O'Connor, we often had to search for her by boat, pickup truck, remote station 

 at ANWR observation tower, or airplane. The other seven dolphins showed 

 more confined ranges, traveling within a usual radius of about 12 km from 

 Home Base (Fig. 6b-c). No differences were found in range size by age, sex, or 

 reproductive condition. A regression of range size on number of days tracked 

 showed a moderate linear correlation (P = 0.02, R^ = 0.53, n = 10), indicating 

 that range estimates for some individutds might have benefited from further 

 tracking. However, range sizes did not change appreciably for most dolphins 

 past the first week of data collection. In addition, from subsequent photo- 

 surveys we believe that the duration of the radio-tracking effort was sufficient 

 to describe the ranges of most of the radio-tagged dolphins. 



Dolphins moved between Matagorda and Espiritu Santo bays via the 

 three linking waterways: the ICW, Big Bayou, and Saluria Bayou (Hg. 1). 

 Telemetry indicates that dolphins used both the ICW and Steamboat Pass to 

 move between Espiritu Santo and San Antonio Bays. FB501 used Ayres 

 Dugout to move between San Antonio and Mesquite Bays (Fig. 6a). 



On only three occasions did we obtain evidence of radio-tagged dolphins 

 leaving the confines of the bay system to swim in the open Gulf of Mexico. 

 All three positions were v^ithin 1 km offshore of Pass Cavallo, based on signal 

 strength and bearing. FB518 (11-yr old male) was positioned offshore on 

 20 July 1992, and FB522 (8-yr old male) on 23 July and 29 July 1992. On 29 July, 

 FB522 may have been offshore for 6-7 hr, based on the inability to detect a 

 signal following his initial offshore positioning. Because of errors iriherent in 

 positioning dolphins by triangulation (as exemplified in Fig. 3) and the 

 changing influences of habitat structure and climate on signal strength (Mech 

 1983), movement offshore could in reality have occurred somewhat more or 

 less often. 



Males were found in the extremities of their ranges more often than 

 females (for horizontal and vertical coordinates P < O.CKK)!, n = 863 male 

 positions, n = 455 female positions, variance ratio F-test). FB501 was excluded 

 from this analysis because her "dual home range" movement pattern differed 

 from that of the other radio-tagged dolphins (see below). Similar results for 

 random equal subsamples of male and female positions indicate that the 

 higher male variance is not due simply to larger sample sizes. No differences 

 in geographic distribution were found for pregnancy, v^dth-calf, or age class, 

 perhaps due to small sample sizes. No differences in geographic distribution 

 were found for group size class, behavior, or time of day. That is, mother/ calf 

 pairs, or feeding dolphins, etc., were not found in particular areas of the study 

 site. 



13 



