METHODS 



Surveys were conducted during five periods: 24 through 29 July, 6 through 11 and 

 the 17th of September, 2 through 8 October, 2 through 8 November, and 3 through 9 

 December 1979. Weather permitting, surveys were conducted on consecutive days in a 

 chartered Cessna 172 aircraft at an air speed of approximately 160 km/h and an altitude 

 of approximately 150 m. The final day of the September survey was postponed until 17 

 September because of adverse weather caused by Hurricane Frederic. The flight on 6 

 December was shortened and flights scheduled for 7 and 8 December were cancelled due 

 to inclement weather. The cancellation of those flights prevented December coverage of 

 Charlotte Harbor and associated rivers, all of the Caloosahatchee and Orange Rivers, and 

 the area from Estero Bay (Lee County) south to the Broad River (Monroe County) in 

 ENP. The Whitewater Bay area of ENP was surveyed on 9 December 1979. After the 

 July surveys, an extra survey day was added to the schedule, and daily coverage was 

 redistributed to shorten flights in south Florida. Daily surveys lasted from 2 h 25 min to 

 6 h 21 min (x = 3 h 52 min). 



Flights usually began between 0730 and 0800 hours. The right door of the aircraft 

 was removed to increase visibility on the 7 September flight and on all flights in 

 subsequent months. One observer was seated in the right front and another in the left 

 rear. Sighting locations of all manatees, dolphins, sea turtles, sea turtle tracks, and 

 crocodiles were noted on charts of each area by the forward observer. Comments were 

 dictated into a cassette tape recorder, or noted directly on the chart. Calves were 

 defined as small manatees or dolphins closely associating with larger animals of 

 approximately twice their size (after Irvine and Campbell 1978). Dolphins or manatees 

 within an arbitrary distance of approximately 100 m of conspecifics were counted as 

 being in the same "herd" or group. Use of the term "herd" to describe social aggregations 

 of dolphins is well established in the literature (see review by Norris and Dohl 1980), but 

 "herds" of manatees are not known to occur (Hartman 1979, Reynolds In press). 



Flight routes were marked on maps of the entire western Florida study area to 

 facilitate consistent coverage on successive surveys. The routes were selected to cover 

 probable manatee habitat (Hartman 1974, Irvine and Campbell 1978). Survey routes 

 generally followed the 2 m bottom contour. The deep water shipping channel was also 

 surveyed in Tampa Bay. Pilots used the route maps to navigate, leaving the observers 

 free to scan for animals. The plane deviated from the route only to investigate sightings 

 and to count or photograph animals. 



•\reas surveyed included: (1) bays and estuaries; (2) the Caloosahatchee River to 

 the Ortona Lock in July, and to Moore Haven on other surveys; (3) canals, bayous, rivers, 

 and creeks ( > 1 m deep) up to 25 km inland; (4) the Intracoastal Waterway; (5) coastal 



