Milk Snake (S/F)

The milk snake (Lampropeltis triangulum) is a species of nonvenomous snake belonging to the family Colubridae which can be found throughout the warmer parts of the Americas. The milk snake is crepuscular, especially during the summer months when the heat of the day is often beyond its tolerance. The name “milk snake” comes from the urban legend that they drink the milk of cows. It is not anatomically capable of suckling from a cow’s udder, however; the myth likely originates from the fact that milk snakes will frequently take advantage of barns for habitat. Barns provide cool, shady environments where rodents may be found, and so are ideal places for the snake to live.

There are twenty-four subspecies of milk snake, at least one of which inhabits Isla Sorna:

  • Lampropeltis triangulum abnorma: Guatemalan milk snake
  • Lampropeltis triangulum amaura: Louisiana milk snake
  • Lampropeltis triangulum andesiana: Andean milk snake
  • Lampropeltis triangulum annulata: Mexican milk snake
  • Lampropeltis triangulum arcifera: Jalisco milk snake
  • Lampropeltis triangulum blanchardi: Blanchard’s milk snake
  • Lampropeltis triangulum campbelli: Pueblan milk snake
  • Lampropeltis triangulum celaenops: New Mexico milk snake
  • Lampropeltis triangulum conanti: Conant’s milk snake
  • Lampropeltis triangulum dixoni: Dixon’s milk snake
  • Lampropeltis triangulum gaigeae: Black milk snake
  • Lampropeltis triangulum gentilis: Central Plains milk snake
  • Lampropeltis triangulum hondurensis: Honduran milk snake
  • Lampropeltis triangulum micropholis: Ecuadorian milk snake
  • Lampropeltis triangulum multistriata: Pale milk snake
  • Lampropeltis triangulum nelsoni: Nelson’s milk snake
  • Lampropeltis triangulum oligozona: Pacific Central American milk snake
  • Lampropeltis triangulum polyzona: Atlantic Central American milk snake
  • Lampropeltis triangulum sinaloae: Sinaloan milk snake
  • Lampropeltis triangulum smithi: Smith’s milk snake
  • Lampropeltis triangulum stuarti: Stuart’s milk snake
  • Lampropeltis triangulum syspila: Red milk snake
  • Lampropeltis triangulum taylori: Utah milk snake
  • Lampropeltis triangulum triangulum: Eastern milk snake

Thus far, only one individual has been observed on Isla Sorna, and its entire body was not visible at the time; only its tail was recorded. Based on its locality, it is most likely one of the following: the Guatemalan, black, Ecuadorian, Pacific Central American, or Stuart’s milk snake. The tail coloration that has been observed suggests that the individual in question is probably an Ecuadorian, Pacific Central American, or Stuart’s milk snake; however, coloration between the subspecies can vary, and tricolor varieties are far from unknown in subspecies that are usually patterned differently in the wild.

Description

While there are twenty-four subspecies of milk snake, this particular one is identified by a base red color with black and yellow rings or bands. The yellow may be replaced by deep orange in some specimens, referred to as a “tangerine phase” snake. In some of the subspecies, the tail region may lack white or yellow bands; if a snake whose subspecies normally lacks said bands does possess them, it is referred to as a “hypomelanistic tricolor” snake. For example, the black milk snake is melanistic in the wild, having an almost completely black body. However, some breeds and populations of this subspecies can resemble the one witnessed on Isla Sorna in 1997, and these would be hypomelanistic tricolors.

Size varies based on subspecies, but in general, milk snakes grow between 20 and 60 inches (51 to 152 centimeters) long. Its body is covered in smooth, shiny scales. Many subspecies, including the one seen on Isla Sorna, exhibit a form of Batesian mimicry: they have evolved to resemble the highly venomous coral snake, which inhabits Latin America. This mimicry is designed to deter predators, which may mistake the nonvenomous milk snake for the coral snake. In milk snakes, the color patterning often appears as red, black, yellow, black, red; in some, the pattern has white instead of red. However, many subspecies exhibit wildly different color patterns and some are not mimics of any species of coral snake at all. Most do mimic some species of venomous snake, but the traditional means by which milk snakes can be told apart from the venomous species they mimic are not always reliable.

Growth

Hatchlings are approximately eight inches long, and are darker-colored than the adults.

The lifespan of most milk snake subspecies in the wild is around twelve years; in captivity, they have been known to live as long as twenty-one years.

