At Ueno Zoo 's bison enclosure, a male American Bison named "Gunma" (born May 19, 1990) lives with three Collared Peccary: "Ai" (born September 29, 2002), "Mii" (born September 22, 2004), and "Mai" (born August 20, 2005). They have been living together since July 31, 2006, so it has been over seven years now.

Initially, the two species sometimes fought, but they have since maintained a reasonable distance from each other and lived together peacefully.

One day, a strange sight was witnessed in the bison enclosure. Mii, Collared Peccary, was diligently rubbing her rear end and back against the face of Gunma, American Bison. Gunma didn't seem to mind and allowed Mii to rub against him.

◎Video filmed by the author: Collared Peccary and American Bison (13 seconds)
　　Windows Media format　QuickTime format

This behavior had been observed before, but the reason was unknown. This time, too, we considered various reasons, such as whether Mii was in heat towards Gunma, or whether her bottom was itchy.

One possibility considered was communication among peers.

Collared Peccary naturally live in large groups of several dozen individuals. Within these groups, they are known to communicate by rubbing the scent glands on their backs against the backs and shoulders of other members, and this behavior of touching and rubbing against each other has been observed at Ueno Zoo.

Collared Peccary don't have very good eyesight or hearing, but they have an excellent sense of smell. They seem to maintain group cohesion by rubbing their scent on the places they move around and on other members of their group.

While interspecies rubbing behavior like this is rare, Mii may have wanted to leave her scent on Gunma as one of the animals living there.

However, they often get into skirmishes with each Collared Peccary over food, and sometimes they bother Gunma, who is a completely different size, and bite his legs. I still don't really know if they get along or not.

In any case, I am impressed every day by the generosity of the people of Gunma who patiently endure whatever Collared Peccary do to them and live peacefully.

Although scent marking behavior has rarely been observed since then, please pay attention to the relationship between the two species when you visit the bison enclosure.

◎ Tokyo Zoo Net BB video"Peccaries and Bison Living Together" (August 18, 2006)

Photo: "Mii" is in the foreground on the left.

[Yasumasa Inomata and Natsumi Uno, Animal Care and Exhibition Staff, Ueno Zoo, East Garden]

(Added March 1, 2024) Upon reviewing individual records such as the animal cards, we discovered an error in the ages of two of the animals, excluding the eldest daughter. We have corrected the article by swapping the text for these two animals. We apologize to all the fans who have been following the three animals since their arrival at the zoo for providing incorrect information for so long.

(September 6, 2013)
(March 1, 2024: Corrected the characteristics of the second and third daughters)