Detecting elusive aspects of wildlife ecology using drones: new insights on the mating dynamics and operational sex ratios of sea turtles

Offspring and breeding (operational) sex ratios (OSR) are a key component of demographic studies. While offspring sex ratios are often relatively easy to measure, measuring OSRs is often far more problematic. Yet highly skewed OSRs, and a lack of male-female encounters, may be an important extinction driver.
Using loggerhead sea turtles (Caretta caretta) as a case study, we showed the utility of drones, i.e. unmanned aerial vehicles (UAVs) to distinguish adult males and females in a marine breeding area, using a combination of morphological characteristics (tail length) and behavioural differences (active mating, courting and searching by males versus resting by females). Through repeated surveys, we documented seasonal changes in the OSR.
While the number, and ratio, of males and females on the breeding grounds changed massively, the ratio of receptive females (derived from the rate of influx of new individuals to the area) to breeding males remained close to 1:1 for much of the peri...

子代性别比与繁殖期（操作）性别比（OSR）是种群统计学研究的核心组成部分。尽管子代性别比通常相对容易测量，但OSR的测定往往困难得多。然而，高度偏离的OSR以及雌雄个体相遇匮乏，可能是重要的灭绝驱动因素。
以红海龟（Caretta caretta）为案例研究，我们展示了无人机（即无人驾驶飞行器，UAV）在海洋繁殖区域区分成年雌雄个体的实用价值——这一方法结合了形态特征（尾长）与行为差异（雄性的主动交配、求偶及搜寻行为 vs 雌性的休息行为）。通过重复调查，我们记录了OSR的季节性变化。
尽管繁殖地雌雄个体的数量及比例发生了巨大变化，但可受孕雌性（由该区域新个体流入率推导）与繁殖期雄性的比例在大部分peri...期间仍接近1:1。