If the VEMapOptions.EnableBirdseye property is set to false, then:

• The Birdseye map style button normally found in the map control dashboard will be absent.
  
  
• Keyboard shortcuts used to show the Birdseye map style in 2D and 3D will not function.
  
  
• The VEMap.SetMapStyle Method will not change the map style if VEMapStyle.Birdseye or VEMapStyle.BirdseyeHybrid are passed as values.
  
  
• The VEMap.SetBirdseyeOrientation Method, the VEMap.SetBirdseyeScene Method, and the >VEMap.Show3DBirdseye Method will do nothing.
  
  
• The VEMap.IsBirdseyeAvailable Method will return false at all zoom levels.
  
  

Reference