A radiotelemetric study of movements and shelter-site selection by free-ranging brownsnakes (Pseudonaja textilis, Elapidae)

Radio tracking of 40 free-ranging eastern brownsnakes (Pseudonaja textilis) in an agricultural landscape in southeastern Australia clarified the spatial ecology of these highly venomous animals. Most snakes over-wintered in burrows within a small area on the bank of an irrigation canal, dispersing into agricultural land during the warmer months. The snakes sheltered overnight in burrows or soil cracks, reusing the same retreat on successive nights and moving about to forage during the day. Successive shelter-sites averaged 152 m apart, and the snakes moved between them on average every six days. Home ranges of adult snakes were small (average MCP = 5.8 ha), and did not differ significantly between years with varying prey abundance. Movement patterns depended upon the snakes' sex, reproductive condition and body size. Adult males moved earlier in spring than did the (smaller) adult females, moved further and more often, and had larger home ranges. Home range size increased with body size in males, but not in females. Shelter-site selection was influenced by the location of potential prey (House Mice, Mus domesticus) and the location of other snakes. When radio-tracked snakes moved, they generally traveled from areas of lower to higher prey abundance (as determined by mammal-trapping). Throughout most of the year, adult male snakes were avoided by females and by other males. Adult males rarely cohabited with other snakes, and their arrival at an occupied burrow generally induced the resident snake to depart. Our study thus provides the first strong evidence that agonistic interactions can influence the spatial ecology of snakes.