Written by: Chania Watts
It’s not often that you get to see crocodiles hatching and watch the whole process from start to finish. So we were very lucky at Selous Impala Camp when a large female crocodile decided that the bank right below the camp was the perfect nesting ground.
The nesting season for crocodiles falls between August and December, and the eggs are incubated for between two and three months so we eagerly awaited the young crocodiles’ arrival. During this time the nest is extremely vulnerable to predators such as monitor lizards, eagles, baboons, marabou storks, genets and hyenas, who will take any chance they can get to dig up the nest and eat the eggs. However, our mother crocodile was vigilant, very rarely leaving the bank – not even to eat.
She only left to cool down in the river for short periods but was never too far away. In fact we saw her on more than one occasion chasing off the marauding monitors, viciously protecting her precious eggs.
Now what’s interesting about crocodiles is that they have temperature-dependant sex determination, which means the sex of the hatchlings is not decided by genetics but by the temperature during their incubation period. If the temperature is between 31.7 and 34.5ºC the offspring will develop as males, if the temperature is above or below this range, the offspring will develop as females. Here in the Selous Game Reserve in Tanzania, the temperatures averaged between 31 and 40ºC during those months, so we can assume that there was a pretty even number of males and females produced.
After a long two and a half months the wait was finally over, and we woke one morning to the mother digging up her nest. The hatchlings make a high pitched chirping sound before they hatch. And upon hearing this, the mother will help to dig them out of the nest, as they are unable to get out themselves.
It was fascinating to watch her as she even helped to crack open some of the eggs, rolling them between her tongue and upper palate. She then began to ferry her young to the safety of the water where she had chosen a small pool covered by overhanging bushes to be their temporary nursery.
We watched her take the young into her mouth, sometimes tossing them into the air to readjust and hold them properly. Seeing her be so gentle and careful with them was amazing. We often associate crocodiles with being dangerous and vicious predators, so being able to witness firsthand this other side to their personalities was incredible.
She would carry between four and six each trip and made around 10 trips to and from the water, meaning she must have laid around 50 eggs!
There were a few tense moments when she left the exposed nest and a couple of fish eagles flew overhead, as we worried that they might take the chance of an easy meal and grab one of the remaining young. However, the mother crocodile was quick to rush back and ensure that her babies were safe.
Once they were all in the safety of the water, she remained close by, and she will keep protecting them for a few more months until they are big enough to look after themselves.