DETERMINING MOOSE ACTIVITY BUDGETS USING LEG-MOUNTED TIP-SWITCH TRANSMITTERS AND A COMPUTERIZED DATA ACQUISITION SYSTEM

Abstract

Leg-mounted mercury tip-switch radio transmitters and a computerized data acquisition system (Telonics Inc., Mesa, AZ) were tested for the detection of 3 activities in moose (Alces alces): lying, standing and walking. Transmitters were mounted on the lower front legs of 9 study animals with nylon harnesses. Mercury switches were positioned such that signal pulse interval was long during standing, short during lying and variable during movement. The data acquisition system was programmed with frequencies to be sampled, sample period length, number of samples per sample period and time between samples.

Signal patterns predicted active and resting bouts correctly 99.2% and 89.4% of the time, respectively. Errors resulted when transmitter switches failed to trip when animals laid down, or when animals held their legs at an angle while feeding. Error was reduced by using a sampling design which optimized the detection of movement during active periods (3-minute sample periods) and allowed comparisons of consecutive samples such that samples containing ambiguous data could be re-evaluated (15-minute intervals). The number of steps taken within 808 15-second periods was predicted with 1 step, 95% of the time. Lengths of individual walking bouts lasting over 5 seconds were predicted with a high degree of accuracy.

The system was further tested during a study in which 189, 24-hour activity budgets were obtained. The accuracy of estimating time spent walking, time spent active, and length of individual active and resting bouts are reported.