Traditionally reptiles have been defined as amniote vertebrates (animals whose embryos are surrounded by an amniotic membrane, and possess a backbone) that are ectothermic. They have scaly body coverings and (mostly) lay eggs on land. This definition includes turtles, crocodilians, the Tuatara from New Zealand, and squamates. Squamates include snakes, lizards, and amphisbaenians. These groups are classified together because all are characterized by the criteria mentioned above. However, the current and most widely accepted method of classifying living things – cladistics – is considered to be the most objective as it considers an organism’s evolutionary history. Using this type of classification, birds would be included within the class Reptilia. Furthermore, recent classifications have removed turtles from the reptiles and placed them in the class Chelonia. Although there have been changes to classifications, for the sake of simplicity we will refer to turtles and squamates (lizards and snakes) as reptiles on this website. British Columbia has relatively few species of reptiles: only one native turtle, two native lizards, and nine snake species. This is because much of the province lacks a warm season long enough to allow ectothermic vertebrates to survive. However, there are significant reptile populations in the Southern Interior, where the warm, dry valleys are contiguous with the reptile-rich desert of the western United States. Because of their protective scales and their reproductive strategies of laying shelled eggs or bearing live young, reptiles are generally less dependent upon moisture and water, allowing them to exploit more arid environments. Key habitat needs for reptiles are warmth, habitat complexity, and habitat connectivity.