Any ideas on how to give crows the hint to stay away?
We have many repellent and control options when it comes to crows. You can see them all on our NUISANCE BIRD REPELLER page. The real key when it comes to crows is to first identify where it is you want to repel them from. Once you know the area you should be able to match up one of the options we have included on our product page. As you'll learn, there is a wide range of repellents that can be employed including mechanism's that work by smell, sight, sound and contact.
Here is a direct link to the page mentioned above: