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BC Conservation Data Centre: Conservation Status Report

Pituophis catenifer deserticola
Gophersnake, deserticola subspecies

 
Scientific Name: Pituophis catenifer deserticola
English Name: Gophersnake, deserticola subspecies
   
Provincial Status Summary
Status: S3
Date Status Assigned: March 30, 2018
Date Last Reviewed: April 01, 2025
Reasons: This subspecies of snake is restricted to the grasslands and shrub steppe of a few southern interior valleys in BC. It faces significant threats including road mortality, poisoning, habitat loss and fragmentation.
 
Range
Range Extent: F = 20,000-200,000 square km
Range Extent Estimate (km2): 46,921
Range Extent Comments: This subspecies of gophersnake is found within the dry interior of B.C. and includes the warm, dry grassland valleys of the Thompson and Okanagan rivers, Fraser River Valley from Lillooet north to Big Bar Creek, Lower Nicola River Valley, Similkameen River Valley, from the international boundary to Hedley, and Kettle River Valley from Rock Creek to Christina Lake (COSEWIC 2013l). The BC CDC calculated the range to be approximately 47,000 km2, based on occurrences mapped as of 2017. Using all records from GBIF (accessed 6 January 2025), there have been more records, but not a change in range extent.
Area of Occupancy (km2): G = 501-2,500
Area of Occupancy Estimate (km2): 2,144
Area of Occupancy Comments: The BC CDC calculated the area of occupancy to be 2,144 km2 (536 2x2 grid cells) based on occurrences mapped as of 2017 (same number mapped in 2025), but this value is should be considered a minimum. The AOO may also be slightly higher based on current iNaturalist records, but still within the range indicated (iNaturalist, accessed 6 January 2025).
 
Occurrences & Population
Number of Occurrences: DE = 81 to >300
Comments: As of January 2025, the BC CDC has 66 occurrences mapped; however this is likely an underestimate as other observations are known (accessed 6 January 2025) which may represent new element occurrences. Another factor is that Gophersnakes are not easily detected, as they spend considerable periods of time underground or under cover. Bertram et al. (2001) found that 3 radio-tagged gophersnakes were visible to the investigator during only 43% of their relocations, and even on the surface this species could be overlooked due to their cryptic colouration (COSEWIC 2013l). As of 2012, snake inventories within the range of this species have been conducted in the South Okanagan and Lower Similkameen (Sarell 1993, Hobbs and Sarell 2001, Iredale 2006), the Kettle watershed (Sarell et al. 1998), the Thompson Fraser (Hobbs 2001, Iredale 2006) and the Cariboo (Hobbs and Sarell 2002).
Number of Occurrences with Good Viability / Ecological Integrity: U = Unknown
Comments: There are no occurrences with known good viability. All are impacted by a number of threats. The most ubiquitous of these threats is motorized traffic (M. Sarell, pers. comm. 2008).
Number of Occurrences Appropriately Protected & Managed: C = 4 - 12
Comments: 2017: "Only 10% of the suitable habitat for the Great Basin Gopher Snake in B.C. is located within protected areas (provincial parks/ecological reserves, National Wildlife Areas, Wildlife Management Areas, private conservation holdings); most of the remainder was unprotected provincial Crown land..." (COSEWIC 2013l).

2012: Analysis showed that the majority of suitable habitat for this species exists on unprotected Crown land, with relatively little formally protected lands (including Protected Areas, Wildlife Habitat Areas, private conservation). The Kettle population, however, is situated primarily on private lands with virtually no habitat protected. Although Crown land dominates the suitable habitat in the Thompson-Nicola population, more of the best habitat is on private land, and only about 6% of habitat is protected. The Fraser and Okanagan-Similkameen populations have the highest amounts of good habitat protected, at approximately 15% and 13%, respectively (Haney and Sarell 2005). Although Gopher Snakes appear to be in many of the protected areas in the Okanagan Valley, most of these parks and reserves are too small to provide all of the different habitat types required by the snakes, especially in the south Okanagan. The population at Vaseux Lake is partially protected by a complex of protected areas. This species is listed as Identified Wildlife under the Forest and Range Practices Act. There are between 7 and 11 Wildlife Habitat Areas that have been established that may contain dens used by the Gopher Snake (CDC 2006) and possibly more given communal denning with other snakes. At least two den sites are protected by ecological reserves, however many snakes are still killed on roads on or nearby the reserves (Waye and Shewchuck 2002).
Population Size: E = 2,500 - 10,000 individuals
Comments: From COSEWIC 2013l: "Gopher Snakes are difficult to census due to their cryptic nature and fossorial habits, their wide but scattered distribution in British Columbia, and their frequent misidentification by members of the public (Bertram et al. 2001; Southern Interior Reptile and Amphibian Recovery Team 2008)." There are likely less than 10,000 individuals, but solid data is not available. This is still the case in 2025. The estimate in 2002 was fewer than 5000 mature individuals (COSEWIC 2002h), but this was likely an underestimate.

