Habitat selection in an Ontario population of the snake, Elaphe obsoleta.

During the bird breeding season black rat snakes showed a preference for field habitat although in both the field and deciduous forest the snake points were significantly clustered along the habitat interface. Following the bird breeding season, field and deciduous forests habitats were used in proportion to their availability and the preference for the ecotone was no longer found in field samples. There was limited evidence of non-random habitat use within habitats with regard to both plant species composition and vegetation structure. Inactive sites were diverse but all were located on the forest-field interface, had open exposure to direct sun and provided shelter for the snakes. Ideal habitat for black rat snakes thus appears to be a small scale mosaic of field and forest. Their disappearance from other parts of their range in Canada may be related to the disappearance of such mosaics due to land clearing for agriculture. -from Authors