was at least 50 km from an altitude of 800-1500 m. Details of tracking from 

 stationary and mobile antenna arrays can be found in Mech (1983). 



Data Collection 



Directional bearings were taken on each dolphin every 4-6 hr for the life 

 of the transmitter. Bearing entries included notes on signal quality (strength 

 and signal to background noise), estimated distance and location (based on 

 operator experience), environmental conditions, and a 30-min sample of 

 surfacing intervals when signal quality allowed for reliable data. Bearings 

 were often taken simultaneously from more than one location, allowing for 

 triangulated positions. During daylight hours, one of the vessels often 

 approached tagged animals by homing onto the signal. At such times 

 behavioral observations, photographs, and HI8 video recordings were made; 

 and exact positions, useful for comparisons to estimated and triangulated 

 positions, were obtained. These sightings also allowed radio operators at 

 remote locations to calibrate their distance and location estimates. Surfacing 

 intervals were obtained by noting the time, to the second, when the radio 

 signal was first heard as the dolphin surfaced. Also noted was the number of 

 pulses (beeps) received while the dolphin and transmitter were at the surface. 

 Previous and present experience indicate that almost all surfadngs 

 lasting < 2.5 sec are accompanied by a single breath. Longer surface times 

 indicate dolphins resting at the surface, or traveling or feeding in extremely 

 shallow (< 0.5-m depth) water. 



Data Analysis 



Radio-track analysis consisted of plotting telemetered locations onto a 

 map, and visually inspecting for movement patterns, distances traveled, and 

 geographical ranges (the area over which an individual moved in the course 

 of the study). Ranges (Fig. 6) were plotted with Canvas 3.5 for Macintosh 

 (Deneba 1992) by drawing a continuous area covering all telemetered and 

 visually sighted positions. Range sizes were calculated using Canvas' 

 "Calculate Area" command (Deneba 1992) and compared between males and 

 females, pregnant and non-pregnant females, females with calf and those 

 without, and age class (Mann-Whitney U). A simple linear regression was 

 performed to investigate potential dependence of range size on number of 

 days tracked for each of the dolphir\s. 



To investigate differences in range use between males and females, we 

 compared variance about the mean position. The mean horizontal and 

 vertical x-y coordinate was determined for each radio-tagged dolphin. 

 Horizontal and vertical deviations from the mean were calculated for each 



