Energetics and food requirements of the female snake Phillodryas chamissonis during the breeding season.

1.The energetic performance and food requirements of female Phillodryas chamissonis was determined during its breeding season at different ambient temperatures. 2. If the long tailed snake is active for 24 weeks, 25 to 32 30-g rodents are required for reproduction and maintenance. This is slightly more than one rodent per week. 3. The energy cost of reproduction (38 to 48% of total metabolism) is close to the values reported for fish (35% of metabolizable energy). 4. Due to their low metabolic rates, the theoretical predation pressure (on a prey biomass basis) exerted by the snakes should be 2 to 2.5% of that expected for endothermic predators of similar body size.