Tiger Keelback (Rhabdophis tigrinus) — identification, habitat & look-alikes

The tiger keelback is a Japanese snake that is venomous in two ways: it has rear fangs that can deliver a dangerous bite, and it stores poison taken from the toads it eats in glands on its neck. It isn't found in the US; it lives on Japan's main islands of Honshu, Shikoku, and Kyushu.

Appearance

Appearance: Usually 2–4 ft (60–120 cm) long. It is olive green with black and bright orange-red blotches along the front part of the body and a yellow band on the neck. Colors vary by region in Japan, and some western populations include bluish snakes.

Where it lives

Typical habitats: wetlands
streamsides
rice paddies
Range: Japan's Honshu, Shikoku, and Kyushu and nearby islands such as Yakushima and Tanegashima; snakes in Taiwan are also often counted as this species. It does not occur in the US.
Preferred conditions: Usually stays near water, where frogs are plentiful, and it swims well. In Japan it is common in rural rice-farming areas but rare in cities.

Behavior

Diet: Mainly frogs and toads, plus salamanders, skinks, and small fish such as loaches.
Activity: When threatened in cool weather, it tends to flatten its neck and body and stay still, showing off its neck glands; when warm, it is more likely to flee.

Life cycle

Breeding season: Mates in fall; females lay eggs the following July.
Reproduction: Mothers can pass stored toad toxins into their eggs, so newly hatched young are protected too.
Clutch size: 2–43 eggs

Cautions

Cautions: Its fangs sit at the back of the mouth, so short bites may inject little or no venom, but a deep bite can cause serious bleeding problems, and deaths have been recorded in Japan. Pressing on its neck can make the neck glands spray toad-derived toxins, which can injure the eyes.

Name and classification

About the name: The snakes of Korea, mainland China, and the Russian Far East were long treated as a subspecies, R. t. lateralis. Many recent authors now call them a separate species, Rhabdophis lateralis, because they are genetically distinct, though some sources still lump them together. The Taiwan population is often called R. t. formosanus.