Individuals and groups within the same population may differ in their use of resources. Also referred to as niche specialization, such differences can be documented through direct or indirect observation of resource or habitat use. Here, we examined selective habitat use in alliance-forming male Indo-Pacific bottlenose dolphins, Tursiops aduncus, in Shark Bay, Western Australia. Using 6 years of sighting data (2001–2006), we calculated the home ranges of 17 male alliances (comprising 3–14 individuals each). We defined five habitat types in the study area and measured the proportion of each habitat type in the home range of each alliance. Habitat selectivity was examined using selection ratios of used and available habitat within alliance home ranges. Since home range is also a form of habitat selection, we also examined selection ratios of alliances within defined subareas within the study area. Subareas were the combined home ranges of subsets of alliances that were linked by general location, distinctive habitat features and seasonal movement patterns. During each sighting, the predominant group behaviour was recorded. We analysed data from all sightings (which included all behavioural types: resting, travelling, socializing and foraging), as well as a restricted set of foraging groups only. For all sightings, alliances were selective of habitat within each of three subareas (northern, central, southern), and 14 alliances were selective of habitat within their home range. For foraging sightings, alliances within all three subareas were selective with respect to foraging habitat, and seven alliances showed significant selection of foraging habitat within their respective home ranges. Some alliances with broadly overlapping ranges foraged in different habitats. Alliance-specific habitat use may be influenced by ecological and social factors. Our results raise the possibility that the considerable variation in alliance size within this population may be influenced by the distribution of food as well as the distribution of females.

中文翻译：

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西澳大利亚鲨鱼湾雄性印度太平洋宽吻海豚的特定联盟栖息地选择

同一人口中的个人和群体在使用资源方面可能有所不同。也称为生态位专业化，可以通过对资源或栖息地使用的直接或间接观察来记录这种差异。在这里，我们研究了西澳大利亚鲨鱼湾形成联盟的雄性印度太平洋宽吻海豚 Tursiops aduncus 的选择性栖息地使用情况。使用 6 年的目击数据（2001-2006），我们计算了 17 个男性联盟（每个包含 3-14 个人）的家庭范围。我们在研究区域定义了五种栖息地类型，并测量了每个联盟的家园范围内每种栖息地类型的比例。使用联盟家庭范围内已用和可用栖息地的选择比率来检查栖息地选择性。由于家庭范围也是栖息地选择的一种形式，我们还检查了研究区域内定义的子区域内联盟的选择率。子区域是由一般位置、独特的栖息地特征和季节性运动模式连接起来的联盟子集的组合家庭范围。在每次目击期间，主要的群体行为都会被记录下来。我们分析了来自所有目击事件（包括所有行为类型：休息、旅行、社交和觅食）的数据，以及一组受限的觅食群体。对于所有目击事件，联盟在三个子区域（北部、中部、南部）中的每一个区域内都选择了栖息地，14 个联盟在其家乡范围内选择了栖息地。对于觅食目击，所有三个分区内的联盟都对觅食栖息地有选择性，和七个联盟在各自的家庭范围内展示了大量的觅食栖息地。一些具有广泛重叠范围的联盟在不同的栖息地觅食。联盟特定的栖息地使用可能会受到生态和社会因素的影响。我们的结果提出了这样一种可能性，即该人口中联盟规模的相当大的变化可能受到食物分布和女性分布的影响。