Online ISSN : 1880-2117
Print ISSN : 0912-4047
ISSN-L : 0912-4047
35 巻, 2 号
  • 伴 和幸, 江﨑 美貴子, 川瀬 啓祐, 冨澤 奏子, 杉山 尚子, 椎原 春一
    原稿種別: 原著
    2019 年 35 巻 2 号 p. 73-79
    発行日: 2019年
    公開日: 2020/02/14
    ジャーナル フリー

    Blood analysis is an important tool for health management. Our zoo succeeded in being the first in the world to train our mandrills (Mandrillus sphinx), to allow venipuncture using only behavioral restraint. Two mandrills at Omuta City Zoo participated in this project, one male (A) and one female (B). We used PVC pipe to create a sleeve that could be attached to the enclosure and set a bar inside of it so that the mandrill would grip it underhanded, thus presenting the inner side of the arm. By partially blocking the top half of the inside of the sleeve, the mandrills were guided to use an underhand grip. This simplified the training, with less stress for both animals and keepers. The needle insertion was done into the cephalic vein. We used sweet potato as the unlearned reinforcer and a dog whistle as the learned reinforcer. The process was as follows: 1) excitatory conditioning, 2) gripping, 3) gripping underhanded, 4) avascularization, 5) epilation, 6) needle insertion. Training was held once a day for an average of 6-11 minutes. Number of sessions and cumulative time were 34 sessions/365 minutes for the A and 65 sessions/392 minutes for the B. The training has retained a high success rate (85% for the A, 79% for the B), allowing for regular blood sampling.

  • 豊田 有, 石垣 竜, 嶌村 泰人, 河合 よーたり, 長屋 良典, 丸橋 珠樹, MALAIVIJITNOND Suchinda
    原稿種別: 短報
    2019 年 35 巻 2 号 p. 81-85
    発行日: 2019年
    公開日: 2020/02/14
    ジャーナル フリー

    The stump-tailed macaque, Macaca arctoides, is the most distinctive in its genus with respect to reproductive anatomy and sexual behavior. Male-male mounting behaviors have been mentioned in many reports; however, ejaculation has not yet been recorded.
    Herein, we report a very rare case of ejaculation in the context of male-male mounting in wild stump-tailed macaques in Khao Krapuk Khao Taomor Non-hunting Area, Thailand. The behavior was observed during documentary filming of the animals. Daily observations were conducted for 28 days from July 4th to 31st, 2018, from 8 am to 6 pm. This rare behavior was documented on July 12th, while following and filming the Wngklm group. A young male of this group, WKM-M33, and a young male of another group (Fourth group), FTH-M33, started mounting. Initially, this mounting seemed to be social interaction in the context of a group encounter. However, after a thrust of a few seconds, the mounter, WKM-M33, exhibited ejaculated-like behavior. The mountee, FTH-M33, exhibited teeth-chattering behavior and touched the mounter's genital area. After completion of the mounting, whitish semen dropped to the ground and was eaten by WKM-M33. Then, WKM-M33 squeezed out sperm from the erect penis and ate it. We were therefore convinced that the mounter, WKM-M33, had ejaculated at the time of mounting.
    Although it is dificult to draw a definitive conclusion because it is a single case report, we propose two possible interpretations: 1) accidental case owing to extreme tension from group encounters during social interaction or 2) homosexual behavior between males with little access to females.

  • YOSHIKAWA Midori, OGAWA Hideshi
    原稿種別: 短報
    2019 年 35 巻 2 号 p. 87-92
    発行日: 2019年
    公開日: 2020/02/14
    ジャーナル フリー

    タンザニアの乾燥疎開林地帯であるウガラ地域で1995年から2012年にチンパンジー(Pan troglodytes)の直接観察を行った。ウガラはチンパンジー分布の東端にあたり,最も乾燥して開けたチンパンジー生息地の1つである。チンパンジーは単位集団が離合集散してパーティーと呼ばれるサブグループ(以下,単に集団と呼ぶ)を形成するが,発見した52集団のうち59.6%は樹上,32.7%は地上にいた。また,59.6%は川辺林,38.5%は疎開林にいて,草地にはいなかった。彼らはアカンボウを除き平均3.1頭(最大10頭)という小さな集団を形成していた。集団の大きさの平均は乾季には3.6頭,雨季には2.0頭であり,ウガラのチンパンジーは,果実の少ない雨季には小さな食物パッチでの採食競合を避けるために小さな集団を作る一方で,樹木が落葉し樹冠が開いて疎開林がより危険になる乾季には比較的大きな集団を作っていた。オスが1頭のみでいる事は8回あったが,メスがそうしている事は1回しかなかった。複数のオスとメスからなる混合集団にはオスは1.4頭,メスは1.9頭含まれていた。育児中のメスが母子のみでいる集団も3回記録されたが,育児中のメスは肉食獣等に捕食される危険を減らすためにオスよりも多く混合集団に加わっていたと示唆された。発情メスを含む混合集団の大きさは5.7頭だったが,発情メスを含まない混合集団の大きさは4.0頭だった。また,オス1頭とメス1頭からなるコンソート集団は4回記録されたが,複数のオスだけからなる集団は記録されなかった。広大な行動域に非常に低い密度で暮らすため,縄張りをパトロールする必要が低い半面,発情メスとはぐれないようにする必要があるためかもしれない。ウガラのチンパンジーは採食,捕食回避,繁殖戦略に応じて集団の大きさと構成を変えて乾燥疎開林地帯に適応していたと考えられた。