Responses of free-ranging brownsnakes (Pseudonaja textilis : Elapidae) to encounters with humans

Abstract

Eastern brownsnakes (Pseudonaja textilis) are large (to 2 m), slender, dangerously venomous elapid snakes that cause significant human mortality. We recorded the responses of free-ranging brownsnakes to 455 close encounters with a human observer, using 40 snakes implanted with miniature radio-transmitters, plus encounters with non-telemetered animals. Our study area (near Leeton in south-eastern Australia) is typical of many of the agricultural landscapes occupied by P. textilis. Contrary to public opinion, the snakes were rarely aggressive. About half of the encounters resulted in the snake retreating, and on most other occasions they relied on crypsis. Snakes advanced towards the observer on only 12 occasions (<3% of encounters) during initial approach, and only three of these advances were offensive. The snakes’ responses to an approach depended on the observer’s appearance (e.g. snakes were more likely to ignore an observer wearing light rather than dark shades of clothing) and behaviour (e.g. snakes were more likely to advance if approached rapidly, and touched immediately). Snakes were more likely to retreat if they were sub-adult rather than adult, if they were warm, or if they had been moving prior to an encounter. Weather conditions (air temperature, wind velocity and cloud cover) also influenced the snakes’ responses, as did season and time of day. The snakes’ response was relatively predictable from information on these factors, enabling us to suggest ways in which people can reduce the incidence of potentially fatal encounters with brownsnakes.

‘Snakes are first cowards, next bluffers, and last of all warriors’ (Pope 1958)