SGER: The Use of Double Body Temperature Logging for Remote Sensing in Extreme Environments

Fordham University, Bronx NY

Investigators

Abstract

`SGER: The use of double body temperature logging for remote sensing in extreme environments Craig L. Frank Fordham University Ground squirrels are herbivorous rodents that fatten during the summer, and hibernate below ground from late fall through the following spring. The hibernation period of high elevation populations can be as much as 8 months. Previous studies have demonstrated that the diets of free-ranging ground squirrels vary greatly in polyunsaturated fatty acid (PUFA) content during summer fattening, and this appears to be related to both their torpor patterns and over-winter survival. The goal of this study is to detail the effects of natural variations in diet PUFA content on the torpor patterns and survival of high altitude populations of golden-mantled ground squirrels (Spermophilus lateralis), using a new technique for remote sensing called Double Body Temperature Logging (DBTL). This study will be conducted at the Barcroft facility (elevation = 12,470 ft.) of the White Mountain Research Station maintained by the University of California. The DBTL technique is comprised of two stages. One stage consists of placing temperature sensitive radio collars around the necks of S. lateralis collected during the fall, releasing them, and following the radio signals throughout the entire 7-8 month hibernation period using an automated radio receiver housed in the field station. These transmitters each emit a signal on a unique radio frequency. The pulse rates of the signals depend on skin temperature. The radio signals from the squirrels will be recorded at 4 h intervals using a Data Collection Computer (DCC) produced by Advanced Telemetry Systems (Isanti, MN). A DCC is a radio receiver that has an internal computer, and can be programmed to scan for a particular set of radio frequencies at preset time intervals. When a radio signal is found, it records the frequency, date, time, and pulse rate on an internal hard drive. These data can then later be downloaded to a regular computer for subsequent analysis. In the second stage of DBTL, body temperatures will also be measured at 4 h intervals throughout the study by an " I-button" logger implanted into the abdomen of each squirrel. An I-Button logger (Dallas Semiconductor, Inc., TX) is a self-contained disc that weighs only 3.1 g, and is just 17 mm in diameter. It records temperature/time/date readings on an internal computer chip that can later be downloaded to a regular computer for analysis. Using the DCC/radio telemetry and loggers simultaneously will thus provide a greater number of complete body temperature records for the entire hibernation season than using either of these methods alone. The I-Button logger type proposed by the PI is new and considerably smaller that the logger types previously using to measure animal Tb. There are no previously published studies using this logger type to measure animal body temperate (Tb). The proposed study is both novel and high risk because it will be the first to use radio telemetry in conjunction with implanted loggers to: a) provide Tb data on some of the animals that could not be retrieved, and, b) assist with the location and collection of animals with implanted loggers. This proposed study thus represents 3 important leaps forward in the use of implanted loggers to remotely measure the body temperatures of free-ranging animals: a) the ability to use them in animals of only 1/3 the size of those in previous logger studies, b) improved logger/data retrieval rates, and, c) the first to attempt to measure the Tb of free-ranging animals throughout the moment of death from natural causes. This SGER proposal will provide a research opportunity for one undergraduate student.