Reptilia · Squamata
Crotalus willardiMeek, 1905
willardi
Photograph by ryan_potts, CC BY-SA, via iNaturalist
A ground-dwelling, active by day or night, meat-eating snake from the Nearctic region, reaching 670 mm nose to tail.
Also called New Mexican Ridge-nosed Rattlesnake, Ridge-nosed Rattlesnake.
Reptilia › Squamata › Viperidae › Crotalus
- Grows to
- 670mm
- greatest recorded
- Eats
- Carnivorous
- Active
- Cathemeral
- Lives up to
- 21.3years
Longer than only 28% of all vipers anyone has measured.
The bar is the rank itself: its length is the share of the family this animal exceeds. The chart below is the family’s real spread, on a logarithmic scale because body length here runs from 280 to 3,900 mm. The solid rule is this animal. Every bar is a count of real species, and nothing on this figure is estimated.
What is known
36 sourced facts, each taken from a named scientific dataset. How to read these.
Cited from a dataset unless a row is marked otherwise.
Standing in the world
- Still living
- Extant
- Conservation status
- Least Concern
- Status assessed · the year the Red List last looked
- 2007
- Population trend
- Stable
The animal itself
- Limbs
- None
- Venomous
- Yes
- Fangs
- At the front of the mouth
- Longest recorded life
- 21.3years
- Body temperature when active · measured in the wild
- 20.11°C68 °F
- Body temp in the wild · mean, when active
- 17.5–30°C64–86 °F
Stark et al. 2020
mean body temperature of active individuals in nature
body temperature of active animals in nature
Size
- Length nose to tail · greatest recorded
- 670mm2 ft 2 in
- Body mass · greatestcomputed
- 162.5g5.7 oz
- Body mass · a typical adult
- 100g3.5 oz
- Body mass at hatchingmeasured
- 5.5g0.19 oz
snakes only in this source
computed from length by a family-level allometric equation, not weighed
AnAge rates this record "acceptable"
How it lives
- Dietcomputed
- Carnivorous
- How it hunts
- Mixed
- Active
- Cathemeral
- Where it lives
- Terrestrial
- Habitat
- Forest, Rocky, Shrubland
- Biome
- Tropical & Subtropical Coniferous Forests
- Region
- Nearctic
- Mainland or island
- Mainland
- Elevation · above sea level
- 1470–2800m
- Range size
- 201,277km²
no actual data but can be imputed as carnivorous like all snakes
Feldman 2015
Stark et al. 2018
Scharf et al. 2015
1500-2300 rarely 2800 (O'Shea 2018), 1475-2800 (Feldman 2015)
Breeding
- Reproduction
- Viviparous
- Average clutch
- 5.4eggs
- Eggs or young per clutch
- 2–9eggs
- Mean clutch
- 5.8eggs
- Clutches in a year
- 0.5per year
Feldman et al. 2015, Meiri et al. 2019
mean 5.8 (Meiri et al. 2019), 4-8 (O'Shea 2011), 2-9 (O'Shea 2018)
Naming and history
- Suborder
- Serpentes
- Infraorder
- Alethinophidia
- Subspecies
- Crotalus willardi amabilis ANDERSON 1962 Crotalus willardi meridionalis KLAUBER 1949 Crotalus willardi obscurus HARRIS 1974 Crotalus willardi silus KLAUBER 1949 Crotalus willardi willardi MEEK 1905
- Described by
- Meek
- Moved to another genus · since it was first described
- No
- Described in
- 1905
- Type locality
- USA
Keeping one
2 ft 2 in × 13 in × 20 in(67 × 34 × 50 cm)
Minimum length × width × height, for one animal. Bigger is always better.
The standard sizes snakes as a fraction of total length: 1 × 0.5 × 0.75.
Mindestanforderungen an die Haltung von Reptilien (Sachverständigengutachten), German Federal Ministry for Nutrition, Agriculture and Forestry, Animal Welfare Division, 10 January 1997. The standard states these floor areas are recommendations rather than binding limits.
From this animal’s own total length of 2 ft 2 in (670 mm), at 1 × 0.5 × 0.75 times it, following the German federal welfare standard — how this is worked out.
Active animals measured in the wild averaged 68 °F (20.1 °C).
Mean body temperature of active individuals measured in nature. A measurement of the animal, not a setting for a thermostat.
Feeding
A prey item should be between the same width as the widest part of the snake's body and about 1.5 times that width.
Widely used across snake husbandry references. An alternative formulation gives prey at 10-15% of the snake's body mass. This is established practice, not a measurement.
18kJ per day
Worked out for an animal of 163 g, the heaviest recorded for willardi — so it is the top of the range, not a figure for a particular animal. Weigh yours and the number will be lower.
An upper estimate, not a feeding target, and not veterinary advice. The equation covers only what an animal burns staying alive, so a growing, gravid or recovering animal needs more — and it was measured on wild animals, which move far more than one in an enclosure. Body condition and a vet who knows the species are what a feeding decision should rest on. Where this comes from.
What nobody knows
These are not gaps in our research. No scientific dataset records them for this species — and saying so is information you cannot get from a reference that simply leaves a field out.
- — Length snout to vent · greatest recorded
- — Length snout to vent · adult female mean
- — Length snout to vent · adult male mean
- — Length snout to vent · adult mean
- — Female length · mean, nose to tail
- — Length nose to tail · adult male mean
- — Length nose to tail · adult mean
- — Largest female · snout to vent
- — Largest male · snout to vent
- — Largest female · shell length
- — Largest male · shell length
- — Hatchling length · snout to vent
- — Hatchling length · nose to tail
- — Largest juvenile · snout to vent
- — Largest juvenile · shell length
- — Egg length
- — Egg width
- — Body mass · adult female, mean
- — Preferred body temperature · chosen in a laboratory gradient
- — Eats arthropods
- — Eats vertebrates
- — Eats plant matter
- — How the young develop
- — Gestation or incubation
- — Clutches a year · fewest
- — Clutches a year · most
- — First breeds from · youngest recorded
- — First breeds by · oldest recorded
- — Hatchling length · smallest recorded
- — Hatchling length · largest recorded
- — Age at first breeding · female
- — Mature from · youngest recorded
- — Mature by · oldest recorded
- — Size at maturity · smallest recorded
- — Size at maturity · largest recorded
- — Colour on the back
- — Pattern on the back
- — Pupil
- — Sex decided by
- — Red List criteria
- — Active season · shortest recorded
- — Active season · longest recorded
- — Density · lowest recorded
- — Density · highest recorded
- — Home range · largest recorded
- — Active in
Others in Viperidae
Take this data
Everything on this page is available as data under CC BY 4.0 — use it freely, credit it, no permission needed.
This species as JSON · the whole dataset
Cite this page
The Reptile & Amphibian Encyclopedia (2026). Crotalus willardi. Retrieved 2026-09-08, from https://www.allanglescreatures.com/species/crotalus-willardi
@misc{crotalus_willardi_2026,
title = {Crotalus willardi},
author = {{The Reptile & Amphibian Encyclopedia}},
year = {2026},
url = {https://www.allanglescreatures.com/species/crotalus-willardi}
}Sources
- Meiri, S. (2024). SquamBase — a database of squamate (Reptilia: Squamata) traits. Global Ecology and Biogeography. Public domain (CC0).
- Oskyrko, O. et al. (2024). ReptTraits: a comprehensive dataset of ecological traits in reptiles. Scientific Data. Used under CC BY 4.0.
- Catalogue of Life (dataset 3LR), used under CC BY.
- AnAge, Human Ageing Genomic Resources (de Magalhães et al.), used under CC BY 3.0.