Tweeter

A Tweeter is a masked bird that appears in Super Mario Bros. 2.

Appearance
Tweeters are similar in stature and appearance to a Shy Guy, with their masks having a beak rather than a mouth hole. Despite the presence of wings, they rapidly hop rather than fly around in their debut appearance, reminiscent of a green Koopa Paratroopa. In their original artwork, they have red bodies, white masks and blue wings; in sprites and Super Mario Advance artwork, they have white bodies and red masks and wings. The Super Mario Bros. Super Show! uses a design similar to the original artwork, with tiny blue wings replaced with larger red wings.

Super Mario Bros. 2
Tweeters made their first appearance in Super Mario Bros. 2 as common enemies. Rather than walk normally, their movement consists of three short hops followed by a fourth hop its height, traveling straight ahead until hitting a wall. Like several other standard enemies, Tweeters can be simply picked up and thrown. In the NES version, they have only one sprite of animation, while in SNES version and other subsequent remakes, they have two sprites.

The Super Mario Bros. Super Show!
Tweeters made several appearances in The Super Mario Bros. Super Show!, where they were usually portrayed as allies of King Koopa. The first appearance of a Tweeter was in the episode "Butch Mario & the Luigi Kid." In this episode, a Tweeter bounty hunter, dressed as a cowboy, acted as an informant of Sheriff Mouser, telling him and his minions the location of Mario, Luigi and Toad, in exchange for Gold Coins. A horror-themed type of Tweeter called the Tweeter Bat exclusively appeared in the episode "Count Koopula". In "The Unzappables", one Tweeter represents a literal Stool Pigeon that rats out Al Koopone's plans.

Super Mario Bros. & Friends: When I Grow Up
A Tweeter makes a small cameo in the coloring book game Super Mario Bros. & Friends: When I Grow Up, under the Veterinarian page.

Super Mario-Kun
A Tweeter appears in volume 8 of Super Mario-Kun. Here, it attempts to puncture Mario's Cap, only to have Mario transform into Dr. Mario.

Nintendo Adventure Books
When Mario first arrives in the Mushroom Kingdom in Double Trouble, he spots some orange Tweeter birds (presumably sand clones created by GLOM) fighting for space on a brick ledge; later, it is mentioned that unfriendly Tweeters trying to land on his head are among one of the constant annoyances in the otherwise beautiful kingdom.

If Mario and Luigi follow Princess Toadstool to the Koopahari Desert in Pipe Down!, they will be attacked by a flock of Tweeters, which will also appear to attack the Mario Bros. if they pull the mushroom lever in an elevator in the royal palace, if they try to directly attack Ludwig von Koopa during one portion of the book, and if Mario pulls the wrong nob on the Koopaling's giant pipe organ.

Super Mario Bros. film
In the Super Mario Bros. film, a street vendor can be seen selling and advertising Fried Tweeter, apparently cooked Tweeters; instead of birds, the film portrays them as lizards. They are eaten on hotdog buns.

Mario Kart: Super Circuit
Tweeters made a small cameo in Mario Kart: Super Circuit. In Sunset Wilds, their likenesses are carved on two totem poles featuring it on the bottom, a Snifit in the middle, and a Shy Guy on the top. However, the Tweeter images appear to have their masks replaced with a beak and glasses, giving a closer resemblance to Toadies.

Super Mario World 2: Yoshi's Island
Tweeters were originally going to appear in Super Mario World 2: Yoshi's Island, but they were unimplemented in the final version of the game for unknown reasons.

Trivia

 * Tweeter's design may have been inspired by plague doctors' bird-like masks, which are still worn at the annual Carnival of Venice. Another source of inspiration may have been the Tengu, which are Japanese mythological creatures often depicted with long noses and red faces.
 * Despite being an enemy in Yume Kōjō: Doki Doki Panic, Tweeter did not receive artwork in the manual (or a name) until Super Mario Bros. 2. This is also the case for Spark and Flurry.