Sexual Dimorphism

Male and female milk snakes grow to the same length and have the same range of color patterns; as of such, there is no external sexual dimorphism.

Habitat
Preferred Habitat

The milk snake prefers to inhabit warm environments, but is tolerant of cooler climates. It may be found in forests and other sheltered areas where shade and food are easy to come by; to avoid danger, it often hides in leaf litter, which is another feature that draws it to forests.

Some of the subspecies not found in Costa Rica are known to inhabit prairies, rocky deserts, and other such open areas.

Isla Nublar

The milk snake is not known from Isla Nublar, though its presence on Isla Sorna means that it likely did exist here. If any inhabited the island, they may have become extinct during the June 23, 2018 volcanic eruption of Mount Sibo.

Isla Sorna

It is known to inhabit the central region of the island near the Workers’ Village as of May 1997. Based on its habitat needs, it could theoretically live over much of Isla Sorna. Much of the island consists of moist forests and there are few very tall mountains, so the only areas where this species would not be found would be the open grasslands and plains.

Known (red) and hypothetical (purple) range of L. triangulum on Isla Sorna, circa 1997
Other

Between its known subspecies, the milk snake can be found as far north as Maine and British Columbia, all through the United States including Florida, the Caribbean, and as far south as the northern countries in South America. The greatest number of subspecies can be found in Mexico.

Behavior and Ecology
Daily Activity

These snakes are crepuscular, emerging at dawn and dusk to feed on small animals. One on Isla Sorna has been observed late at night, where it was resting in a small cave before being disturbed.

Diet and Feeding Behavior

Milk snakes generally prey on small rodents, amphibians, and reptiles, including lizards and snakes; they may prey on venomous snakes without any apparent difficulty and are also known to be cannibalistic. Small birds are also potential prey. They may also eat eggs. The juveniles, before they are large enough to kill vertebrate animals, feed on invertebrates such as slugs, insects, and worms.

Prey is killed by constriction, rather than biting; milk snakes are nonvenomous.

Social Behavior

Due to their cannibalistic tendencies, all milk snakes are solitary except when mating.

Reproduction

The milk snake is sexually mature at 18 months, and may lay three to eighteen eggs at a time. Eggs are laid starting in early June, and incubate for two months. They hatch in August or September. As with most snakes, the milk snake shows no parental care, and may even view its young as potential food if they do not vacate the area quickly enough.

Vocalizations

Milk snakes are not known to vocalize, and communicate mainly by scent. As they are not social, their main forms of communication are to attract mates.

Ecological Interactions

They are not venomous, and will rarely bite if threatened; they usually employ other defense mechanisms first, such as attempting to flee or discharging a foul smell. Due to its small size, this snake would probably not be a threat to any dinosaurs, and may instead be preyed upon by some carnivorous species such as Velociraptor and Compsognathus, which are found in the same habitat.

To avoid being eaten, most milk snake subspecies employ Batesian mimicry, which means they have evolved to resemble a threatening species. Many resemble coral snakes, which are highly venomous; this deters predators from attacking, as the predators are unwilling to take the risk of finding out whether this snake is venomous or not. Even so, when disturbed by humans or other animals, this reptile prefers to flee. This is likely what killed Dr. Robert Burke during the 1997 Isla Sorna incident; having been disturbed in the middle of the night when it would be sleeping, a milk snake fled into the nearest shelter it could find, which happened to be Dr. Burke’s shirt collar. This frightened the paleontologist to his death as he stumbled into the reach of a tyrannosaur.

While the snake was almost certainly consumed along with Dr. Burke during the incident, it is unlikely that an adult female Tyrannosaurus rex under normal conditions would prey on such a small animal intentionally.

Milk snakes prey on numerous small animals, and some have a resistance to the venom of other snakes. This enables them to prey on venomous snakes, as well as small animals such as insects, worms, slugs, lizards, snakes, frogs, rodents, and birds. They may also eat the eggs of small animals. All of these activities keep in check the populations of other animals in the ecosystem.

Interactions with Humans

In real life, Honduran milk snakes are docile and skittish, biting only when cornered. During the 1997 Isla Sorna incident, one hid when disturbed by the InGen Harvester party. Unfortunately, its hiding place was the shirt collar of Dr. Robert Burke, whose fear of snakes led to him stumbling into the reach of a tyrannosaur. This led to the death of Dr. Burke, and presumably the snake as well.