Elephants are amazing creatures. Smart, peaceful (usually), and big. Really big. Which means they eat a lot.

So, when you have too many of them, it can become a bit of a problem.

That's the deal in South Africa right now. Nearly a century ago, it had just over 100 elephants. But through conservation, it now has more than 20,000.

Problem is, South Africa is running out of room on reserves, where many of the elephants are. And adult elephants eat about 100 to 300 kilograms of food a day. If the population grows too large, vegetation could be devastated.

So, what to do? Well, rather than a mass cull, South Africa is going with birth control. And no, we're not talking giant condoms or sponges or anything.

The plan is to inject female elephants with a vaccine, that enables the immune system to block male sperm. The vaccine is administered by a dart each year.

Ecologists say it's reversible, it's nearly 100 per cent effective, and it doesn't harm the elephants in any way.

The program has actually been in place on a small scale for 10 years. Now, officials want to expand it to give them time to develop more land for the elephants.

South Africa's neighbour Botswana has the same problem. It has at least 133,000 elephants (that's one elephant for every 14 people).

In fact, they've eaten so much that entire forests have been wiped out.

Oh, and just in case you run out of things to talk about at a party, here's some fun facts about elephants to get you through...

Elephants are the largest land-living mammal in the world

There are two types - the African elephant and the Asian elephant

Female elephants start to have babies at 12 years old and are pregnant for 22 months

An adult elephant needs to drink 210 litres of water a day

Elephants can swim and use their trunk like a snorkel to breathe in deep water

If by chance, your elephant conversation really takes off, there are more fun facts here.

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