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Aerial surveys are often used to estimate wildlife abundance. The probability of detecting an animal during a survey involves two processes: (1) availability bias when animals present in the search area are not available for detection and (2) perception bias, when some animals potentially visible to observers are missed. Estimating these two sources of bias can lead to improved abundance estimates. To improve in-water marine turtle abundance estimates from aerial counts we estimated: (1) perception bias using independent tandem observers and mark recapture models, and (2) availability bias by quantifying the effect of turtle diving behaviour and environmental conditions on the
detection probability of turtles.

Fuentes, MMPB, Bell I., Hagihara R., Hamann M., Hazel J., Huth A., Seminoff J., Sobtzick S.,  Marsh H. (2015). Improving in-water estimates of marine turtle abundance by adjusting aerial survey counts for perception and availability biases. Journal of Experimental Marine Biology and Ecology, 471, 77-83.

This work was funded by the National Environmental Research Program, the Australian Marine Mammal Centre, and the Torres Strait Regional Authority.