Trumbeak is an avian Pokémon with black feathers. It has a long beak that tapers to a sharp point. The majority of its beak is orange, changing to light red and then black at the tip. The beak is flexible and can be bent to produce over one hundred different calls. It has round blue eyes and pale gray eyebrows. Pointed feathers extend from the back of its head and form a short crest. A white marking covers its face and extends down over its chest; the undersides of its wings are also white. Around its neck is a jagged, red band, and it has a long tail with three tail feathers. It has spindly blue legs with two toes facing forward and two facing backward.
Trumbeak feeds on Berries and stores the seeds in its beak so it can fire them off in a burst when encountering both enemies and prey. New plants grow from the seeds that Trumbeak scatters. The cries that it makes with its beak prove to be very noisy to its neighbors. Trumbeak lives in areas dense with trees.
Trumbeak appears to be based on a woodpecker, most likely a Pileated woodpecker or an Ivory-billed woodpecker. It also bears some resemblance to honeyguides or a toco toucan, especially one that has yet to fully mature. Its noisy calls could be inspired by various songbirds, which use a variety of sounds to attract mates and defend territory. Its ability to bend its beak may reference rhynchokinesis, the ability of some birds to flex their upper beak.
It also appears to be somehow related to various brass instruments: its names reference trumpets, its category is the "Bugle Beak Pokémon", and its ability to change its call by bending its beak is similar to that of a trombone, which works by altering the length of the slide.
Trumbeak may be a combination of trumpet and beak.
Kerarappa may be a combination of 啄木鳥 keratsutsuki (woodpecker) and 喇叭 rappa (trumpet).