Crotalus willardi

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Crotalus willardi
Arizona ridgenosed rattlesnake closeup.jpg
Scientific classification Red Pencil Icon.png
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Order: Squamata
Suborder: Serpentes
Family: Viperidae
Genus: Crotalus
Species:
C. willardi
Binomial name
Crotalus willardi
Meek, 1905
Crotalus willardi distribution.png
Synonyms [2] [3]
  • Crotalus willardi
    Meek, 1905
  • Crotalus willardi willardi
    Klauber, 1949
Common names: ridge-nosed rattlesnake, Willard's rattlesnake, Willard's rattler [4]

Crotalus willardi is a venomous pit viper species found in the southwestern United States and Mexico. This snake is found mainly in the "sky island" region. [5] The IUCN reports this snake's conservation status as being of Least Concern. [6] It is the official state reptile of Arizona. [7]

Contents

Etymology

The specific name, willardi, is in honor of its discoverer, "Professor" Frank Cottle Willard, a businessman from Tombstone, Arizona. [8] [9]

Taxonomy

Originally described in 1905, Crotalus willardi is the most recent rattlesnake species to be discovered in the United States. Five subspecies are currently recognized, including the nominate subspecies, Crotalus willardi willardi, described here. [10] C. w. willardi is commonly known as the Arizona ridge-nosed rattlesnake, and is the state reptile of Arizona.

Description

Crotalus willardi is a rather small rattlesnake with all subspecies measuring one to two feet (30–60 cm) in length. Color patterns are generally a dark brown base with pale or white horizontal striping, but vary slightly among subspecies. The distinctive ridges along each side of its nose, which are a series of upturned scales, are unique to this species and are the origin of one of its common names, ridge-nosed rattlesnake.

Habitat

C. willardi is rarely found outside habitats at high elevation. Wooded mountain ranges, primarily in the southwest, are where this reclusive species is found. Each subspecies’ range is limited to select mountain ranges, making human encounters rare events.

Conservation status

The species C. willardi is classified as Least Concern on the IUCN Red List of Threatened Species (v3.1, 2001). [1] Species are listed as such due to their wide distribution, presumed large population, or because they are unlikely to be declining fast enough to qualify for listing in a more threatened category. The population trend was stable when assessed in 2007. [11]

Although four of the five subspecies are secure, the New Mexico ridge-nosed rattlesnake (C. w. obscurus) is an endangered subspecies and listed as threatened by the US Fish and Wildlife Service. Remaining populations are scattered throughout New Mexico, Arizona and the northern part of Mexico. Habitat destruction is the cause of declining numbers, but critical habitat designations (recovery measures) have been proposed.

Behavior and diet

Rattlesnakes are primarily ambush hunters; they coil and lie waiting for prey to approach within striking distance. The diet of C. willardi includes small mammals, lizards, birds, and large centipedes. The young feed primarily on large centipedes (Scolopendra spp.) and lizards, whereas adults feed primarily on mammals and birds. [12]

Reproduction

Like other rattlesnakes, C. willardi is ovoviviparous, meaning it gives birth and does not lay eggs. Contrasting with viviparous animals, the young still develop within an egg inside the female snake until their time of birth. Copulation occurs from late summer to early fall, and gestation lasts about four to five months. Females give birth to two to 9 (average five) young in late July or August. Both sexes appear to reach reproductive maturity around 400 mm (16 in) in body (snout to vent) length. Although captive snakes have reproduced annually, wild females probably reproduce every second or third year. [13]

Venom

Due to the generally small size of C. willardi, venom discharge yields are low; thus, the largely hemotoxic venom is not as life-threatening as that of other rattlesnakes. No documented deaths have been caused by ridge-nosed rattlesnakes, but pain and discomfort can still result from a rare bite.

