Keepers have removed the eggs from the nest a normal process that allows staff to increase the chances of a successful hatching. The egg is replaced with an artificial one which the parents continu to care for.
Lots of dedication goes into caring for the egg including weighing it. One egg which was laid on February 13 weighed in at 249g (0.5 pounds) this week. This was a 14 percent decrease in weights from last week’s health check meaning fluid content in the egg is getting lower as the chick grows and develops at a healthy rate.
“All eggs lose weight as they develop,” explained Debbie Marlow, senior keeper at the San Diego Zoo Safari Park. “It seems counterintuitive because as the chick grows you would expect there to be a weight gain, but egg shells are porous and moisture is lost through the shell by evaporation during the incubation process.”
After weighing the eggs keepers also check on the air cell, where the embryo is positioned and how the blood vessels are developing. This is done holding up a warm light to the egg which means you can see inside.
55 days after the egg was laid it will begin to pip meaning it is ready to hatch. At this point they will replace the artificial egg with the fertile one. This means its parents are able to help the chick hatch and then they can raise it.
The San Diego Zoo Safari Park has experienced great success with their California Condor breeding program. During the 1980s they were on the brink of extinction with only 22 condors in the world. Now 400 condors can be found flying throughout California, Arizona and Mexico. 85 of these are animals released by the Safari Park. Over time the park has bred 185 condors.
Photo Credit: San Diego Zoo Safari Park/ Ken Bohn