dugongs in palau - C3

crash of the airplane on a commercial flight during the course of the study. In this section, the data from
all five surveys are analyzed jointly in order to determine general patterns in distribution and habitat
utilization by the Palauan dugong population, and to provide relative information on adult and calf
numbers between surveys.
2003 Aerial Survey
The survey team consisted of a commercial pilot with previous dugong survey experience, a front-right
survey leader, two mid-seat observers and two rear-seat observers. The survey leader 3 and one observer 4
had previous experience of dugong aerial surveys. All team members occupied the same seats during each
flights, although their positions varied on consecutive survey days. On sighting a dugong, or group of
dugongs, an observer called out to the survey leader, who would instruct the pilot to circle the location so
that the sighting could be confirmed and number of individuals verified. Attempts were made to minimize
the effects of glare by ensuring that all observers wore grey polarized sunglasses.
The survey took place on three consecutive days between 8 th and 10 th March 2003 5 . A Britten-Norman
Islander high wing aircraft was used, flying at 185-204 km/hr (100-110 knots) at an altitude of 198 m
(650 ft). The four flight routes (Figure 3) covered in previous surveys were completed, with an average
survey time of 133 minutes (2 hours 14 minutes) per route. The total survey time was 535 minutes (8
hours 55 minutes). 6
3 Had participated in quantitative dugong aerial surveys on the Great Barrier Reef (Australia) in the 1980s, and led
the 1998 Palau dugong aerial survey.
4 Had participated in the 1998 Palau dugong aerial survey as an observer.
5 In the following results and analysis, the term “survey day” is used for each separate flight sector/route. However,
in 2003, due to very good survey conditions, two sectors/routes were flown on the last day (March 10, 2003). For
the sake of consistency with previous survey analyses, each of the two sectors/routes on that day are considered
separate “survey days” for analysis purposes.
6 Observers were asked to also individually record turtle sightings (i.e. sightings were not called out to the survey
leader for recording) in order to keep observers alert. However, this data was not recorded consistently by all
observers, and so cannot provide any usable information
5