Cubero-Pardo Priscilla
Fundación Promar. Apdo. 11709-1000, San José, Costa Rica.
Rev Biol Trop. 2007 Jun;55(2):549-57.
Habitat characteristics influencing behavior in animal species vary locally. The influence that a particular environmental characteristic can have on a species depends not only on other variables, but on morphological, physiological and social conditions of that species. In this study, developed from June 1996 to July 1997, I studied whether specific behaviors are related to particular distribution areas and environmental factors in the bottlenose (Tursiops truncatus) and the spotted dolphin (Stenella attenuata). The study area was covered along oblicuous linear transects, and the behavior of single groups was observed from 15 min to 5 h. Environmental factors such as depth, temperature, salinity and distance from shore, among others, were considered. For the bottlenose dolphin, foraging/feeding activities showed exclusive coincidence with river mouths, coral reef and mangrove areas, while social and milling activities where seen close to feeding areas. Traveling occurred along different points parallel to the coast, with a low percentage of cases across the gulf (16.56 %), suggesting that the bottlenose rarely crosses from one side to the other. In the spotted dolphin, several behaviors were observed simultaneously in the schools and it was not possible to associate areas with particular behaviors. The lack of significant relationships among activities and particular environmental variables (ANOVA tests) is attributed to three aspects: (a) transitions among activities generally occurred into a low variable area, (b) dolphins often traveled along large areas without changing activities and (c) environmental conditions in Golfo Dulce are homogeneous. In the two species the highest average in the number of individuals per group corresponded to the category of active socializing, followed by traveling, passive socializing and feeding. In the case of the bottlenose dolphin, the smallest group size was associated with feeding activities (ANOVA, F= 2.624, p=0.037, n=156, df=4), while in the spotted dolphin the smallest group size corresponded to milling activities (ANOVA, F=3.817, p=0.009, n=51, df=4).
影响动物物种行为的栖息地特征存在局部差异。特定环境特征对某一物种的影响不仅取决于其他变量，还取决于该物种的形态、生理和社会状况。在这项于1996年6月至1997年7月开展的研究中，我研究了宽吻海豚（瓶鼻海豚，Tursiops truncatus）和斑点海豚（Stenella attenuata）的特定行为是否与特定分布区域及环境因素相关。研究区域沿着倾斜的直线样带覆盖，对单个群体的行为进行了15分钟至5小时的观察。考虑了诸如深度、温度、盐度以及离岸距离等环境因素。对于宽吻海豚，觅食/进食活动与河口、珊瑚礁和红树林区域完全吻合，而社交和游动活动则出现在靠近觅食区域的地方。游动沿着与海岸平行的不同地点进行，穿越海湾的情况占比很低（16.56%），这表明宽吻海豚很少从一侧游到另一侧。在斑点海豚中，在鱼群中同时观察到了多种行为，无法将区域与特定行为联系起来。活动与特定环境变量之间缺乏显著关系（方差分析测试）可归因于三个方面：（a）活动之间的转变通常发生在低变量区域；（b）海豚经常在大片区域游动而不改变活动；（c）杜尔塞湾的环境条件较为均匀。在这两个物种中，每组个体数量的最高平均值对应活跃社交类别，其次是游动、被动社交和进食。就宽吻海豚而言，最小群体规模与进食活动相关（方差分析，F = 2.624，p = 0.037，n = 156，自由度 = 4），而在斑点海豚中，最小群体规模对应游动活动（方差分析，F = 3.817，p = 0.009，n = 51，自由度 = 4）。
