Tama Zoo would like to inform you that "Gopon," Greater One-horned Rhinoceros conducted with Yokohama Municipal Kanazawa Zoo, may be pregnant, and that her estimated due date is approaching.

A possible pregnant Greater One-horned Rhinoceros
name Gopon
sex female
age 24 years old
date of birth Born December 22, 1999 at the San Diego Zoo.
(Moved to Kanazawa Zoo on March 19, 2003)
Date of visit December 9, 2020
Past births (all births took place at Kanazawa Zoo)
February 1, 2007 Mes Asuka
August 15, 2009 Os Bunta
January 31, 2014 Os Champ


Greater One-horned Rhinoceros "Gopon" (Photo taken: June 12, 2024)

Progress so far
On May 9, 2023, mating with the male "Vikram" was confirmed. Since then, we have been observing Gopon's behavior and condition, and measuring sex hormone metabolites in his feces as part of a joint research project with Gifu University and others (*1).

As a result, based on three points—① the cessation of periodic behavioral signs of estrus, ② abdominal distension and swelling of the nipples, and ③ the continued high levels of progesterone metabolites in the feces, which are indicators of pregnancy—we determined that there is a high probability that the dog is pregnant and that pregnancy is continuing.

We have attempted to confirm pregnancy using ultrasound (echography) multiple times, but have not been able to confirm the fetus, and therefore have not been able to confirm the pregnancy.

*1 A joint research project by four organizations: Tama Zoo, Kanazawa Zoo, Tokyo Zoological Park Society Wildlife Conservatio Center, and the Animal Reproduction Laboratory, Faculty of Applied Biological Sciences, Gifu University.

Estimated date of birth
Assuming that the date of mating confirmation (May 9, 2023) is considered day 0 of pregnancy, the birth is estimated to be around August 2024.
*Regarding breeding
Female Greater One-horned Rhinoceros rhinoceroses reach sexual maturity at approximately 3 to 6 years of age. Their estrous cycle is reported to be 36 to 60 days, and their gestation period 460 to 496 days. They typically give birth to one calf at a time, with newborns weighing between 44 and 90 kg.

others
　We will be carrying out renovations to the enclosure in preparation for future births. Animal exhibits may be temporarily closed during the renovation work. We will inform you of further details once they are finalized.

(Added July 29, 2024) Starting August 1st, we will be closing the indoor exhibit of Greater One-horned Rhinoceros enclosure to prepare the indoor environment for the birth and to maintain a calm environment.

Please note that Gopon will be allowed to move freely between the outdoors and indoors, so he may not always be visible. Thank you for your understanding.

Past birthing records at Tama Zoo
On December 20, 1973, Saitaro (male) was born to Rani (female) and Tamao (male).

Current status of animal care at our zoo (as of June 26, 2024)
2 animals (1 male, 1 female)

Domestic breeding situation (as of December 31, 2023)
4 zoos, 7 animals (4 males, 3 females)
Source: 2023 Greater One-horned Rhinoceros National Pedigree Registry [Japanese Association of Zoos and Aquariums]

(June 26, 2024)
(July 29, 2024: Added information regarding the suspension of indoor exhibits at Greater One-horned Rhinoceros enclosure)