Crotalus willardi obscurus
Harris, 1974
New Mexico Ridge-nosed Rattlesnake
T1T1Global Rank
Very high - highThreat Impact
Identity
Unique IDELEMENT_GLOBAL.2.100194
Element CodeARADE02131
Record TypeSPECIES
ClassificationSubspecies
Classification StatusStandard
Name CategoryVertebrate Animal
Endemicoccurs (regularly, as a native taxon) in multiple nations
KingdomAnimalia
PhylumCraniata
ClassReptilia
OrderSquamata
FamilyViperidae
GenusCrotalus
SynonymsCrotalus willardi silus
Other Common NamesNew Mexican ridge-nosed rattlesnake (EN) New Mexico ridge-nosed rattlesnake (EN)
Concept ReferenceCollins, 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.
Conservation Status
Rank MethodLegacy Rank calculation - Excel v3.1x
Review Date2018-11-26
Change Date1997-02-26
Edition Date2018-11-26
Edition AuthorsSchuhmann, A.
Threat ImpactVery high - high
Range Extent1000-20,000 square km (about 400-8000 square miles)
Number of OccurrencesUnknown
Rank ReasonsSmall range in the mountains of southern New Mexico and adjacent Arizona and northern Mexico; needs protection from overcollecting and habitat destruction/alteration (such as through intensive livestock grazing and fire).
Range Extent CommentsThis snake occurs locally in Animas Mountains (New Mexico), Peloncillo Mountains (Arizona and New Mexico), and Sierra de San Luis (Sonora and Chihuahua, Mexico) (Campbell et al. 1989, Holycross and Smith 1997, Campbell and Lamar 2004).
Threat Impact CommentsHistoric threats were primarily over-collecting and habitat alteration (e.g., heavy livestock grazing). Current threats include mortality associated with prescribed fire and wildfire, climate-related habitat shifting, and illegal collection (Davis et al. 2015).
Ecology & Habitat
Habitat
Primarily at high elevations in pine-oak woodland and pine-fir forest but also found in foothill canyons in pinyon-juniper woodland. Inhabits canyon bottoms with canopies of alder, box elder, maple, etc. (Stebbins 1985). Hides in leaf litter among cobbles and rocks; frequently climbs into trees and shrubs (Matthews and Moseley 1990).
Reproduction
Viviparous. Bears 2-9 young, August-September.
Terrestrial HabitatsWoodland - HardwoodWoodland - ConiferWoodland - MixedBare rock/talus/scree
Palustrine HabitatsRiparian
Other Nations (1)
United StatesN1
| Province | Rank | Native |
|---|
| New Mexico | S1 | Yes |
| Arizona | S1 | Yes |
References (19)
- Armstrong, B. L., and J. B. Murphy. 1979. The natural history of Mexican rattlesnakes. Univ. Kansas Museum Natural History Special Publication. No. 5. vii + 88 pp.
- Campbell, J. A., and E. D. Brodie, Jr., editors. 1992. Biology of the pit vipers. Selva, Tyler, Texas.
- Campbell, J. A., and W. W. Lamar. 1989. The venomous reptiles of Latin America. Comstock Publ. Associates, Division of Cornell Univ. Press, Ithaca, New York. xii + 425 pp.
- Campbell, J. A., and W. W. Lamar. 2004. The venomous reptiles of the Western Hemisphere. 2 volumes. Cornell University Press.
- 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.
- Crother, B. I. (editor). 2012. Scientific and standard English names of amphibians and reptiles of North America north of Mexico, with comments regarding confidence in our understanding. 7th edition. SSAR Herpetological Circular 39:1-92.
- Crother, B. I. (editor). 2017. Scientific and standard English names of amphibians and reptiles of North America north of Mexico, with comments regarding confidence in our understanding. 8th edition. SSAR Herpetological Circular 43:1-104. [Updates in SSAR North American Species Names Database at: https://ssarherps.org/cndb]
- Davis, M.A. 2008. Population dynamics of the New Mexico Ridge-nosed Rattlesnake (<i>Crotalus willardi obscurus</i>) in the Madrean Archipelago: a threatened species in a changing ecosystem. Thesis. Colorado State University, Fort Collins.
- Davis, M.A., M.R. Douglas, C.T. Web, M.L. Collyer, A.T. Holycross, C.W. Painter, L.K. Kamees, and M.E. Douglas. 2015. Nowhere to go but up: impacts of climate change on demographics of a short-range endemic (<i>Crotalus willardia obscurus</i>) in the Sky-Islands of Southwestern North America. PlosOne. June 26, 2015.
- Ernst, C. H. 1992. Venomous reptiles of North America. Smithsonian Institution Press, Washington, D.C. ix + 236 pp.
- Gloyd, H. 1940. The rattlesnakes. Chicago Academy Science, Special Publication No. 4.
- Holycross, A.T. 2002. Conservation Biology of Two Rattlesnakes. <i>Crotalus willardi obscurus</i> and <i>Sistrurus catenatus edwardsii</i>. Dissertation. Arizona State University, Tempe.
- Holycross, A.T., and M.E. Douglas. 2007. Geographic isolation, genetic divergence, and ecological non-exchangeability define ESUs in a threatened Sky-Island rattlesnake. Biological Conservation 134:142-154.
- Holycross, A. T., and S. W. Smith. 1997. Geographic distribution: CROTALUS WILLARDI OBSCURUS. Herpetological Review 28:97.
- Klauber, L. M. 1972. Rattlesnakes: their habits, life histories, and influence on mankind. Second edition. Two volumes. Univ. California Press, Berkeley.
- Lowe, C. H., C. R. Schwalbe, and T. B. Johnson. 1986. The venomous reptiles of Arizona. Arizona Game and Fish Department. ix + 115 pp.
- Matthews, J.R. and C.J. Moseley (eds.). 1990. The Official World Wildlife Fund Guide to Endangered Species of North America. Volume 1. Plants, Mammals. xxiii + pp 1-560 + 33 pp. appendix + 6 pp. glossary + 16 pp. index. Volume 2. Birds, Reptiles, Amphibians, Fishes, Mussels, Crustaceans, Snails, Insects, and Arachnids. xiii + pp. 561-1180. Beacham Publications, Inc., Washington, D.C.
- Stebbins, R. C. 1985a. A field guide to western reptiles and amphibians. Second edition. Houghton Mifflin Company, Boston, Massachusetts. xiv + 336 pp.
- U.S. Fish and Wildlife Service (USFWS). 2018. Endangered and Threatened Wildlife and Plants; Initiation of 5-Year Status Reviews of 38 Species in the Southwest Region (Arizona, New Mexico, Oklahoma, and Texas). [FWS–R2–ES–2018–N006; FXES11130100000C4–189–FF02ENEH00]