Reptiles & Amphibians of France - Ladder snake, Rhinechis scalaris

Ladder snake, Rhinechis scalaris
(Schinz, 1822)

History and origin
The Ladder snake was first described by Schinz in 1822. Formally Elaphe scalaris. Elaphe meaning ratsnake, scalaris means ladder, ladder ratsnake, now named Rhinechis scalaris, the origin of the name Rhinechis is uncertain but may be made of two words, the first meaning 'nose' and second word meaning 'sharp' because of their pointed snout.

Characteristics
Juveniles are characterised by a ladder pattern and older adults have two dark parallel lines running down the back.

Description
=Size=
They hatch at around 30 cm, averaging about 100 cm growing up to 160 cm.
=Morphology=
They are slim and elegant. Their nose appears lightly upturned.
=Patterns & colours=
Juveniles are creamy or whitish with a vivid dark (usually black) ladder pattern on the back. Their belly is creamy as well. As they grow, the cross bands that once formed the ladder pattern by linking two parallel lines on the back, start to fade until they disappear. They become adults and their background colour has also matured into a light brown colour, their belly is now more yellow. They have a dark line, from the eye downwards onto the lips. A dark line is also common from the eye backwards to the neck.

Geographical range
Found in western Europe: Portugal, Spain (except northern coast) and Mediterranean France. There is a small area in Italy next to the French border where it is said to occur, but this has been questioned. Also on Menorca.

Subspecies
None described

Sexual differences
Females and larger then the males, especially in late spring when they carry their eggs.

Seasonal variations
Females are larger in spring due to their eggs.

Diet
Like all rat snakes (Elaphe s.l.), its main food source are rodents. They also eat lizards and sometimes bird eggs as well as birds. They constrict their prey.

Defensive habits
They are not as shy and fast moving as sympatric snake species. It is possible to get very close to this snake without it fleeing, their usual defense consists of intimidation, hissing, inflating itself and sometimes opening their mouth and occasionally biting.

Reproduction
Breeding occurs when the snakes wake up from hibernation in spring, a week after, they are all looking for each other and mating begins. After only a few weeks about 12 eggs are laid (extremes are from 4 to 15 eggs) in a moist, warm spot, usually under hey piles, in rotting wood piles and other places of this kind. The eggs incubate for around 10 weeks before hatching.

Sexual maturity, life span
The average life span of Rhinechis scalaris is about 20 years. They reach sexual maturity in their fifth year, males usually mature sooner.

Habits
They enjoy sun-bathing can climb against steep structures. They are the most tolerant French snake species towards heat, sometimes seen in mid-summer at the hottest hours.

Venom
This is a non-venomous snake.

Habitat
They live in dry, open, often rocky areas, rich in stone formations making hiding easier, there is usually dense vegetation nearby.

Predators
They have many predators, mainly small mammals (as juveniles), birds of prey etc.