Guay
Guays are small, crow-like creatures that appear in several games.
A Link to the Past
Their first appearance. They are often seen perched in trees, and attack when someone approaches.
Ocarina of Time
In Ocarina of Time, Guays are encountered mainly in large areas with lots of space, namely, Lon Lon Ranch (as a Child), Lake Hylia (as an Adult), and the Desert Colossus. They attack Link on sight by by dive-bombing him. They are one of three enemies in the game that have a huge version that comes after killing many small ones, along with Stalchilds and Leevers. This only happens in Lon Lon Ranch.
Majora's Mask
Guays are the same in Majora's Mask, excluding the enlarged variant and rarity. They are less common in Majora's Mask, appearing only in Ikana Canyon. Aside from that, one lone Guay can always be seen flying around the exterior of Clock Town. It seems to ignore Link, however.
The Minish Cap
Guays in The Minish Cap behave in much the same way as in A Link to the Past, but play a more prominent role. When Link visits Damp'e the Gravedigger, he recieved the gate key needed to open the door to the graveyard. When he exited the house, a Guay swooped down, steals the key, and retreated to its nest. Link traveled to the nest and was able to destroy it and steal the key back.
Twilight Princess
Guays in Twilight Princess are larger, slow-moving, and encountered in large groups. These groups are often found in trees, and fly out of the tree as Link approaches. Killing a group of Guays will often cause a small pile of rupees to fall from the sky.