Notes From The Zookeeper: The Pancake Predicament

One of the things I love about my job is the constant need to problem solve. It’s an unending puzzle.  How do I get a fat snake to breed? How do I help said fat snake reduce her girth so that she is healthier? How do I keep each animal’s brain and instincts engaged according to their needs? As a zookeeper, we have to think outside of the box all the time. But this week, a puzzle popped up that was totally INSIDE the box; the nesting box.

Pancake Tortoises (Malacochersus tornieri) are one of my favorite species. They are weird and funny, and they have unexpected super powers. I spray the tortoises daily to raise humidity, and this week after I sprayed them, I found this (please forgive the quality of photos, or lack thereof. I had to use the camera on my little phone):

how to breed pancake tortoise

Check it out! She is digging a nest for egg-laying! Note the dirt on her back. She kicks up quite a bit of it as she digs.

Tortoises are not domesticated animals. Although they have the ability to learn, they operate almost entirely on instinct. Pancake Tortoises, like most other tortoises, like to dig deep in order to lay their eggs. Like, really deep. When they nest, they dig, dig, dig with their hind feet, and if they hit a hard spot, say a rock or in this case, the bottom of their enclosure, they stop. Their tortoise instinct says that a shallow nesting spot is worst than NO nesting spot. They abandon the hole and move to higher ground. That’s what happened here. She dug, she dug, she quit.

Here’s the tough bit. I don’t know exactly what conditions she is looking for. Depth, of course, but she doesn’t know how deep the soil is until she starts digging. Other factors come into play. Some tortoises (and it can vary even within a species) will choose a warmer spot. Others will prefer a cooler one. Some want shelter, some want space. So what does she want? When I add soil to make it deeper, she might choose a shallow spot. When I add water so that it holds together, she choose a dry one.

This is where it gets fun. Remember that super power I mentioned? This species of tortoise can CLIMB! They live in kopjes, which are basically giant rock piles. To visit the neighbors or make a love connection, they may need to scale a few rocks. They especially like to climb…wait for it… when they are ready to nest. So if the soil is too deep, she can climb out of the house and go on walkabout. It’s for this reason that we keep a heavy cover on the enclosure.

My solution this time was to heap up a pile of wet soil that was wider than she is long so that she would have deep soil no matter which way she angled her body. She nested under the heat lamp last time, so that’s where I built Mount Pancake. Would it work? The next morning, here she was:

Look! She's basking! Reptiles are cold-blooded, so she may be warming up for the hard work ahead

Look! She’s basking! Reptiles are cold-blooded, so she may be warming up for the hard work ahead

A couple of hours later, I came back, and she was nowhere in sight. I found her under her hide box, but the mountain looked the same. Most tortoises and turtles cover their nests so completely that you would never know they had been there. Had she nested? I checked.

The egg was so fresh, it was still slimy. But it looks good! How do I know? The egg couldn’t have been more than 90 minutes old, and it had already started to band.

Banding is the first indicator of fertility. It’s a sign that the embryo and air pocket have begun to make their separation.

This egg was immediately popped in the chiller. Without cooling for a few weeks at 65 degrees, the egg embryo will never develop. Once placed in the incubator at 88 degrees, it will take about three months before it hatches.

Stay tuned next week when I share photos from my most recent hatching and maybe let you know if The Professor has made any inroads on wooing his lady.

She's on the left. The Professor is on the right. It sure looks like he's been friend-zoned.

She’s on the left. The Professor is on the right. It sure looks like he’s been friend-zoned.

Fun Friday: Hatching Season Begins

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.

The hatchling waits until most of its yolk is absorbed to begin emerging.

The hatchling waits until most of its yolk is absorbed to begin emerging. This egg was laid in October and hatched in January. Incubation lengths vary widely depending on methods used. Note the completely shredded appearance of the egg. The hatchling did all that with just its egg tooth.

Calcium aids in muscle contrations. After a long rest, they begin to eat the egg shell, possibly for a calcium boost.

Calcium aids in muscle contractions. After a long rest, they begin to eat the egg shell, possibly for a calcium boost.

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?

The Secret Keeper.

I know something you don’t know. I think. Maybe. Unless you’re my boss, and then you already know. But that only accounts for one of you. The rest of you are in the dark. I’ve got a secret. A cool one. And I can’t tell you. Maybe tomorrow, or next week. Soon. Very soon. It’s killing me. I want to blab. Since I can’t yet, I’ll share some pictures instead.

Many of our animals at the zoo are maintained in breeding colonies. Most of them produce eggs in their season. We have a big incubator to house all the eggs. There’s a reason, though, that we don’t count our tortoises before they hatch. Sometimes, for whatever reason, they don’t hatch at all. Sometimes embryos don’t ever complete their development, or they never actually develop at all. Sometimes they weren’t fertile to begin with. Things go wrong, and it’s just a part of the job.

