February 27th is "International Polar Bear Day." This day was established to raise awareness among many people about the current situation of wild Polar Bear. Last year, we shared our efforts to artificially inseminate "Ikoro" (male) and "Dea" (female) on this day. Unfortunately, it did not result in pregnancy, but this time we will share our efforts since the artificial insemination.

Following artificial insemination in January of last year, we continued to monitor Dea's behavior and take blood samples.

Polar Bear in captivity often exhibit behavioral changes during pregnancy, although there are individual differences. These changes include changes in their food preferences and increased wariness towards males. Since Dea has never given birth, it is unknown what changes she would experience if she were pregnant.

Based on advice from several zoos and aquariums with breeding experience, we recorded the animal's daily feeding habits and behavioral changes, and from late September we suspended its exhibit and continued 24-hour video observation, but we could not confirm any particular changes. We also continued taking blood samples about once a week to check for changes in blood hormone levels associated with pregnancy, but the changes in those values also led us to conclude that the possibility of pregnancy was low.

We reopened the exhibit in late December and are currently making preparations for this season's breeding season.

*Dare herself seemed to enjoy life in the birthing room and remained calm throughout the period.

Unfortunately, last year did not result in pregnancy or childbirth, but we were able to observe Dea's behavior in the birthing room and any changes in her preferences over a long period of time.

This season, Dea has yet to show any signs of estrus. We will carefully observe the behavioral changes of both dogs, and also refer to changes in hormone levels from ongoing blood tests of Dea to determine the appropriate time for them to live together and for artificial insemination. After that, we will determine whether or not she is pregnant, based on a comparison with Dea's behavioral data from the previous season.

Last year, Polar Bear were born at several zoos and aquariums across Japan. We will put even more effort into Ueno Zoo 's first polar bear breeding program, aiming to increase opportunities for more people to see Polar Bear and to encourage interest in wild Polar Bear.

Dea extends her right front leg for blood collection.	Ikoro has also started training to draw blood.

[Ueno Zoo East Garden Animal Care and Exhibition Staff]

(February 27, 2025)