Creature Feature: Ringneck snake

To readers with ophidiophobia, or the fear of snakes, Ireland should be high on your vacation destination list. Popular legend attributes the Emerald Isle’s lack of legless reptiles to the actions of St. Patrick. He is said to have banished all snakes from Ireland in the 5th century AD after the serpentine critters attempted to attack him during a 40-day fast. However, fossil records indicate otherwise. Ireland, like many other islands, is void of snakes due to its distance from other major land masses that snakes inhabit. Although land bridges between Ireland and the European continent existed in the past, they were engulfed by rising seas before snakes were able to cross them. As a result, snakes never slithered through the fields of Ireland.

According to legend, St. Patrick drove the snakes out of Ireland in the fifth century AD. The fossil record indicates that snakes never colonized the island before it was cut off from other land masses by the sea [Source]

In contrast, many mainland countries boast a bounty of snakes; the United States, for instance, has over 100 snake species. The state of California alone, which is six times larger than Ireland, is inhabited by over 50 snake species! From boas to sidewinders, striped racers to king snakes, venomous rattlers to harmless gopher snakes, not to mention a whole slew of garter snakes . . . how to choose just one species to feature?

In case you’re hesitant to hop aboard the snakes-are-awesome train, let’s start with a species that is shy, small, non-venomous, and strikingly beautiful: the ringneck or ring-necked snake (Diadophis punctatus). The ringneck snake is one of only a handful of snake species found across nearly all of the continental United States. This makes it a ubiquitous member of American herpetofauna (i.e., the group of animals including reptiles and amphibians). Although you might think their wide geographic range makes them easy to find, ringneck snakes are in fact quite cryptic. This is due, in part, to their nocturnal nature and tendency to hide under logs, rocks, leaf litter, or debris [1].

A ringneck snake found in Florida. Note that this animal was being handled by a trained herpetologist (scientist who studies reptiles and amphibians) for research purposes. Although they are not venomous to human, if you are lucky enough to see one in the wild yourself, please enjoy from a distance and do not attempt to touch it. [Photo taken by: Stevie Kennedy-Gold]

Ringneck snakes are rather wee—some snake lovers might even say adorable—with most growing to around 40 cm, or slightly longer than a foot. Female ringnecks are larger than males, a common pattern among snakes [2]. Sexual size dimorphism, or the difference in body size between different sexes, is influenced by requirements of the female reproductive system to support egg development as well as competition between individuals. For instance, among snakes, it is more common for males to be larger than females in species where males must physically fight for access to female mates [2].

The prairie ringneck snake (Diadophis punctatus arnyi), one of more than a dozen subspecies, has a black dorsal side and bright yellow to red underside with prominent block spots. [Photo taken by: Peter Paplanus, Source]

The scientific name for ringneck snakes refers to the characteristic band around their neck and their spotted underside (Diadophis from the Greek words diadem meaning “headband” and ophios meaning “serpent”; punctatus from the Latin punctum meaning “holes” or “spots”). The bodies of ringneck snakes are predominantly black, brown, or green-grey, but their ventrum (belly) is bright yellow to orange-red with scattered darker spots or bands. Like many broadly distributed species, they show geographic differences in their appearance and behavior. Ringnecks are divided into multiple subspecies that differ in their geographic distribution, habitat preference, size, and appearance, and each subspecies has a different variation on the common color and spotting pattern [3].

Ringneck snakes eat earthworms, small insects, and salamanders, and they are preyed on by birds, small mammals, and other snakes. One interesting ringneck behavior is their defensive tail-coiling posture. When threatened by an approaching predator, ringneck snakes will coil their tail and display their brightly-colored ventral side (see picture below). They may also do this when approached by humans—remember, snakes see you as a predator, so they are much more frightened of you than you are of them! The tail-coiling display is thought to be an aposematic display, a conspicuous signal to predators warning them not to attack.

A Pacific ringneck snake (Diadophis punctatus amabilis) exposes its bright red underside in a defensive tail coiling display. [Photo taken by: J. Maughn, Source]

When it comes time to breed in spring, the romantic acts of ringnecks and other snakes are a little unorthodox. During copulation, the male snake bites the female around the neck (lizards actually do this too); without arms, they have to hold on somehow! Females may mate with multiple males before laying a clutch of 3–10 eggs, which develop for around two months. The sweet baby snakelings hatch in early fall, at only 8–11 cm long (about as long as your pointer finger) [1].

Much like humans sloughing off skin cells on a daily basis, reptiles also routinely shed their skin, a process called ecdysis. Unlike us, snakes typically do this in one go. Ecdysis allows snakes and other reptiles to continue growing and remove parasites that latch onto their body. Snakes on the brink of shedding may be extra crabby; herpetologists refer to individuals in this state as being “in the blue” or “in the grey”. This is because snakes lack eyelids and instead possess a single scale that covers their eye, which begins to push away from the eye as a snake prepares to shed. When this happens, the snake’s eye has a blue or grey appearance and its vision is impaired. With limited vision, the animals can be feistier than normal and, though usually docile, they may be more keen to strike. Although we should always be cautious and keep our distance around wild animals, snakes “in the blue” should be given an extra wide berth. As mentioned earlier, ringneck snakes are rather reclusive and shy, often hiding during the day in their forest, grassland, and marsh habitats. It can be challenging for researchers to study cryptic species such as ringnecks because it is difficult to accurately map their distribution and gather basic information about their behavior. One solution to this problem is citizen science! Platforms such as iNaturalist, one of the largest citizen science projects in the world, allow anyone—from students to casual nature lovers to urban bird watchers—to record and get help identifying plants and animals they encounter in the wild. Citizen scientists have logged over 6,000 sightings of ringneck snakes on iNaturalist. You can download the iNaturalist app on your smart phone and begin logging your own encounters with wildlife!

Location of ringneck snakes sightings recorded by citizen scientists on iNaturalist.

Hopefully you are now convinced that snakes, like the ringneck, are not only scaly and slithery but fascinating and beautiful creatures. It was a quirk of geography, and not St. Patrick, that deprived the Emerald Isle of these infamous animals, but perhaps even the celebrated saint would not have been so zealous about banishing snakes from Ireland had he gotten to know them a bit better.


Jessica Schaefer is a PhD student in the Animal Behavior Graduate Group at UC Davis. She studies the behavioral ecology and mating systems of species from limpets to lizards to birds.

Stevie Kennedy-Gold is the collection manager for the Section of Amphibians and Reptiles at the Carnegie Museum of Natural History. She loves the desert and “herping”, and her research focuses on ecology of reptiles, including the effects of competition between species on their behavior.


References:

  1. Yung, J. (2000). Diadophis punctatus, Animal Diversity Web. Accessed March 12, 2020 at https://animaldiversity.org/accounts/Diadophis_punctatus/.
  2. Shine, R. (1994). Sexual size dimorphism in snakes revisited. Copeia, 2, 326–346.
  3. Uetz, P. and Hallermann, J. Diadophis punctatus (Linnaeus, 1776), Reptile Database. Accessed March 12, 2020 at http://reptile-database.reptarium.cz/species?genus=Diadophis&species=punctatus.

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