Starly is an avian Pokémon with primarily grayish-brown plumage. There is a white marking on its face, resembling a mask, and a white spot on its chest. The top portion of the mask marking is smaller on the female. The rest of its head and the lower half of its wings are black. Starly has a long, orange beak with a black tip and oval, black eyes with white pupils. A small tuft of feathers curls over the back and its head, and a small, pointed ruff surrounds its neck. It has two black tail feathers with a white feather between them. Its feet are orange with three toes in the front and one in the back. It preys on small Bug Pokémon. In the anime, it has also been seen consuming the acorn-like Berries grown on the bushes of Grotle.
Although capable of flapping its wings powerfully, Starly is weak and inconspicuous when alone. It forms large flocks to protect itself. However, individuals will begin to bicker if the group becomes too large. This Pokémon’s cry is harsh, and its singing can become annoying. Starly congregates in mountains and fields, where it hunts for bug Pokémon.
Multiple Starly appeared in the Hoopa's Surprise Ring Adventures short Flying in the Air. They were among the immense Flying-type Pokémon summoned by Hoopa to create wind for Ash and Pikachu, but their combined Gust was too much for them and sent them blasting off.
Multiple Starly appeared in Zoroark: Master of Illusions as some of the many local Pokémon living in Crown City. A flock of them worked together with the other Pokémon in surrounding Zorua in the park, intent on attacking him as retribution for what Zoroark did to the city. Before a fight broke out, the Starly, along with the other Pokémon, were calmed down by Celebi.
"A Starling Pokémon. It usually lives and travels in large flocks, so a single Starly will go unnoticed. To make up for this, its call is very noisy. It can often be found in places with heavy vegetation. Its small frame and cute appearance belie the incredible power with which it flaps its wings. When it levels up, it evolves into Staravia."
In Generation V games, Starly's Hidden Ability is the same as its first Ability, Keen Eye, unlike its evolutions, which have the Hidden Ability Reckless. A Starly which will evolve into a Staravia with Reckless can be bred to produce Starly that will evolve into a Staravia with Reckless. If a Starly that will evolve into a Staravia with Reckless is transferred to the Generation VI games, its Ability will become Reckless.
This means that in Generation V, Starly is the only unevolved Pokémon without a Hidden Ability that evolves into a Pokémon with a Hidden Ability.
Overworld sprites of Starly are shown in the intro of Pokémon Diamond, Pearl and Platinum and before the player and their Rival encounter them in battle. They are the only non-legendary Pokémon to get overworld sprites in the Pokémon Diamond, Pearl and Platinum series that are not allowed in Amity Square.