Eastern brownsnakes (Pseudonaja textilis) from south-eastern Australia are alert, well camouflaged, secretive, fast moving, and dangerously venomous, and they spend much of the time hidden in burrows. Thus, direct observation of this species is difficult. However, distinctive patterns in environmental thermal heterogeneity, coupled with knowledge of the thermal preferenda of the snakes, enabled us to infer their location and activity based on remotely monitored body temperatures (obtained from surgically implanted radio transmitters). We used data on 40 radio-tracked snakes to evaluate patterns of thermoregulation, activity, and habitat use.
Captive snakes actively selected body temperatures around 31 C, and free-ranging snakes displayed similar body temperature levels while active. From data on temperatures of the soil, operative models, and shaded air, we could identify activity schedules of the snakes (especially, times of emergence from and retreat into burrows). Snake activity was bimodal over the year, with the highest incidence of above-ground activity in late spring and late summer. Thermal profiles suggest that inactive snakes in burrows spent most of their time at approximately 20 cm depth, bur they moved to shallower depths at some times (e.g., during summer, when they sometimes spent entire nights above ground) and deeper at other times (e.g., ≥40 cm in winter). Reproductive females remained with their eggs after oviposition in mid-summer, about 30 cm under the soil surface. Burrow temperatures were frequently high, so that the snakes did not need to emerge in order to elevate body temperature. Overall, the telemetered snakes spent an average of 56% of active-season days, 64% of all days, and 93% of all hours below ground. Hence, this species largely depends on in-ground temperature for thermal energy exchange.
|Number of pages||17|
|Publication status||Published - Dec 2002|
- Activity schedules
- Microhabitat selection
- Thermal preferenda