COSEWIC Status Appraisal Summary on the Timber Rattlesnake Crotalus horridus in Canada
COSEWIC status appraisal summaries are working documents used in assigning the status of wildlife species suspected of being at risk in Canada. This document may be cited as follows:
COSEWIC. 2010. COSEWIC status appraisal summary on the Timber Rattlesnake Crotalus horridus in Canada. Committee on the Status of Endangered Wildlife in Canada. Ottawa. ix pp.
(Species at Risk Status Reports)
For additional copies contact:
c/o Canadian Wildlife Service
Également disponible en français sous le titre Sommaire du statut de l’espèce du COSEPAC sur le crotale des bois (Crotalus horridus) au Canada.
© Her Majesty the Queen in Right of Canada, 2011.
Catalogue No.: CW69-14/2-6-2011E-PDF
Status Appraisal Summary
Current COSEWIC Assessment:
1 An earlier version of the quantitative criteria was used by COSEWIC from October 1999 to May 2001 and is available on the COSEWIC website: http://www.cosewic.gc.ca/eng/sct0/original_criteria_e.cfm
Recommendation: Update to the status report NOT required (wildlife species’ status category remains unchanged)
Evidence (indicate as applicable):
List of Authorities Contacted to Review the Status Appraisal
The Status Appraisal Summary was sent to the following jurisdictions for review:
- Canadian Wildlife Service
- Parks Canada Agency
- Province of Ontario
The following persons responded to an email query sent March, 2010:
- Ronald Brooks.University of Guelph.
- Ross MacCulloch. Royal Ontario Museum.
- Michael Oldham. Ontario Natural Heritage Information Centre.
- Wayne Weller. Ontario Power Generation.
The following persons were also contacted via email, but did not respond:
- Bob Johnson. Toronto Zoo.
- Andrew Lentini. Toronto Zoo.
- Angela McConnell. Environment Canada.
Sources of Information
Allsteadt, J., A.H. Savitzky, C.E. Petersen and D. Naik. 2006. Geographic variation in the morphology of Crotalus horridus (Serpentes: Viperidae). Herpetological Monographs. (20): 1-63.
Clark, A.M., P.E. Moler, E.E. Possardt, A.H. Savitzky, W.S. Brown and B.W. Bowen. 2003. Phylogeography of the timber rattlesnake (Crotalus horridus) based on mtDNA sequences. Journal of Herpetology. 37(1): 145-154.
COSEWIC 2001. COSEWIC assessment and update status report on the timber rattlesnake Crotalus horridus in Canada. Committee on the Status of Endangered Wildlife in Canada. Ottawa. vi + 24 pp.
Environment Canada. 2009. Recovery Strategy for the Timber Rattlesnake (Crotalus horridus) in Canada [Proposed]. Species at Risk Act Recovery Strategy Series. Environment Canada, Ottawa. v + 17 pp.
Pisani, G.R., J.T. Collins, and S.R. Edwards. 1973. A re-evaluation of the subspecies of Crotalus horridus. Transactions of the Kansas Academy of Science 75(3):255-263.
Range of occurrence in Canada (province/territory/ocean): Ontario
|Generation time (usually average age of parents in the population; indicate if another method of estimating generation time indicated in the IUCN guidelines(2008) is being used)||6 yrs|
|Is there an [observed, inferred, or projected] continuing decline in number of mature individuals?||NA|
|Estimated percent of continuing decline in total number of mature individuals within [5 years or 2 generations]||NA|
|[Observed, estimated, inferred, or suspected] percent [reduction or increase] in total number of mature individuals over the last [10 years, or 3 generations].||NA|
|[Projected or suspected] percent [reduction or increase] in total number of mature individuals over the next [10 years, or 3 generations].||NA|
|[Observed, estimated, inferred, or suspected] percent [reduction or increase] in total number of mature individuals over any [10 years, or 3 generations] period, over a time period including both the past and the future.||NA|
|Are the causes of the decline clearly reversible and understood and ceased?||NA|
|Are there extreme fluctuations in number of mature individuals?||NA|
Extent and Occupancy Information
|Estimated extent of occurrence||0 km2|
|Index of area of occupancy (IAO)|
(Always report 2x2 grid value).
|Is the total population severely fragmented?||NA|
|Number of locations*||0|
|Is there an [observed, inferred, or projected] continuing decline in extent of occurrence?||NA|
|Is there an [observed, inferred, or projected] continuing decline in index of area of occupancy?||NA|
|Is there an [observed, inferred, or projected] continuing decline in number of populations?||NA|
|Is there an [observed, inferred, or projected] continuing decline in number of locations*?||NA|
|Is there an [observed, inferred, or projected] continuing decline in [area, extent and/or quality] of habitat?||NA|
|Are there extreme fluctuations in number of populations?||NA|
|Are there extreme fluctuations in number of locations*?||NA|
|Are there extreme fluctuations in extent of occurrence?||NA|
|Are there extreme fluctuations in index of area of occupancy?||NA|
Number of Mature Individuals (in each population)
|Population||N Mature Individuals|
Threats (actual or imminent, to populations or habitats)
Rescue Effect (immigration from outside Canada)
|Status of outside population(s)?||Global G4;|
USA N4. Declining across most of its USA range. Status in USA states: Alabama (S5), Arkansas (S4), Connecticut (S1), District of Columbia (SH), Florida (S3), Georgia (S4), Illinois (S3), Indiana (S2), Iowa (S3), Kansas (S3), Kentucky (S4), Louisiana (S3S4), Maine (SX), Maryland (S3), Massachusetts (S1), Minnesota (S2), Mississippi (S5), Missouri (S3S4), Nebraska (S1), New Hampshire (S1), New Jersey (S1), New York (S3), North Carolina (S3), Ohio (S1), Oklahoma (S3), Pennsylvania (S3S4), Rhode Island (SX), South Carolina (SNR), Tennessee (S4), Texas (S4), Vermont (S1), Virginia (S4), West Virginia (S3), Wisconsin (S2S3): States bordering Canada are in bold type. (Natureserve last updated 2006.)
|Is immigration known or possible?||It is quite unlikely, but remotely possible|
|Would immigrants be adapted to survive in Canada?||Possibly|
|Is there sufficient habitat for immigrants in Canada?||Probably|
|Is rescue from outside populations likely?||No|
Status and Reasons for Designation
|Reasons for designation at previous assessment (May 2001):|
The Timber Rattlesnake once occupied much of the Niagara Escarpment and other regions of southern Ontario, but has not been seen in the province since 1941 despite intensive searches and the fact that it is easy to identify.
Applicability of Criteria
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, 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.
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 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.
- 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)*
- 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)**
- A wildlife species that has been evaluated and found to be not at risk of extinction given the current circumstances.
- Data Deficient (DD)***
- 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.
- Date Modified: