Diumality and week-by-week movement patterns were similar within 

 and among most dolphins throughout the study (Appendix 4 and 5). The 

 basic patterns were exemplified by FB518, an 11-yr old male tracked for 

 61 days. He ranged between the SW portion of Matagorda Bay, from Sand 

 Point to Pass Cavallo, and NE Espiritu Santo Bay (Fig. 6c). He was never 

 tracked beyond 13 km from Port O'Connor and ranged v^thin an area 

 approximately 10 km in diameter, centered at Port O'Connor. There was no 

 strong shift in movement pattern by time of day (Fig. 7), and he showed no 

 overall change in movement pattern throughout his 61 -day- tracking jjeriod 

 (Fig. 8). 



FB518 illustrates several general movement patterns seen in the radio- 

 tracked individuals. (1) Dolphins were capable of, and often did, traverse their 

 range in several hours. (2) A dolphin traveled widely on some days, perhaps 

 crossing its range, while on other days movement was very confined, within 

 1-2 km^. This did not appear to have a temporal or geographic pattern. 

 (3) Dolphins tended to spend about 1-4 days in a particular portion of their 

 range. (4) Movement tended to be more confined at night than during 

 daytime. (5) Dolphins tended to visit the extremes of their ranges orxly in the 

 daytime. The assertions of (4) and (5) may be biased as a result of less sampling 

 effort at rught (fewer triangulations and no visual sightings). 



The range of FB501 differed from the patterns illustrated by FB518 because 

 FB501 apparently had 2 main areas of habitat use (near Port O'Connor and 

 ANWR, respectively) and traveled through the intervening 30 or so km 

 rapidly. While within one particular area, her movement patterns were 

 sinular to those of the other radio-tagged dolphins. 



SURFACING PATTERNS 



A subsample of available radio-telemetered surfacing-interval data gives 

 an overall x = 33.3 sec mean-dive duration (SD = 5.79, n = 10 dolphins, 

 508 averaged 30-min samples), surface durations of J = 6.3 sec (SD = 2.16, 

 n = 10 dolphins, 425 samples), and dive rates of x = 2.0 dives/min (SD = 0.30, 

 n = 10 dolphins, 507 samples). See Table 3 for a detailed breakdov^m of interval 

 data. Dive durations did not appear normally distributed; modes and medians 

 were to the left of means (Fig. 9, P < 0.05, Kolmogorov-Smirnov test for 

 normality [Zar 1984:92]). Over 50% of dive durations were less than 30 sec, 

 with maximum dive times reaching over 3 min on rare occasions, and 

 almost exclusively at night. 



Dive durations differed between day and night (but not crepuscular 

 hours), and across individuals. Night dives, at I = 35.4 sec (SD = 8.43, 

 n = 9 dolphins, 153 averaged 30-min samples), were significantly longer than 



14 