This subspecies occurs in four discrete populations in the dry interior of B.C. with its two southern populations, the Kettle (Grand Forks and Midway) and the Okanagan-Similkameen, connected to populations south of the international border but are themselves disjunct within BC (COSEWIC 2002h; Ovaska and Sopuck 2004; Haney and Sarell 2005). These populations are thought to have been one contiguous population during the Hypsothermic period 8,000 years ago; however, the most northerly populations (Thompson-Nicola and Fraser) have since become completely isolated (COSEWIC 2002h). These northern two populations are known to be connected at Lytton, and there is a possibility of connectivity through the Pavilion Valley (Haney and Sarell 2005).
 
Threats (to population, occurrences, or area affected)
Degree of Threat: B = High
Comments: The threats were last formally assessed in 2013 and are the results used for the current assessment (2025). The issues identified at that time are still present. The greatest identified threat to gophersnake is direct mortality from road traffic. Other significant threats include habitat loss and fragmentation from housing, agriculture, recreation, and fire suppression; potential diseases from invasive non-native/alien species; as well as direct harm or mortality from recreation, persecution, and pollution (Southern Interior Reptile and Amphibian Working Group 2016c). Rodent control via strychnine may be a serious threat by poisoning as well as a reduction in the number of prey items available (Bishop et al. 2016).

2012: There has been a significant loss of habitat as more agricultural land is converted from range land and shrub-steppe to orchards, vineyards and houses. There has been increased mortality through intentional and accidental killings in agricultural areas. Haying has been cited as the largest source of mortality in the Cariboo (Hobbs and Sarell 2002). The habitats used for den and nest sites in the Thompson region are restricted and are in danger of being shaded out by encroaching forests due to lack of frequent wildfires through fire suppression (COSEWIC 2002h). Overgrazing by livestock can reduce cover and quality of foraging areas (Ovaska and Sopuck 2004) and grazing often exists even in Wildlife Habitat Areas established to protect this species.

Increased road networks and increased traffic may result in increased human-induced mortality. This species is very slow moving and therefore vulnerable to road mortality and to the vagrancies of those who kill snakes on sight, particularly large ones such as the gopher snake which looks similar to a rattlesnake. Their tendency to warm themselves on pavement increases their roadkill vulnerability (Storm and Leonard 1995). They do appear to be tolerant of nondestructive intrusion. Rodent control could affect prey availability. Agricultural activities and off-road vehicles may damage Gopher Snake eggs in rodent burrows.
 
Trend (in population, range, area occupied, and/or condition of occurrences)
Short-Term Trend: U = Unknown
Comments: No data, but presumed to be declining based on historical and current habitat loss and fragmentation from development and road mortality (COSEWIC 2013; Southern Interior Reptile and Amphibian Working Group 2016c). A study looking at strychnine use on pocket gophers found, using models, that in an area of high gophersnake density (0.4/ha), consumption of these poisoned pocket gophers could result in a loss of 50% of adults in 25 years. A lower density population (0.1/ha) could result in a decline of 35.5% of adults in 25 years (Bishop et al. 2016).
Long-Term Trend: U = Unknown
Comments: From COSEWIC 2013l: "Few data are available on abundance or population trends. Gophersnakes are difficult to census due to their cryptic nature and fossorial habits, their wide but scattered distribution in British Columbia, and their frequent misidentification by members of the public (Bertram et al. 2001; Southern Interior Reptile and Amphibian Recovery Team 2008)." The habitat used by P.c. deserticola has been reduced in quality and quantity, thus it is likely the numbers of P.c. deserticola has declined to a corresponding degree.
 
