Reproduction

How does the Aldabra giant tortoise produce its young?

Breeding begins in February and ends in May. The eggs are carried by the female for ten weeks.

Males are highly territorial and fight one another to gain a territory and breeding rights with the females within.

During mating the male and female will make a deep grunting noise.

Nine to twenty-five eggs with a rubbery shell are deposited into a dry and shallow nest which the female will dig. These eggs are each around the size of a tennis ball.

On average about half of the eggs are fertile. Females in high density areas produce smaller clutches, less frequently. In low density areas they may produce several clutches each season.

It takes eight months of incubation before the eggs hatch. This means they will emerge from their eggs between October and December.

Maturity is not reached until somewhere between 20 and 30 years of age for this species.

Behavior

What does the Aldabra giant tortoise do with its day?

These animals vary between being solitary and roaming in herds.

Most of their activity occurs in the morning. This is when they go browsing for food aiming to avoid warm temperatures. During the day they may dig underground or rest in a puddle of water.

Much of their day is spent sleeping. This may take up 18 hours of their day.

Aldabra giant tortoises will wallow in mud. This provides protection to their skin against mosquitoes.

These animals will allow birds and lizards under their shell or in to skin folds where they remove parasites which may be attached to them.

Credit: Zoos Victoria

Predators and Threats

What is impacting the survival of the Aldabra giant tortoise?

Predators include dogs and goats who eat the tortoises along with their food. A species of giant crab living on the island feeds upon young tortoises.

Climate change is posing a large threat to this species. They were previously hunted to near extinction by sailors but have since been offered legal protection and this trade has now slowed.

Quick facts

Aldabra giant tortoises appear to have no fear of humans which is part of the reason settlers were able to hunt them so easily.

They were referred to as the ‘ninjas’ of the tortoise world by Mexican biologist Jose Antonio de Alzate y Rammirez. This is due to the perilous acrobatic acts they undertake to reach low hanging branches.

There used to be 18 tortoise species living in the Indian ocean with all but the Aldabra giant tortoise hunted to extinction by sailors along with the rats, cats and pigs that they brought to the islands.