Weasel numbers decline

 Over the last 50 years the population of weasels has halved.

Another study shows that 70% of  small mammal populations has declined in the UK.

However there is good news to, bats and deer populations have increased.

At Sussex University, researchers have looked at 40 small mammal populations over the last 50 years.

They discovered that the weasels and harvest mice were worst affected.

Fiona Mathews from the University of  Sussex said "We need to act now to stop ecosystem collapse."