In the wild, the age of young elephants (less than 15 years old) can be determined by the size of the footprint they leave behind in the dirt. The front-to-back length of the footprint (the print is shaped like a tear drop) is related to height, and both footprint length and height are related to age. It has been very useful to researchers to be able to determine age of calves in the wild in this way because it does not require any unnatural disturbance. Researchers can simply watch where a calf leaves a footprint, and when the animals have moved on, measure the print left behind in the dirt.
We wanted to compare the footprints of our calves with elephant footprints found in the wild, so we could see how growth in zoos compares with wild growth. All of our elephants are trained to walk onto a scale once a week and stand still while weights are recorded. We wet the scale before each calf entered and we then called them to walk across dry concrete with wet feet, leaving clear footprints behind after their weigh in. We were able to measure these after each calf was released back into the yard for afternoon play.
As it turns out, our calves are growing at the same rate as calves in the wild. For example, two-year-old calves in the wild have footprints that fall between 8.5 and 9.3 inches (21.8 and 23.7 centimeters). Our two-year-old calves, Impunga and Kamile, had footprints that were 9.4 and 9 inches (24 and 23 centimeters), thus falling within or close to the expected range. Both Musi and Khosi followed this same pattern. Our calves are growing very steadily; in November, Kamile weighed 1,030 pounds (467 kilograms), Punga 1,338 pounds (607 kilograms), Khosi 1,561 pounds (708 kilograms), and Musi a whopping 3,384 pounds (1535 kilograms)! Although our young males are getting bigger, they will remain with their family at the Wild Animal Park for the coming years. Because animals can’t be weighed in the wild, we will be comparing the growth in weight with the footprint size as they get older. However, so far it looks like our calves are growing bigger and heavier by the day!
The new elephant exhibit at the San Diego Zoo, Elephant Odyssey, is still on schedule to open in early summer of this year. None of the African elephants at the Wild Animal Park will be relocating, but the Park’s Asian elephants will find a new, large and comfortable home in Elephant Odyssey.