Not that it necessarily will help your specific map, but you can also do it without a trigger.
Go to Data.
Sound Tab.
Scroll down to sounds that say "Ambience" in their title. ("Ambience_[Tileset here]").
Find the ambient sound name that is tagged with the original tileset for your map. Eg, if your map was created on the Haven tileset, find Ambience_Haven.
In the box to the right, right click to add or remove sounds. Removing the ambience file in this named sound object will remove the annoying birds. Better yet, you can add an ambience which is more spooky, such as Shakuras, and even add intermittent thunder claps.
This can be done in melee maps, too, and is a great way to add another dimension of different feel to your maps.
Not that it necessarily will help your specific map, but you can also do it without a trigger.
Go to Data. Sound Tab. Scroll down to sounds that say "Ambience" in their title. ("Ambience_[Tileset here]"). Find the ambient sound name that is tagged with the original tileset for your map. Eg, if your map was created on the Haven tileset, find Ambience_Haven. In the box to the right, right click to add or remove sounds. Removing the ambience file in this named sound object will remove the annoying birds. Better yet, you can add an ambience which is more spooky, such as Shakuras, and even add intermittent thunder claps. This can be done in melee maps, too, and is a great way to add another dimension of different feel to your maps.