Calf Sightings 



A maximum of 3 calves per county was sighted on any survey. Total percentage 

 of calves sighted ranged from 0.9% to 4.9% in different months, which is low compared 

 to surveys by other investigators. Calves made up 5.2% of the animals sighted by Odell 

 (1979) in Collier and Monroe Counties in 1973 through 1976, but during a 1976 winter 

 survey of the same area, 10.4% of the manatees sighted were calves (Irvine and Campbell 

 1978). Leatherwood (1979) counted 9.9% calves in the Indian and Banana Rivers in eastern 

 Florida, and Irvine and Campbell (1978) reported overall calf percentages of 9.6% in 

 winter and 13.4% in summer from surveys of the entire State. Odell (1979) suggested that 

 the tendency of calves to stay close to their mothers might result in fewer calf sightings 

 in turbid waters, but his hypothesis has not been verified. Too few calves were sighted in 

 our study to indicate seasonal reproductive trends. 



BOTTLENOSE DOLPHINS 



Abundance and Distribution 



Four hundred and thirty-one herds totaling 1,383 bottlenose dolphins were 

 observed. The total number of dolphins sighted increased from July to November, but 

 fluctuated in most counties with no obvious trends (Table 1). Sightings were most 

 common off the beaches, but were also frequent in interior bays and rivers in ENP and 

 well into Tampa Bay. In the Charlotte-Lee Counties area, dolphins were common in the 

 Gulf of Mexico, around Pine Island, and occasionally in the lower Caloosahatchee River. 

 Most coastal sightings were within 0.5 km of the beach. 



The dolphin sightings are of particular interest due to the paucity of information 

 on Tursiops truncatus in nearshore areas of western peninsular Florida. The sightings 

 were not analyzed for abundance and density estimates (see discussion by Leatherwood et 

 al. 1978), because flight routes were designed to optimize manatee sightings and were not 

 flown as straight lines. Our observations can, however, provide information on dolphin 

 herd size and habitat use. 



Herd Size 



Dolphin herd sizes were not sighted with equal frequency (Figure 3), and most 

 sightings (56%) consisted of 2 or more animals (P < 0.005; chi-square). Mean herd size for 

 the pooled sample of all sightings was 3.2 dolphins per herd (SE ±0.26). Effects of county 

 and month on average herd size in counties with sightings in each month (Table 2) were 

 analyzed as a two-way ANOVA. The county by month interaction was significant 

 (P < 0.0005), indicating that monthly variations in dolphin herd sizes were not comparable 

 among counties. A separate one-way ANOVA for each county indicated that monthly 

 variaton in herd size was significant (P < 0.05) only in Lee County, due to a high 

 December mean. Pooled sightings from all counties indicated that herd-size frequency 

 distributions varied significantly between months (P < 0.001; chi-square), with relatively 

 fewer single dolphins and more large groups ( >4) sighted in July and December. 



Average herd size was considerably smaller than herd sizes reported from other 

 aerial surveys in nearshore areas. In coastal waters of Alabama, Mississippi, and 



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