Within the same population, nesting green turtles (Chelonia mydas) might exploit different niches by exhibiting polymorphic foraging strategies and/or inhabiting geographically distinct foraging areas. This is crucial information for the conservation of this species. Here, we used stable carbon and nitrogen isotope ratios (δ¹³C and δ¹⁵N) to test for differences in a population of green turtles nesting on Príncipe Island (1°37′N; 7°24҆′E), Central Africa. A total of 60 nesting females were sampled on the two main nesting beaches of the island in December 2012. Minimum curved carapace length (CCL) was recorded, and δ¹³C and δ¹⁵N values were measured in the epidermis of each individual. Overall, CCL varied from 87.0 to 108.0 cm (mean ± SD =100.0 ± 5.1), δ¹³C values from −19.4 to −8.6‰ (−17.3 ± 1.8) and δ¹⁵N values from 7.9 to 17.3‰ (13.6 ± 1.5). Despite the large variation in both isotopic ratios, their distributions were unimodal, showing an absence of polymorphic foraging strategies and isotopically distinct foraging areas. However, smaller females (< median, 100.8 cm) occupied a much larger isotopic niche (i.e., four times greater) than larger females. These results suggest that nesting green turtles may forage opportunistically on the resources available in each of their foraging home ranges, with smaller females venturing to more isotopic‐diversified areas and/or exhibiting broader foraging strategies than larger females. In addition, and in accordance with other studies, findings suggest that the foraging grounds used by the Príncipe green turtle nesting females are distributed mainly throughout the Gulf of Guinea.

中文翻译：

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几内亚湾普林西比岛上筑巢的绿海龟（Chelonia mydas）的同位素生态位宽度（δ13C和δ15N）基于大小的差异

在同一种群内，筑巢的绿海龟（Chelonia mydas）可能会通过表现出多态的觅食策略和/或居住在地理上不同的觅食区来利用不同的生态位。这对于保护该物种至关重要。在这里，我们使用稳定碳和氮同位素比率（δ ¹³ C和δ ¹⁵ N），以测试在绿海龟筑巢普林西比岛的群体差异（1°37'N; 7°24҆'E），中非。总共60只嵌套雌性在2012年12月在岛上的两个主要嵌套海滩采样最小弯曲甲壳长度（CCL）被记录，和δ ¹³ C和δ ¹⁵在每个人的表皮中测量N值。总体而言，CCL从87.0变化到108.0厘米（平均值±  SD = 100.0±5.1），δ ^13个C值从-19.4至-8.6‰（-17.3±1.8）和δ ¹⁵N值从7.9到17.3‰（13.6±1.5）。尽管两种同位素比率都有很大差异，但它们的分布是单峰的，表明缺乏多态觅食策略和同位素上不同的觅食区。然而，较小的雌性（<中位数，100.8 cm）比较大雌性占据更大的同位素生态位（即，大四倍）。这些结果表明，筑巢的绿海龟可能会在它们的每个觅食地范围内利用可用的机会进行觅食，雌性较小的雌性会冒险进入同位素更多样化的区域，并且/或者比大雌性具有更广泛的觅食策略。此外，根据其他研究，研究结果表明，普林西比绿海龟筑巢雌性所使用的觅食地主要分布在几内亚湾。