And sometimes we get surprises. We were surprised this week. There was this egg, see. And candling… Remember candling?

Candling a snapping turtle egg. Note that it is vascularized. The shadow on the right is the developing embryo.

Candling a snapping turtle egg. Note that it is vascularized. The shadow on the right is the developing embryo.

When the light was shined through the egg, there was a lot of empty space. It appeared that the embryo just didn’t make it. There’s a reason we hang on to eggs for months beyond their expected hatching date. I took a quick peek in the incubator the other day and saw this:

See  the little nose peeping out?

See the little nose peeping out?

It’s a pancake tortoise (Malacochersus tornieri)! So cute and flat! The next morning, I checked his progress, and he was still hiding out in that egg, probably absorbing his yolk before he made his way into the world. Later in the afternoon, I noticed he was on his way out!

These images are best viewed as a slideshow. Click on the first one to enlarge, and then click the right arrow that appears to see them in order.

So you want to see something crazy? Of course you do!

And does he still look like a pillbug? You tell me:

Nope! All resemblance to pill bugs was your imagination!

Nope! All resemblance to pill bugs was your imagination!

 

In case you didn’t get to read all the captions, this is the first tortoise I have ever seen emerge from its egg entirely. I’ve caught dozens in various stages of hatching, but never like this. Amazing. I love my job!

It’s About Time!

I’ve officially been taking care of tortoises in the Herpetology department at my zoo for two years now. Over that time, I have to admit I’ve found some favorites.

Ploughshare tortoise. One of the rarest animals in the entire world. There are fewer than 400 left in the wild.

Ploughshare tortoise. One of the rarest animals in the entire world. There are fewer than 400 left in the wild. Their carapaces are etched to discourage theft. It does not hurt the tortoise.

 

 

Here's the fun. There are TWO of them in here! See them?

Bog turtles. This is one of my zoo’s special long-term projects. Actually, any tortoise breeding program is a long-term project, since it can take 10-25 years for them to get to breeding size.

 

The curve of the carapace (top shell) is incredible, but check out the wrinkles in the plastron (bottom shell)! I love how it has its little nose pulled in. Its face reminds me of Homer Simpson. And those bumpy things on either side are its legs.

Spiny Hill turtle hatchling. The hatchlings are always my favorites. I love how squished up it is. After hatching,  this turtle unfolded into its flatter and more proper proportions.

 

For 2 years, my favorite adult tortoises have been the pancake tortoises, Malacochersus tornieri.

Please excuse the weird green color. Without a flash, my camera likes to break down the light from the ultraviolet lamps into greens. Pretty, right

Please excuse the weird green color. Without a flash, my camera likes to break down the light from the ultraviolet lamps into greens. Pretty, right? Click to enlarge and really get a look at that face!

 

They are unbelievably cool. Instead of being rock-hard like other tortoise shells, the shell of the pancake tortoise is rather spongy.In the wilds of eastern Africa, they defend themselves by wedging tightly into narrow crevices in rock.  Their conservation status in the wild is listed as Vulnerable, which means that their numbers are okay at the moment, but sudden loss of habitat will leave them in serious jeopardy. Without the rocky terrain, they cannot survive.

For two years, I have been wishing and hoping for babies from our two pairs to no avail. The females haven’t been the most maternal and have scrambled the eggs before they could be retrieved. So frustrating! Until now.

Last week was the best week ever. Within 24 hours, I finished my novel, hit a major blog milestone, and got to meet someone new and precious. Ladies and gentlemen, I bring you Short Stack.

Hatching is serious business. And kind of messy. We have two pairs of adults - a pretty pair, and a less attractive pair. Can you guess the parents of this one by looking at the egg?

Hatching is serious business. And kind of messy. We have two pairs of adults – a pretty pair, and a less attractive pair. Can you guess the parents of this one by looking at the egg? Click to enlarge

 

This species is interesting when it comes to hatching, too. The incubation range is anywhere from 99 days to about 237 days. That’s a huge range. Other species tend to be a little more predictable. This guy (gal?) hatched at the lower end of the range, which is what caught me by surprise. Personally, I wasn’t expecting Short Stack to make an appearance until April. I do love surprises!

See that tiny crumb on the end of its nose? That's called an egg tooth, and it's what a baby reptile uses to shred the egg from the inside when it's time to hatch.

See that tiny white crumb on the end of its nose? That’s called an egg tooth, and it’s what a baby reptile uses to shred the egg from the inside when it’s time to hatch. Let me know if you don’t see it. I’ll show it to you in the next post.

 

Here’s some more exciting news. There’s another egg in the incubator, this one from the other pair. It has been candled and seems to be developing well.

 

So that’s my week. What exciting things are going on in your world?