Tomato thief

Mum and dad have a load of tomato plants in pots out the back. They are bountiful and their fruit is delicious. However, mum has to make sure she picks them before they turn too red because there is a tomato thief outside which gets in first.

There has been some discussion around the identity of the tomato thief. Birds, cats, aliens have all been mentioned but mum is convinced it's this little chap. I'm not convinced.