Sorry to be a wet blanket, but in the US your proposal would likely result in charges for violating one of several "bird laws" such as the Bald and Golden Eagle Protection Act or Migratory Bird Treaty Act. Defending your property isn't sufficient justification for causing harm without the appropriate permits. Farmers for example are brought up on charges when they harm a bird of prey attacking their livestock, or when migratory birds are poisoned due to improper pesticide use.