The Home Ranges and Wanderings of Snakes

Abstract

NE of the basic instincts of animals is to establish home areas within which the individuals are familiar with their surroundings. As more groups are studied more examples of such relationships appear. Some type of territorial behavior has been found in each major class of vertebrates and in certain invertebrates (Pearse, 1926: 92-93; Heape, 1931: 322-323). The details vary widely with the nature of the animal and its environment, as may be seen from the numerous examples cited by Heape, but the general principle is now so well established that it would be surprising to find unquestionable proof that adult members of any species of terrestrial vertebrate habitually moved about at random. An important distinction is made between the home range and the territory (Burt, 1943). The home range is the area within which the individual ordinarily moves about in the course of its day to day activities. Journeys away from the home range may be made for varying periods of time, or the home range may be shifted, without violation of this concept. The territory is the part of the home range that is defended. It usually includes nesting or food storing sites. The territory is exclusive to an individual or a family of a given species, but much of the home range may be neutral country. Species may have home ranges but no territories. Summaries and references on this subject are given for fishes by Breder (1936), Noble (1938), Noble and Curtis (1939), and Rodeheffer (1941); for birds by Nice (1941), and for mammals by Burt (1943). Frogs and toads of many kinds have resting sites and calling stations to which they habitually return (Noble, 1931: 403-407). Field studies have demonstrated the presence of homing ability in the Salientia, and have shown that while some individuals travel thousands of feet many others remain within a few hundred feet or less of the point of first collection (McAtee, 1921; Breder, Breder and Redmond, 1927; Raney, 1940; Ingram and Raney, 1943). Apparently neither home ranges nor homing have been observed for salamanders, but this may be due to the lack of any satisfactory method of marking these animals for long term studies. Territoriality in lizards is well known (for discussion and references see Evans, 1938; Fitch, 1940; Stebbins, 1944 and 1946; Woodbury and Woodbury, 1945). Various authors have concluded that both aquatic and terrestrial turtles have home ranges to which they will usually attempt to return if displaced. Knowledge of the ranges and travels of turtles has recently been summarized and extended by Cagle (1944). He found no evidence of defensive territorialism. Mcllhenny (1935: 26, 87, 88) states that the alligator usually returns to the same wintering den each year throughout life, and that females frequently use the same nesting site year after year. Territoriality evidently occurs in the alligator, for Mcllhenny remarks that: