A NEW TRANSMITTER FOR SMALL ANIMALS AND ENHANCED METHODS OF HOME-RANGE ANALYSIS

The use of radiotelemetry in studies of very small animals is still limited by the size of the transmitters and methods used to analyze spatial patterns in behavior. I developed a new telemetry transmitter with a mass of 260 mg and a new method to improve the spatial resolution of home-range analysis. With the smallest batteries, the complete tag has a mass of 390 mg and runs for 5-6 days, allowing radiotracking of flying animals with a body mass of greater-than-or-equal-to 7 g. The transmitter has a pulse rate of 4-9 Hz that allows location within a few seconds. To record the use of food resources by tit species (Parus sp.) during the breeding season, I developed a technique to triangulate the birds' positions with high precision in spite of their frequent movements. To improve the spatial resolution of home-range analyses, a new kernel estimation method was developed and compared with the conventional methods of harmonic mean and bivariate normal kernel estimation, respectively. Taking bearings once a minute, I recorded 20-40 valid locations/hour. The standard deviation of bearing error was +/- 1.4-degrees. Compared with conventional methods, the modified kernel estimation greatly improved the spatial resolution of home-range analysis. It made possible the analysis of use of individual trees relative to food availability, and revealed fine details about the use of space and time by the birds. My small transmitter and new method to analyze location patterns with high spatial resolution should facilitate observation and data analysis in behavioral studies of small animals.