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By Todd Isberg
Geographic Range
Milk snakes, Lampropeltis triangulum, have a wider geographical range than most other species of snake. They can be found in the United States almost anywhere east of the Rocky mountains (Audubon 1979).
In Canada, they range from southcentral and southeastern Ontario to southwestern Quebec. They are also found in Mexico and Central America in any non-arid area (Williams 1994). (National Audubon Society Inc, 1979; Williams, 1994)
Habitat
( to 8528 ft)
Milk snakes can thrive in a variety of habitats. They are usually found around coniferous or deciduous forest edges, but they can also be found in tropical hardwood forests, open woodland, dry or wet prairies, savannahs, rocky hillsides, small streams or marshes, and agricultural or suburban areas. These snakes do not fear human proximity but are secretive, so are rarely observed (Vogt 1981). They can be found anywhere from sea level to 8000 feet (Audubon 1979). (National Audubon Society Inc, 1979; Vogt, 1981)
These animals are found in the following types of habitat:
temperate
; terrestrial
.
Terrestrial Biomes:
savanna or grassland
; forest
.
Aquatic Biomes:
rivers and streams.
Other:
suburban
; agricultural
; riparian
.
Physical Description
(13.78 to 68.9 in)
Specimens of L. triangulum have been found in lengths ranging from 35 to 175 cm, with the neotropical populations achieving the greatest lengths. In the United States lengths are most often 60 to 130 cm.
L.triangulum is a very colorful snake. Its body may be gray or tan, having a light Y or V shaped patch on the neck. Black bordered "blotches", brown or rust colored down the sides of the body are common as are red, orange, yellow, or white "blotches" with colorful borders, depending on the subspecies. There are 25 different subspecies known throughout the snake's geographical range, all with slight color variations.
The neck has a light collar with colored, black bordered bands separated by light rings. There are no reported color differences between males and females.
L. triangulum has 19 to 23 rows of smooth scales and a single anal plate (Audubon 1979). (National Audubon Society Inc, 1979)
Some key physical features:
ectothermic
; heterothermic
; bilateral symmetry
.
Sexual dimorphism:
sexes alike.
Reproduction
Milk snakes breed once yearly.
Breeding occurs in spring and early summer, from April through June.
Milk snakes probably mate while still in their hibernacula. They mate in spring before emerging and dispersing to their summer ranges. Mating is probably indiscriminate.
Mating systems:
polygynandrous (promiscuous)
.
Milk snakes lay elliptical eggs in rotting logs or humus in the spring or early summer (Audubon 1979). These eggs are laid in clutch sizes of 2 to 17, usually about 10 (Vogt 1981). Eggs hatch after an incubation period of 28 to 39 days with hatchlings measuring from 14 to 28 cm long upon hatching. The young are always brightly colored, though color dulls as maturity is reached. It takes 3 to 4 years to reach full maturity. (Canadian Amphibian and Reptile Conservation Network, March 1999; National Audubon Society Inc, 1979; Vogt, 1981)
Key reproductive features:
iteroparous
; seasonal breeding
; gonochoric/gonochoristic/dioecious (sexes separate); sexual
; oviparous
.
Milk snake females choose nest sites that are warm and humid. Once the eggs are laid there is no further parental care.
Parental investment:
no parental involvement.
Lifespan/Longevity
Specific data on lifespan is not given, although it is known that one individual caught as an adult lived another 21 years in captivity. (Canadian Amphibian and Reptile Conservation Network, March 1999)
Behavior
A solitary species, L. triangulum is rarely seen in the open during the day, but is often seen crossing roads at night. They usually hide under rotting logs or damp trash, but can be found still active at high temperatures, when other snakes seek refuge from the heat. A favorite hunting ground is around barns or other human locales, lying in wait to feed on the small rodents commonly found in such areas (Vogt 1981).
The only time these snakes are found in groups is during hibernation. Right before and right after hibernation, they can be seen basking in the sun in large groups. (Vogt, 1981)
Key behaviors:
terricolous; diurnal
; nocturnal
; motile
; hibernation
; solitary
.
Communication and Perception
Not much is known about milk snake communication. They use sight, hearing, touch, and smell to perceive their environment. They may use chemical cues to detect sex during their spring mating.
Not much is known about milk snake communication. They use sight, hearing, touch, and smell to perceive their environment.
Communicates with:
chemical
.
Perception channels:
visual
; tactile
; acoustic
; vibrations
; chemical
.
Food Habits
L. triangulum is carnivorous. Adults feed mainly on rodents such as voles, mice, and rats, but will also eat birds, bird eggs, lizards, snake eggs, or other snakes, including venomous species like coral snakes and rattlesnakes. Hatchlings seem to feed mainly on other young snakes. When prey is captured, it is contricted until it suffocates. It is then swallowed whole (Vogt 1981).
Primary Diet:
carnivore
(eats terrestrial vertebrates).
Animal Foods:
birds; mammals; reptiles; eggs.
Predation
- raccoons (Procyon lotor)
- red foxes (Vulpes vulpes)
- striped skunks (Mephitis mephits)
- coyotes (Canis latrans)
Milk snakes are prey for animals such as raccoons, foxes, skunks, and coyotes. When it feels threatened, the snake will vibrate its tail, sounding much like a rattlesnake. This habit may scare away some predators, but it can also get the Milk snake killed by frightened humans who mistake it for a venomous rattlesnake (Audubon 1979). Another adaptation this species has to avoid death by predator is its coloration. Many of the L. triangulum subspecies practice Batesian mimicry. Their color patterns look similar to either those of the venomous copperhead or the coral snake. Again, this adaptation can also mean death for the snake when encountering humans who can't tell the difference. (Canadian Amphibian and Reptile Conservation Network, March 1999; National Audubon Society Inc, 1979)
Anti-predator adaptations::
mimic; aposematic
.
Ecosystem Roles
Milk snakes are important predators of small mammals, birds, and other snakes.
Economic Importance for Humans: Negative
There are no negative affects of milk snakes on humans.
Economic Importance for Humans: Positive
Milk snakes have a close relationship with humans, as they are commonly found in farmland or urban areas. These snakes are beneficial to humans as they feed on rodents that concentrate around barns or trash (Vogt 1981).
Ways that people benefit from these animals:
controls pest population.
Conservation Status
IUCN Red List: [link]:
Not Evaluated.
US Federal List: [link]:
No special status.
CITES: [link]:
No special status.
State of Michigan List: [link]:
No special status.
Though milk snakes are often killed by humans who mistake them for venomous snakes, they are widespread and still considered abundant throughout most of their range. (Canadian Amphibian and Reptile Conservation Network, March 1999)
Other Comments
The milk snake got its name from an Old World folk tale. The tale tells that the snake sucks the milk of nursing mothers and cows until they are dry. Of course we know this to be impossible because the snake is harmless and a human mother or a cow would certainly not allow it. Also, the snake's belly could only hold a few tablespoons of milk (Vogt 1981).
Contributors
Todd Isberg (author), Pima Community College.
Brad Fiero (editor), Pima Community College.




