The evolution of marmot sociality: II. Costs and benefits of joint hibernation
- Arnold Walter
- Behavioral Ecology and Sociobiology
A polarimetric procedure is described for determining exponential mean temperatures (θe) from the rate of inversion of sucrose solutions buffered at pH values between 1 and 3. An equation is given for calculating the pH values appropriate for various temperature ranges and time scales. The procedure used for monitoring air and soil temperatures over a 5 year period at a network of sites in Aberdeenshire was to expose 5 ml volumes of sucrose solution at pH 2.06 in sealed polythene tubes. Each month the changes in optical rotation were measured with a sensitive automatic polarimeter and fresh tubes exposed. The values of θe were 2°C higher than arithmetic means obtained from standard thermometric devices. Observations at elevations between 275 and 686 m a.s.l. demonstrate the lapse of temperature with altitude and illustrate the usefulness of θe measurements.