Other Factors
Intrinsic Vulnerability: B=Moderately vulnerable
Comments: This species is at the northern limit of its range in Canada. It has a relatively low fecundity compared to smaller colubrid snakes (Ovaska and Sopuck 2004). In Canada, females do not reproduce every year and possibly mature at a later age (>5 years) laying 2-8 eggs (average 4.6). If Gophersnakes take longer to mature in BC than in more southerly populations, then the populations would be slower to recover from declines than ones further south (COSEWIC 2002h).
Environmental Specificity: B=Narrow. Specialist or community with key requirements common.
Comments: P.c. deserticola is restricted to grasslands, shrub steppe, and dry open forest of the ponderosa pine - bunchgrass biogeoclimatic zone of a few (5) south Interior valleys (Cannings et al. 1999). The habitat occupied by this species makes up less than 10% of the total area of British Columbia (COSEWIC 2002h). The presence of suitable hibernation sites that allow the snakes to escape subfreezing conditions may be in short supply (Ovaska and Sopuck 2004).
Other Rank Considerations: The four populations of Gopher Snakes in British Columbia are becoming increasingly fragmented (COSEWIC 2002h). The Okanagan-Similkameen population is considered a contiguous population, although there is speculation whether the central Okanagan maintains metapopulation connectivity. Human development across private lands along the valley floor and valley sides threatens to sever this subpopulation in the valley centre, and is increasing fragmentation elsewhere (Haney and Sarell 2005)."The cities of Kelowna and Vernon have severely disrupted habitat connectivity and presumably virtually severed northsouth gene flow in the Okanagan. The growth of the city of Kamloops has similarly disrupted habitat connectivity and has probably almost severed east-west gene flow in the Thompson-Fraser-Nicola area." (COSEWIC 2013l).
 
Information Gaps
Research Needs:
Inventory Needs:
 
Stewardship
Protection:
Management:
 
Version
Author: Ramsay, L. (2025), L. Gelling (2012, 2018), Westereng, L. and M. Sarell (2008);, Cannings, S. and L. Ramsay (1998);
Date: January 06, 2025
 
