There has been so much talk recently about the birthing season of the new impala lambs. You would have recently read Patrick’s blog about this exciting time with lambing season. I have always said that the turn of summer is my favourite time in the bush, and even more so with all the births of new animals.
One striking contrast I often speak about during this time is the gestation periods of predators and prey. Take, for example, a lion versus an impala. A lion weighs about five times that of an impala, stands much taller, has a robust build and can easily hunt down an impala. When looking at the two animals side-by-side, there is no comparison as to which looks more developed and powerful.
That being said, it’s surprising to find out that the gestation period for a lion is 3.5 months while that of an impala is 6.5 months – almost two times more than a lion! What’s the reason for this? Well, knowing nature and how everything happens for reason out here, there is a proper justification for how this works.
We’ll start with the animal on top of the food chain – the lion. Arguably the biggest and most dominant predator in Africa. With its powerful strength and large size, it comes as a bit of a shock that it only takes 3.5 months (around 110-120 days) for a lion to develop in its mother’s womb.
The gestation period is very quick since lionesses need to hunt to survive and provide for their pride. They would be severely disadvantaged if they were weighed down by heavy pregnant bellies for extended periods. As a result, the cubs are underdeveloped at birth – they are blind, weak and helpless. The term we use for this is altricial.
Plus the added risk of taking the hoof of a zebra to the abdomen during a hunt could prove to be fatal to both mother and unborn cubs.
Cubs can follow their mothers at about three months of age and are weaned by six or seven months. They begin participating in kills by 11 months but cannot properly survive on their own until they are two years old. This is the converse to their prey.
As impala are herbivores and only need to eat vegetation to avoid starvation, a pregnant belly does not impede their ability to get nutrients and there is no need for them to hunt. The extra time in the womb allows the lambs to be born with well-developed muscles, so they can move and see immediately once they drop. The term used for this is precocial. The reason the lambs need to be born so well-developed is that they immediately must be able to run and escape from predators.
The mothers keep feeding and communicating with the lambs by grunting. The youngsters drink only the milk their mothers produce for the first three weeks. This milk is filled with colostrum which helps build up the immune system. After these three weeks, they supplement that milk by eating leaves and grass. Between four to seven months the impala is completely weaned, and within two years the females are mature enough to have their own offspring.
There is a reason for everything in nature
One of the best things out here is knowing that each animal species has evolved and changed to fit the habitat and increase its chances of best survival. We often look at the physicalities of animals – a giraffe’s long neck; an elephant’s dexterous trunk; a kudu’s massive ears – but there is so much happening internally that we do not see. These internal phenomena, such as gestation periods that best suit each animal species perfectly, are the reason why species do as well as they do. In other words, there is a reason everything happens the way it does in nature.