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An Experimental Evaluation of Dugong and Sea Turtle Aerial Survey Techniques

机译：儒艮海龟航测技术的实验评估

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Some factors which affect the aerial counts of dugongs and sea turtles were examined experimentally. There was no significant difference in the observed density of dugongs when survey height was doubled from 137 m to 274 m with an accompanying doubling of transect width on either side of the aircraft from 200 m to 400 m. In contrast, a significantly higher density of turtles was observed at the lower heightharrower transect width. The higher level of glare on the exposed side of the aircraft, the time of day and the time from high tide made no significant difference to the observed densities of dugongs or turtles. The survey crew included a tandem team of two observers on each side of the aircraft, who reported their uncolluded observations into separate tracks of a two-track tape recording system. This allowed the reports of tandem observers to be compared in order to assess observer reliability. Overall, observers missed over 40% of dugong groups and over 80% of turtles visible within the transect including groups of more than 10 dugongs. The chance of observers missing a group of dugongs was independent of group size. There was little disagreement between tandem observers about the identification of animals, or the position of animals in the water column. However, observers differed markedly in their categorisation of dugong behaviour and in their counts of animals (particularly dugong calves) in larger groups.
机译：实验研究了一些影响儒艮和海龟飞行计数的因素。当测量高度从137 m翻倍至274 m时，所观察到的儒艮密度没有显着差异，同时飞机两侧的横断面宽度从200 m翻倍至400 m。相反，在较低的较窄的横断面宽度处观察到明显更高的海龟密度。飞机裸露的一侧较高的眩光程度，一天中的时间以及从涨潮开始的时间与所观察到的儒艮或海龟的密度没有显着差异。调查人员在飞机的每一侧都包括一个由两名观察员组成的串联团队，他们将他们未经证实的观察结果报告给两轨录音系统的单独轨道。这样可以比较串联观察者的报告，以评估观察者的可靠性。总体而言，观察员错过了40％的儒艮群，以及超过80％的海龟在样带中可见，包括10多个儒艮群。观察者错过一群儒艮的机会与团体人数无关。串联观察者之间关于动物的识别或动物在水柱中的位置几乎没有分歧。但是，观察者对儒艮行为的分类以及较大群体中动物（特别是儒艮小牛）的数量差异很大。

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    《Wildlife Research》 |1989年第6期|p.639-650|共12页
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