Apparent twin pups of the weddell seal near Mawson, Antarctica

Phocid seals give birth annually, generally to a single pup. Twins have been reported occasionally, either from observations made in utero or from observations of live pups in the field. Examples of the former are reports of two embryos in a Weddell seal, Leptonychotes weddellii and of twin foetuses of a southern elephant seal, Mirounga leonina. Observations of two pups suckling one adult female have been reported for weddell seals. For southern elephant seals, an adult female that expelled two placentae and gave birth to a pup while another newborn pup was nuzzling the female, has also been reported. Here we use the expression 'apparent twins' to refer to reports of twin weddell seal pups that are based solely on field observations of two pups with the same adult female on several occasions.The data arising from this study has been recorded in the form of 3 observations. These observations can be found in the referenced paper. A copy of this paper is available for download as a pdf document from the provided URL.

海豹科（Phocid seals）海豹每年均可产仔，通常仅产下1头幼崽。偶有双胞胎产仔的报道，此类报道要么基于子宫内的观测结果，要么基于野外活体幼崽的观测记录。前者的典型案例包括：1头威德尔海豹（Weddell seal，*Leptonychotes weddellii*）体内发现两枚胚胎，以及1头南方象海豹（southern elephant seal，*Mirounga leonina*）的双胎胎儿报道。另有观测记录显示，威德尔海豹曾出现2头幼崽同时哺乳1头成年雌性个体的情况。就南方象海豹而言，也曾有报道称，1头成年雌性个体排出两枚胎盘并产下1头幼崽的同时，另有1头新生幼崽正依偎蹭抚该雌性个体。本研究中，我们采用"疑似双胞胎"这一表述，指代那些仅基于野外多次观测到同一成年雌性个体伴随2头幼崽的威德尔海豹幼崽双胞胎相关报道。本研究产生的数据以3项观测记录的形式留存，所有观测记录均可在引用的论文中查阅。该论文的PDF版本可通过给定的URL下载获取。