Queensnake

Description

The queensnake is a slender-bodied, small snake. It is usually between 40 and 60 cm in length, although it can reach a maximum of 90 cm. Queensnakes are typically light to dark brown, though some individuals are grey or olive green in colour. Three slightly darker stripes run down the length of its back, and four dark-coloured stripes down the length of its cream-coloured belly. Although the Queensnake’s belly stripes can become mottled with age, they remain an important identifying feature for this species. The queensnake is the only Ontario snake with stripes down the length of its belly.

The scales of the queensnake are keeled, meaning that each scale has a ridge that runs down its centre. This gives queensnakes the appearance of being rough in texture, rather than smooth and shiny. Snake skin varies in terms of water permeability, depending on its habitat. A desert snake, for example, might have less permeable skin in order to help it retain water. As a semi-aquatic snake, the queensnake’s skin does not need to be adapted against water loss, meaning their skin is unusually permeable. However, this makes them particularly vulnerable to dehydration and heat stress in warmer conditions.

Distribution and Habitat

In Canada, queensnakes are found exclusively in Southern Ontario, west of the Niagara Escarpment and north to the Bruce Peninsula. In the US, they are found throughout the Eastern states, including an isolated population in Arkansas, as far south as Florida.

Queensnakes are semi-aquatic and are almost always found in or around permanent bodies of water. They are most common along rivers with rocky substrates of limestone and slate, which gives them many places to hide and bask. This habitat also supports large populations of crayfish, which make up the vast majority of a queensnake’s diet. The water of their habitat must remain at or above 18^oC during their active season, which in Ontario stretches from mid-May until mid-October. This may be why queensnakes are generally less common in areas where dense canopy cover keeps the water shaded and cool.

In Canada, queensnakes hibernate through the winter in burrows known as hibernacula. Their hibernacula are commonly found underground below the frostline. Queensnakes have been found hibernating communally, although solitary hibernation may also be possible in certain locations.

Reproduction and Development

In the southern portion of their range, queensnakes reach sexual maturity at two to three years of age. However, since the snake’s active season is more limited in Canada, it is likely that individuals in Ontario take an additional year or two to reach maturity.

Queensnakes mate both in autumn and spring. When ready to mate, a male queensnake will approach a female with a courtship display of tongue flicks and head bounces. Female queensnakes give birth between July and September to a litter of 5–23 offspring. Each young snake is between 8 and 14 cm in long.

Diet and Predation

Queensnakes are crayfish specialists, with nearly 100 per cent of their diet consisting of freshly moulted crayfish. The softer shells of these crayfish make them easier prey to capture, as well as a more nutritious meal. Queensnakes are able to locate recently moulted crayfish by detecting chemical compounds released during the crayfish’s moulting cycle. They seek crayfish under water in the rocky crevices where they hide.

Queensnakes generally feed on whichever crayfish species is most abundant in their habitat. In Ontario, scientists believe that they primarily feed on the Northern clearwater crayfish (Orconectes propinquus), which is historically the most common crayfish in their local habitat.

Queensnakes are quite small, which leaves them vulnerable to a variety of predators. This is especially true of young and hibernating snakes, which are predated on by large crayfish and mice. Predators of adult queensnakes likely include American minks, river otters, raccoons, great blue herons and gulls.

Status and Threats

The Committee on the Status of Endangered Wildlife in Canada lists queensnakes as endangered (see also Endangered Animals in Canada). As of 2007, the International Union for Conservation of Nature categorizes queensnakes as “least concern” globally. They note, however, that this species’ status is due to be revaluated and updated.

The queensnake’s highly specific habitat requirements, as well as its limited diet, makes it particularly vulnerable to habitat loss and degradation. Shoreline development and intensive agriculture in and around queensnake habitat are significant threats. Scientists have also raised concerns about the recent decline of the Northern clearwater crayfish (Orconectes propinquus), which may be due in part to competition with the non-native rusty crayfish (Orconectes rusticus). It is currently unknown if queensnakes will be able to switch from hunting clearwater crayfish to the larger rusty crayfish.