Great shot of Ranchipur (the 12,000 pound bull) and ChaCha (the "little" 5,300 pound cow). The other girls are larger, in the 7 to 8,000 pound range. I've overheard some visitors misidentify ChaCha as a baby because of her small size, even though she is about 40 years old.
I imagine it is just genetic, but it could be ChaCha's eating habits that have kept her small. I was there when keepers were hand feeding the two of them a variety of veggies. Ranchipur ate quickly and eagerly, even full heads of romaine or several celery stalks at a time. In contrast, ChaCha was taking a long time with smaller pieces, eating quarter or half-apple size pieces of yams and one lettuce leaf at a time. She was still eating well after Ranchipur was done. Finally her keeper dumped the rest of the bucket of food on the ground for her to finish on her own. Ranchipur looked interested, but made no moves to try to edge ChaCha away from her food as she slowly finished. Instead, he gave her space, moving over to pull some hay from one of the utilitrees.
the 30-35 rule is really only applied to females who haven't yet had a calf, which in this case all the females ( par a stillbirth think it was Mary?) haven't gievn birth before. Females in the wild may have calves until they are 50 or so.
All of the females at the San Diego Zoo are too old to breed. They range in age from 40-56. A keeper told me that Cha-Cha eats more than Ranchipur but she has a very high metabolism.
