The defensive strike of the Eastern Brownsnake, Pseudonaja textilis (Elapidae)

Abstract

Abstract1. The Eastern Brownsnake, Pseudonaja textilis, is a large (to 2 m), slender‐bodied, highly venomous elapid that causes most snakebite human fatalities in Australia. The response of recently captured snakes to human harassment was quantified. Using high‐speed film, the type of neck display, time taken to strike, strike accuracy, strike speed and effectiveness of bite were recorded.2. The snakes were surprisingly tolerant of harassment, especially at body temperatures similar to those that they exhibit in the field during the activity season. Smaller snakes spent more time trying to escape than did larger snakes. Most snakes gave warning prior to the strike, 58% by full (high) display and 19% by partial (low) display. Some 25% of strikes were bluff.3. Body temperature (over the range 18–36 °C) had little effect on most of the variables measured, including: the frequency of display and bluff, the duration of the strike (mean 0·28 s), the strike distance (mean 0·34 m), the mean overall strike speed (1·1 m s−1, range 0·25–1·80), the mean fastest strike speed (during 1/25 s, = 1·7 m s−1, range 0·3–3·4), or the accuracy of the strike.4. Instead, the type of prestrike display was related to strike speed and accuracy: strikes preceded by a full neck display were slower but more accurate (and more likely to involve venom transfer) than those preceded by minimal display.5. Contrary to popular opinion, Eastern Brownsnakes are reluctant to deliver firm bites in response to human harassment even when continuously provoked. It is estimated that only 15% of the strikes recorded had the potential to cause significant envenomation.