At Ueno Zoo, once a year, a mass capture is conducted to verify the individual Black-tailed Prairie Dog, and at the same time, the soil in their enclosure is replaced for hygiene purposes.

In the early mornings of this season, most prairie dogs are sleeping in their burrows, so work is carried out at this time. On November 16, 2015, the staff gathered at 7 a.m., and the six of them formed pairs to attempt to capture the prairie dogs while they were asleep. Most of the dogs can be captured with this "sleeping raid operation," but any prairie dogs that are not caught are captured in parallel with the soil replacement work in the enclosure.


Black-tailed Prairie Dog sleeping in their burrows in the early morning.
Prairie dogs normally live in both burrows and enclosures, so unless they are injured or particularly ill, it's usually difficult to observe their individual conditions in detail. The annual mass capture also serves as a health check.

The captured prairie dogs are weighed, microchips are inserted for individual identification, their sex (for those born this year) is determined, and detailed checks are performed on their teeth, claws, and other features.


Scenes from the soil replacement work.
Replacing the soil in the enclosure also serves as a means of capturing any remaining individuals. When digging up the soil, we had to proceed carefully to avoid injuring any of the remaining animals. We started replacing the soil at 10 a.m. and finished capturing all the animals and replacing the soil at 4 p.m. All the staff Ueno Zoo pitched in to help with the work from 10 a.m. onwards, and we were able to complete it in a full day.

The soil that was previously used in the prairie dog enclosure has been piled up around Collared Peccary enclosure. Since there are beetle larvae and other insects in the piled-up soil, the peccaries, which have an excellent sense of smell, seem to be engrossed in searching for their treats in the soil.


Collared Peccary eating its food.
Come and see the prairie dogs busy digging tunnels in their new enclosure, and the peccaries busy searching through the piles of soil in their enclosure.

[Eri Yoshimura, Animal Care and Exhibition Staff, East Ueno Zoo East Garden]

(November 27, 2015)