Yes, pinwheels do help keep birds away, especially if you purchase metallic ones that really reflect the sun.

How do pinwheels repel birds?

Bird Deterrent - This visual reflective ornamental bird blinder pinwheel uses wind motion and light reflections to keep birds away coming from any angle.

Do birds like pinwheels?

Pinwheels

Those made of shiny materials like foil are intended to send the birds away. It's a combination of movement and blinding shimmer that will discourage the birds from paying you another unwanted visit. The good thing about pinwheels is that each piece is small and you can place it almost anywhere you want to.