Pedrazzi Giulia, Giacomini Giancarlo, Pace Daniela Silvia
Department of Environmental Biology, Sapienza University of Rome, 00185 Rome, Italy.
Biology (Basel). 2022 Feb 21;11(2):337. doi: 10.3390/biology11020337.
Epimeletic behavior toward dead calves has been frequently reported in cetaceans, mostly with females (presumed mothers) showing supportive behaviors such as carrying, lifting, or sinking, often assisted by "escort" individuals. However, information on acoustic production in such contexts is scarce. This report describes two observations of epimeletic behavior toward dead newborns in bottlenose dolphins and associated acoustic production. Data were collected at the Tiber River estuary (Rome, Mediterranean Sea, Italy) with one hydrophone for passive acoustic monitoring and two digital cameras. In both cases, an individual (presumed mother) acting as the main supporter and directly interacting with the carcass by lifting it (case 1) or sinking it (case 2) was observed. Another adult individual (escort) was present in both encounters showing standing-by and excitement behaviors (case 1) and supportive behavior (case 2). In both encounters, whistles, pulsed sounds, and bray-call elements were recorded. The consistent vocal activity observed likely conveyed context-specific information. A signature whistle in the first encounter was also recorded, likely emitted by the putative mother as a distress call. This report confirms the occurrence of epimeletic behavior in bottlenose dolphins and reports a preliminary description of the acoustic production when a dead calf is involved, providing additional information on this largely unknown topic.
在鲸类动物中，对死去幼崽的护理行为屡有报道，大多是雌性（推测为母亲）表现出诸如托举、抬起或下沉等支持行为，通常还有“护送者”个体协助。然而，关于此类情境下发声情况的信息却很匮乏。本报告描述了对宽吻海豚中针对死去新生幼崽的护理行为及相关发声情况的两次观察。数据是在台伯河河口（意大利罗马，地中海）收集的，使用了一个水听器进行被动声学监测以及两台数码相机。在这两个案例中，均观察到有一个个体（推测为母亲）作为主要支持者，通过抬起（案例1）或下沉（案例2）幼崽尸体与尸体直接互动。在这两次接触中均有另一只成年个体（护送者）出现，在案例1中表现出待命和兴奋行为，在案例2中表现出支持行为。在这两次接触中，均记录到了哨声、脉冲声和叫声元素。观察到的持续发声活动可能传达了特定情境的信息。在第一次接触中还记录到了一个特征性哨声，可能是推测的母亲发出的求救信号。本报告证实了宽吻海豚中护理行为的发生，并报告了涉及死去幼崽时发声情况的初步描述，为这个在很大程度上尚不为人知的主题提供了更多信息。
