
- COSEWIC Assessments (1 record(s) found.)
- Response Statements (1 record(s) found.)
- Recovery Strategies (1 record(s) found.)
- Action Plans (1 record(s) found.)
- Critical Habitat Statements (1 record(s) found.)
- COSEWIC Annual Reports (1 record(s) found.)
- Permits and Related Agreements (6 record(s) found.)
- Consultation Documents (1 record(s) found.)
- Recovery Document Posting Plans (1 record(s) found.)
COSEWIC Status Reports
Response Statement - Sharp-tailed Snake (2010-12-02)This tiny snake is confined to a handful of isolated, small populations in southeastern Vancouver Island and the southern Gulf Islands of British Columbia. Most of these populations are threatened by development and may not be viable. Increased search effort since the last assessment has found three previously undiscovered populations. Despite this, it is likely that overall numbers are decreasing and threats continue unabated. Major threats include ongoing development, increasing human populations, off trail recreation, fragmentation by roads and stochastic effects on small populations.
Critical Habitat Statements
COSEWIC Annual Reports
COSEWIC Annual Report - 2010 (2010-09-03)Under Canada’s Species At Risk Act (SARA), the foremost function of COSEWIC is to “assess the status of each wildlife species considered by COSEWIC to be at risk and, as part of the assessment, identify existing and potential threats to the species”. During the past year, COSEWIC held two Wildlife Species Assessment Meetings and reviewed the status of 79 wildlife species (species, subspecies, populations). During the meeting of November 2009, COSEWIC assessed or reviewed the classification of the status of 28 wildlife species. COSEWIC assessed or reviewed the classification of an additional 51 wildlife species (species, subspecies and populations) during their April 2010 meeting. For species already found on Schedule 1 of SARA, the classification of 32 species was reviewed by COSEWIC and the status of the wildlife species was confirmed to be in the same category (extirpated - no longer found in the wild in Canada but occurring elsewhere, endangered, threatened or of special concern). The wildlife species assessment results for the 2009-2010 reporting period include the following: Extirpated: 6 Endangered: 39 Threatened: 16 Special Concern: 17 Data Deficient: 1 This report transmits to the Minister the status of 46 species newly classified as extirpated, endangered, threatened or of special concern, fulfilling COSEWIC’s obligations under SARA Section 24 and 25. A full detailed summary of the assessment for each species and the reason for the designation can be found in Appendix I of the attached report. Since its inception, COSEWIC has assessed 602 wildlife species in various risk categories, including 262 Endangered, 151 Threatened, 166 Special Concern and 23 Extirpated. In addition, 13 wildlife species have been assessed as Extinct. Also, to date, 46 wildlife species have been identified by COSEWIC as Data Deficient and 166 wildlife species were assessed as Not at Risk. This year has been a particularly productive year for COSEWIC’s Aboriginal Traditional Knowledge (ATK) Subcommittee. In April 2010 COSEWIC approved the Aboriginal Traditional Knowledge Process and Protocol Guidelines, providing clear and agreed principles for the gathering of Aboriginal Traditional Knowledge to carry out COSEWIC functions as required under Section 15(2) of SARA (See Appendix III of the attached report). We are grateful for the rich and enthusiastic contribution made by community elders and experts in helping the ATK Subcommittee prepare the ATK protocols.