References
BC Conservation Data Centre: Conservation Data Centre Mapping Service [web application]. 2006. Victoria, British Columbia, Canada. Available: http://maps.gov.bc.ca/imf50/imf.jsp?site=cdc.
BC Southern Interior Reptile and Amphibian Recovery Team. 2005. National Recovery Strategy for the Great Basin Gopher Snake (Pituophis catenifer deserticola) in Canada. National Recovery Plan No. XX. Recovery of Nationally Endangered Wildlife (RENEW). Ottawa, Ontario. XX pp
Bertram, N., K. W. Larsen, and J. Surgeon. 2001. Identification of critical habitat and conservation issues for the Western Rattlesnake and Great Basin Gopher Snake within the Thompson-Nicola region of British Columbia. Unpublished report prepared for BC Ministry of Water, Lands, and Air Protection, Kamloops, BC.
Bishop, C.A., Williams, K.E., Kirk, D.A., Nantel, P., Reed, E. and Elliott, J.E., 2016. A population model of the impact of a rodenticide containing strychnine on Great Basin Gophersnakes (Pituophis catenifer deserticola). Ecotoxicology, 25, pp.1390-1405.
Cannings, S.G., L.R. Ramsay, D.F. Fraser, and M.A. Fraker. 1999c. Rare amphibians, reptiles and mammals of British Columbia. Wildl. Branch and Resour. Inv. Branch, B.C. Minist. Environ., Lands and Parks, Victoria, B.C. 198 pp.
Collins, J. T. 1990. Standard common and current scientific names for North American amphibians and reptiles. 3rd ed. Society for the Study of Amphibians and Reptiles. Herpetological Circular No. 19. 41 pp.
COSEWIC. 2002h. COSEWIC assessment and status report on the Gophersnake Pituophis catenifer in Canada. Committee on the Status of Endangered Wildlife in Canada. Ottawa. vii + 33 pp.
COSEWIC. 2013l. COSEWIC assessment and status report on the Great Basin Gophersnake Pituophis catenifer deserticola in Canada. Committee on the Status of Endangered Wildlife in Canada. Ottawa. xii + 53 pp.
Forest Practices Code. 1997. Gopher Snake (ssp. deserticola) in Species and Plant Community Accounts for Identified Wildlife: Vol. 1. B.C. Minist. For. and B.C. Environ. 184pp.
GBIF.org. 2025p. GBIF. Occurrence download for Pituophis catenifer. Accessed 7 January 2025.
Gregory, L.A., and P.T. Gregory. 1999. The Reptiles of British Columbia, A taxonomic catalogue. B.C. Minist. Environ., Lands and Parks, Victoria. Wildl. Bull. B-88. 28pp.
Gregory, P.T., and R.W. Campbell. 1984. The Reptiles of British Columbia. Royal B.C. Mus. Handb. 102pp.
Haney, A. and M. Sarell. 2005. Conservation analysis for the Great Basin Gophersnake (Pituophis catenifer deserticola in British Columbia). Report prepared for the Ministry of Water, Land and Air Protection, and Ministry of Forests, Victoria, BC. 30pp.
Hobbs, J. 2001d. Gopher snakes (and cohorts): An assessment of selected den sites in the Thompson/Fraser and Okanagan snake populations. Unpubl. rep. prepared for Minist. Water., Lands and Air Protection, Kamloops, BC. 45pp.
Hobbs, J. and Sarell, M. 2002c. An assessment of Racer and Gopher snake habitat in the Williams Lake and 100-Mile Forest Districts. Unpubl. rep. prepared for Minist. Environ., Lands and Parks, Williams Lake, BC. 48pp.
Hobbs, J., and M. Sarell. 2001. Gopher snakes (and cohorts): An assessment of selected den sites in the Penticton, Vernon, Merritt and Boundary Forest Districts. Unpubl. rep. prepared for Minist. Environ., Lands and Parks, Kamloops, BC. 47pp.
Hobson & Associates. 2006. Environmental issues and options for the South Okanagan Regional Growth Strategy. Prepared for the Environmental Advisory Committee, Regional District of Okanagan-Similkameen.
iNaturalist community. 2025g. Observations of Pituophis catenifer deserticola from British Columbia, Canada. Exported from www.inaturalist.org on 6 January 2025.
Iredale, F.J. 2006h. Fall inventory for Northern Pacific Rattlesnake, Racer, and Gopher Snakes 2006 MOE Regions 3 and 8. BC Conservation Core report prepared for Ministry of Environment, Kamloops, BC. 38pp.
Nussbaum, R. A., E. D. Brodie, Jr. and R. M. Storm. 1983. Amphibians and reptiles of the Pacific Northwest. University Press of Idaho, Moscow, Idaho. 332 pp.
Ovaska, K., and L. Sopuck. 2004. Indicators and methods for monitoring the effectiveness of Gopher Snake Wildlife Habitat Areas. Final report prepared for Minist. Water, Land and Air Prot. Victoria, BC. 62pp.
Parker, W.S. and W.S. Brown. 1980. Comparative ecology of two colubrid snakes, Masticophis t. taeniatus and Pituophis melanoleucus deserticola in northern Utah. Milwaukee Pub. Mus.Publ. Biol. and Geol. No. 7, i-viii+104 pp.
Sarell, M. 2003. An inventory strategy for the Gopher Snake (Pituophis catenifer deserticola) in south-central British Columbia. Report prepared for the Ministry of Water, Lands, and Air Protection, Penticton, BC.
Sarell, M.J. 1993. Snake hibernacula in the South Okanagan. Unpubl. rep. submitted to Wildl. Program, B.C. Environ., Penticton. 19pp. + appendix.
Sarell, M.J., A. Haney, and S. Robertson. 1998. Inventory of red and blue-listed wildlife within the Southern Boundary Forest District: amphibians, reptiles, birds and bats. Year two of two. Unpublished report prepared for BC Environment, Penticton, BC, and Forest Renewal British Columbia.
Shewchuk, C. H. 1996. The natural history of reproduction and movement patterns in the Gopher Snake (Pituophis melanoleucus) in Southern British Columbia. Unpublished M.Sc. thesis, Department of Biology, University of Victoria, Victoria, BC.
Shewchuk, C.H., and H.L. Waye. 1995a. Status report for the gopher snake in British Columbia. Unpubl. rep., B.C. Minist. Environ., Lands and Parks, Wildl. Branch, Victoria.
Southern Interior Reptile and Amphibian Working Group. 2016c. Recovery plan for the Gopher Snake, deserticola subspecies (Pituophis catenifer deserticola) in British Columbia. Prepared for the B.C. Ministry of Environment, Victoria, BC. 36 pp.
Storm, R.M., and W.P. Leonard, eds. 1995. Reptiles of Washington and Oregon. Seattle Audubon Soc., The Trailside Ser., Seattle, WA. 176pp.
 

Please visit the website Conservation Status Ranks for information on how the CDC determines conservation status ranks. For global conservation status reports and ranks, please visit the NatureServe website http://www.natureserve.org/.

Suggested Citation:

B.C. Conservation Data Centre. 2025. Conservation Status Report: Pituophis catenifer deserticola. B.C. Minist. of Environment. Available: https://a100.gov.bc.ca/pub/eswp/ (accessed Nov 4, 2025).