Evil Eagle

Background
Evil Eagle is what it's name suggests - an evil eagle. The villain who "pilots" this monstrosity is the mini-boss of the same dungeon, Grim Creeper. Up the ladder outside of the tower is the Grim Creeper and two of his "brothers" on top. Grim Creeper will say, "BAH! I'm not going to hold back!  I'm going to make you wish you were never born!!" Evil Eagle will come, the two "brothers" will fly away, and Grim Creeper will jump on the eagle as the boss music starts.

Strategy
Have your Mirror Shield out and that button pressed at all times. You can't be hurt very easily with your shield blocking all of his attacks. Evil Eagle will fly back and forth across the screen at varying altitudes until you hit him in the beak three times with any of the following weapons: the Hookshot, the Boomerang, the Bow, or the Magic Rod. Assuming you're using the Hookshot, Boomerang, or Bow, after three hits Evil Eagle will hover to the side of the tower and either blow wind at you and shooting little feathers (to combat this, keep your shield up and walk towards the wind - if you go past him, stop before you get to the edge), or he will dive at you (in which case, you can hit him with your weapon of choice). You'll know if he's diving after a few seconds, because you won't be moving backwards. If you manage to accidentally fall off the edge of the tower, you'll have to climb back up and start all over again (as Evil Eagle somehow regains all of his health if you fall off). Anyway, after blowing wind or diving, he'll start flying around again, randomly stopping to attack you. With the Hookshot and Boomerang, it'll take 8 hits to kill him. With the Bow, it takes 6.

Secret Strategy
The Magic Rod (which was mentioned earlier as a weapon of choice for this boss) is in Level 8: Turtle Rock. However, Level 7 is not yet finished. Even so, all that is needed is the Shield L-2 (Mirror Shield) and the Frog's Song of Soul (Song 3) to get into Turtle Rock. Once the Shield is retrieved from Level 7, Level 8 is reachable. The Magic Rod is used to defeat Hot Head and, simultaneously, Level 8 (and get the 8th instrument before the 7th - it doesn't really matter, though), or go back and beat Level 7 first. It doesn't matter which course you choose - you'll end up beating them both at some point anyway. Okay, back to Evil Eagle. With the Magic Rod, Evil Eagle simply flies around until you hit him three times. He will never directly attack if the Magic Rod is used.

Aftermath
Once you defeat Evil Eagle, Grim Creeper will say, "My energy...gone...I...lost! But you will be lost too, if the Wind Fish wakes!  Same as me...you...are...in...his...dream..." A Heart Container and the Organ of Evening Calm are retrieved as a reward.