Student smells a giant rat

Do you get rats bigger than the cats that hunt them?

Separating fact from urban myth is hard, but one researcher believes she has discovered our biggest urban rodent.

It is a brown rat 40cm long, from its nose to the tip of its tail, and it weighs 573g. Not as big as a cat but still scary.

For more than a year University of Pretoria postgraduate student Rolanda Julius has been travelling across Gauteng catching rats. Like the rest of us, she wants to know just how big they can get.

"All animals have size limits; what the limit is for rats in South Africa we don't know," said Julius.

It is because we know so little about the urban rat population that Julius is studying them.

The biggest rat she found was caught in Diepsloot, in Gauteng.

"I guess you could say it was the size of a small cat," said Julius.

Most of the rats Julius caught weighed in at about 300g and were about 25cm long. Informal settlements produced the biggest rats, she found.

South Africa has a reputation for big rats. The UK's Daily Mail ran a disputed story in 2011 about a metre-long rat in Soweto that attacked a baby.

South Africa's biggest rodent is the cane rat, which usually stays clear of urban areas but can grow to about two-thirds of a metre and about 8kg.

There are two main types of urban rat: the brown and the black, both invasive.

"The biggest rats I have seen were the size of puppies," said exterminator Abel Mahasha, who says the biggest rodents live in Alexandra, northern Joburg.

Exterminator Cobus Kellerman said: "They can be quite vicious and sometimes attack." Soweto was home to the biggest he has seen.

What Julius and the exterminators agree on is that the rat population is growing.

"In South Africa we have little information on their place in the ecology, and population sizes, but we hope to change that," she said.