It's bad news for grey squirrels in Aberdeen - officials will start to cull the critters to help protect their red relatives from Tuesday.
Traps have been set to catch them after experts decided they were threatening the reds by eating their food. They also carry diseases that can kill reds.
One animal group, Advocates for Animals, is calling for an end to the cull saying it's cruel and won't work.
The traps will be used until experts decide their numbers are under control.
Ten cage traps have been hidden on the ground and disguised with bracken. The animals will be caught alive and killed with blow to the head.
Any other creatures caught in the trap - including red squirrels - will be released back into the wild unharmed.
As well as carrying disease, grey squirrels are bigger and more aggressive than red ones and this means they starve the reds out by snatching the food first.
Greys came over from North America more than 100 years ago and have spread across England and some of Scotland. This has led to a huge drop in the number of red squirrels in the UK.