A great egret looks for breakfast at Calamvale Creek

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Scientific stuff

Broad-shelled turtle
Also called
broad-shelled river turtle,
side-necked turtle,
broad-shelled snake-necked turtle

Species:
Chelodina expansa
(more recently, Macrochelodina expansa)
Family: Chelidae
Suborder: Pleurodira
Order: Testudines
Class: Sauropsida

Identification:
Large, long-necked freshwater turtle with very flattened pointy head and long, thick neck. Head, neck and limbs are grey.

Carapace (shell) is oval, wide, and flattened — broader at the tail end — and its colour may vary from grey to blackish brown. The plastron (the underneath part of the turtle's shell) is cream, and is narrower than the carapace.

Broad-shelled turtles are most often found in medium to large rivers, lakes and ponds, but also inhabit the larger parts of swamps, creeks, dams, and inland drainage systems.

They prefer cloudy water with considerable sediment, and like seclusion — lying concealed at the bottom of the water in sediment or debris. They are rarely seen except in autumn when females come out on land to nest, where they excavate a hole and lay between 5 and 30 eggs.

If you come across one on land laying eggs, stay well away, because if it is scared off it may not lay again for some time.

Size:
Adult carapace may grow to 50 centimetres (20 inches), and its head and neck are about 80 per cent as long as the carapace, making total length with neck extended up to about 80 centimetres (32 inches).

Personality:
Secretive, likes to be left alone. Doesn't like noise, excitement, or being disturbed. Definitely not a party animal.

Using our photos

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Photos of the eggs

Our photographer was excited when he found that Betsy the broad-shelled turtle's eggs had hatched at Calamvale Creek.

He said:

“It was a thrill to finally see that the little turtles had hatched.

“I was disappointed that I wasn't able to get photos of the hatchlings, but it's more important that they hatched and got down to the creek to continue the population of the creek's broad-shelled turtles.

“Turtles are wonderful creatures, and the whole process of egg-laying and hatching is a marvellously intricate miracle of coordination.

“I was careful when digging out the nest to try to keep things intact.

“But of course the clay and mud was friable and so the best I could do was to get the eggshells out in as good a condition as I could.

“I then put them back on the dirt to photograph them.

“As the sex of turtles depends a lot on temperature (males hatch after cooler weather or a long time incubating, while females hatch in warmer temperatures or shorter incubation times), I think our turtles were probably all baby boys.”

Critters of Calamvale Creek

Broad-shelled turtle eggs hatch

Also called:
broad-shelled river turtle, side-necked turtle, broad-shelled snake-neck turtle

Chelodina expansa (more recently, Macrochelodina expansa)

The turtle eggs hatch

Hole from which the baby broad-shelled river turtle hatchlings emerged

For several months I had been watching the area where 38 weeks ago I had seen Betsy the snake-necked river turtle lay her eggs.

Eggs of these broad-shelled river turtles (Macrochelodina expansa) can take between 192 and 360 days to hatch (roughly 18 weeks up to a year). So I had no idea when the hatchlings would decide it was time to come out and get down to Calamvale Creek, where their mother had come from.

But I did expect they would hatch after heavy rain. That was the time their mother had laid her eggs, and I realized rain would be needed to soften the clay so the little guys could dig their way out.

Every time there had been rain over the past few months I checked on the turtle nest.

Turtles hatch!

Then on a very rainy February 12 — 270 days after Betsy had carefully laid her eggs in the nest — I found there was a small hole, about 5 centimetres (2 inches) wide, right above the nest (see photo above).

A closer examination showed it was a tunnel leading up from the eggs. The babies had hatched!

Seven turtle eggs

I left the area undisturbed for many days, then finally decided to dig very carefully around the nest to see how many eggs were there. I came into the centre of the nest slowly in case there were any unhatched eggs still inside.

I found seven chalky white, slightly marbled, egg shells, but one of the hatchlings had not survived. The shells were full of mud, no doubt because of all the rain since the hatchlings had emerged.

chelodina_expansa_turtle_eggs_2 (54K)

The big surprise for me was that the shells were soft and pliable, not at all like hard birds' eggs. They felt more like damp fine-quality paper.

macrochelodina_expansa_turtle_eggs_3 (50K)

One of the eggs was intact on one side, so I cleaned it and put it on the dirt to photograph it (below). This belonged to the turtle that hadn't survived.

broad-shelled_turtle_egg_4 (35K)

It was broken on the side you can't see, and looked like it could have been broken since the time Betsy laid it. After all, she had to dig backwards without seeing what she was doing, so it's possible a rock fell back into the nest or Betsy had accidentally put her foot on it while laying.

Eggshells open like ribbon

The eggshells were very different in the way they had opened. Some had the small caps at the end separated; some had variously shaped holes in them, and others were just lots of small pieces.

chelodina_expansa_turtle_eggs_5 (42K)

One that especially interested me was the one below, which had unwound in a strip like a perfectedly formed ribbon.

broad-shelled_turtle_eggs_6 (63K)

How big are turtle eggs?

To give you a comparison of the size of the broad-shelled turtle's egg, I have placed one next to a small crested pigeon's egg and a large chicken egg (see below).

The crested pigeon's egg on the left is 30 millimetres long, the turtle's egg is 42 mm, and the large brown chicken's egg on the right is 57 mm.

eggs (40K)

Turtle hatchlings don't have a great survival rate. Kookaburras, butcherbirds, snakes and other predators abound. But because the day was so overcast and rainy, I suspect the six of these little broad-shelled turtle hatchlings at least made it down to the water.

— Robert Doolan

PS. See our photos of baby loggerhead turtle hatchlings. We photographed them on Mon Repos beach only a month after our creek turtles hatched. Boy, they're cute!