It has an internal organ that senses the earth's rotation. Using this special organ, a Hoothoot begins hooting at precisely the same time everyday.
Biology
Physiology
(From Bulbapedia) Hoothoot is a round, owl-like bird with two stubby wings and a short, fan-shaped tail. It has large red eyes with beady pupils. Its feathers are mostly brown with a beige underbelly. Hoothoot has a large black, mask-like crest, which encircles both eyes and covers the face. The crest has two protrusions at the top resembling the hands of a clock. The parts of the crest below each eye have notches resembling the teeth of a clockwork gear. Hoothoot has a small, hooked beak and two feet with five digits. Although it will typically only stand on one foot at a time, it alternates between the two at speeds too difficult to track with the naked eye.
Inside Hoothoot's body lies a special organ that senses Earth's rotation, allowing it to keep track of time. Hoothoot is well known for its ability to keep rhythm by precisely tilting its head in time, much like a metronome. Every day at exactly the same time, a Hoothoot will begin hooting. Because of this skill, Hoothoot was considered a divine messenger of time and was raised to served as clocks a long time ago. Hoothoot is most commonly found nesting in trees and forests.
(From Bulbapedia) Hoothoot seems to be based on a combination of an owl—more specifically the Eagle Owl—and a clock, as its crest's prongs are shaped like the hands of a clock; in addition, it has the ability to keep track of time.
Name origin
(From Bulbapedia) Hoothoot is derived from hoot, an onomatopoeia for the sound an owl makes. It may also be a combination of hoot and cuckoo, as in a Cuckoo clock, referring to Hoothoot's keen ability to keep track of time.