In my job, each season brings its own mystery and magic. In the winter, many species lie dormant waiting for the warmth of spring. In summer, they are at their peak of activity, breeding and otherwise. In fall, they begin the mysterious process of shutting down for the winter to come. And spring itself? That’s the time of renewal. It’s at this time of year that when we check the incubator, we often see eyes staring back at us.
This year, hatching season got off to an early start. Our adult Pancake Tortoises (Malacochersus tornieri), a species native to countries in southern Africa, such as Tanzania and Mozambique, begin laying their eggs in the fall. This species is unusual, both in their day-to-day behavior and in their breeding. These tortoises can climb. And I don’t mean a little bit. They live in rocky kopjes, and they are gifted with the ability to scale rocks.They are also squishy. Their carapace has numerous fontanels that never close up, which allows the tortoise to squeeze into tight spaces between rocks to escape predators.
The females tend to seek higher ground when laying their eggs. They usually lay one egg at a time, and may lay 4-5 eggs over the course of a 4 month laying period. The eggs are huge at about 42mm (1.7 inches), impressive when you consider that the female is only around 6 inches long.
Here’s where things get weird. If a keeper were to place the egg into the incubator at 88 degrees, nothing would happen. Like, ever. This species experiences a diapause at the beginning of its development, which means it is laid in a state of suspended animation. Nothing happens unless conditions are right. Guess what the right captive conditions are? A wine chiller. The eggs are placed into a chiller at 65 degrees. Though other zoos do it differently, we’ve learned that a week or two at these cooler temps is all they need to get them going. After chilling, the warmer temperature of the incubator breaks the diapause and development begins. Diapause presents differently in many species, and one day I’ll do a post just on that. It’s weird and wonderful, setting up the juveniles to hatch at times when conditions in the wild are ideal for their survival.
So now pictures! Click any image to enlarge.
Happy Friday! I have more pictures and species to share soon. So far this year, we’ve hatched 10 individuals representing 3 threatened or endangered species.
What’s the good news from your week?