The Mosquitos/Killer Birds are some of the semi-common enemies in Beyond Dark Castle, they appear the Helicopter Pack levels, and show up in Beyond Dark Castle and Return to Dark Castle.
If you get touched by this enemy, you die.
The Killer Birds make the same sounds as the vultures when they appear on screen. The Mosquitos make a "Beep" noise.
The Killer Birds Appear in the Black Forest, and the Mosquitos appear in the Swamp
The Mosquitos/Killer Birds can only fly in one direction, and cannot stop, slow down, do any kind of attack. They can be killed by Rocks, or Fireballs.
For killing a Mosquito/Killer Bird you get 30 Points.
The Mosquitos/Killer Birds have stayed looking the same since Beyond Dark Castle, with the only real changes being color, in Return to Dark Castle.