Subspecies

Subspecies [10] Taxon author [10] Common name [14] Geographic range [15] [16]
C. w. amabilis Anderson, 1962Del Nido ridge-nosed rattlesnakeMexico in north-central Chihuahua
C. w. meridionalis Klauber, 1949Southern ridge-nosed rattlesnakeMexico in southern Durango and southwestern Zacatecas
C. w. obscurus Harris & Simmons, 1974New Mexico ridge-nosed rattlesnakeThe US in extreme southeastern Arizona and extreme southwestern New Mexico, Mexico in extreme northwestern Chihuahua and extreme northeastern Sonora
C. w. silus Klauber, 1949Chihuahuan ridge-nosed rattlesnakeWestern Chihuahua and eastern Sonora
C. w. willardi Meek, 1905Arizona ridge-nosed rattlesnakeSoutheastern Arizona, and northern Sonora

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References

  1. 1 2 Hammerson GA, Vazquez Díaz J, Quintero Díaz GE (2007). "Crotalus willardi". IUCN Red List of Threatened Species . IUCN. 2007: e.T62253A12584209. doi: 10.2305/IUCN.UK.2007.RLTS.T62253A12584209.en .
  2. McDiarmid RW, Campbell JA, Touré T (1999). Snake Species of the World: A Taxonomic and Geographic Reference, Volume 1. Washington, District of Columbia: Herpetologists' League. 511 pp. ISBN   1-893777-00-6 (series). ISBN   1-893777-01-4 (volume).
  3. "Crotalus willardi ". The Reptile Database. www.reptile-database.org.
  4. Wright AH, Wright AA (1957). Handbook of Snakes of the United States and Canada. Ithaca and London: Comstock Publishing Associates. 1,105 pp. (in 2 volumes). (7th printing, 1985, ISBN   0-8014-0463-0). (Crotalus willardi, pp. 1034-1037, Figures 294-295 + Map 67 on p. 951). .
  5. Brennan, Thomas (2008). "RIDGE-NOSED RATTLESNAKE Crotalus willardi". Retrieved 16 May 2019. http://www.reptilesofaz.org/Snakes-Subpages/h-c-willardi.html
  6. Hammerson, G.A., Vazquez Díaz, J. & Quintero Díaz, G.E. 2007. Crotalus willardi. The IUCN Red List of Threatened Species 2007: e.T62253A12584209. http://dx.doi.org/10.2305/IUCN.UK.2007.RLTS.T62253A12584209.en. Downloaded on 16 May 2019.
  7. Arizona Rattlesnakes: Rattlesnake Facts, Arizona Game and Fish Department , retrieved 2019-05-16
  8. Beltz, Ellin (2006). Biographies of People Honored in the Names of the Reptiles and Amphibians of North America
  9. Beolens, Bo; Watkins, Michael; Grayson, Michael (2011). The Eponym Dictionary of Reptiles. Baltimore: Johns Hopkins UNiversity Press. xiii + 296 pp. ISBN   978-1-4214-0135-5. (Crotalus willardi, p. 286).
  10. 1 2 3 "Crotalus willardi ". Integrated Taxonomic Information System . Retrieved 16 May 2007.
  11. 2001 Categories & Criteria (version 3.1) at the IUCN Red List . Accessed 13 September 2007.
  12. Holycross et al., 2002.
  13. Holycross & Goldberg, 2001.
  14. Mehrtens JM (1987). Living Snakes of the World in Color. New York: Sterling Publishers. 480 pp. ISBN   0-8069-6460-X.
  15. Campbell JA, Lamar WW (2004). The Venomous Reptiles of the Western Hemisphere. 2 volumes. Ithaca and London: Comstock Publishing Associates. 870 pp., 1500 plates. ISBN   0-8014-4141-2.
  16. Klauber LM (1997). Rattlesnakes: Their Habitats, Life Histories, and Influence on Mankind. Second Edition. (2 volumes). (Reprint, Berkeley: University of California Press. ISBN   0-520-21056-5).

Further reading