Cardinal Alert is a decorative adhesive strip, 6 inches wide, that is placed at the bottom of a window which is being 'attacked' by Cardinals or Bluebirds.  These birds, especially males, see their reflection in your window and repeatedly attack the reflection, thinking they are driving off a competitor.

The Cardinal Alert strip blocks the reflecting surface along the windowsill, stopping the reflection and the attacks.

Each strip is four feet long and can be cut to fit.  Multiple strips may be needed for multiple windows.