Bird

Duskmourn: House of Horror Commander Tokens

Bloomburrow Commander Tokens

Modern Horizons 3 Tokens

Outlaws of Thunder Junction Tokens

Pride of the Clouds

Flying
Pride of the Clouds gets +1/+1 for each other creature in play with flying.
Forecast {2}{W}{U}, Reveal Pride of the Clouds from your hand: Put a 1/1 white and blue Bird creature token with flying into play. (Play this ability only during your upkeep and only once each turn.)

Flying
This creature gets +1/+1 for each other creature on the battlefield with flying.
Forecast — {2}{W}{U}, Reveal this creature from your hand: Create a 1/1 white and blue Bird creature token with flying. (Activate only during your upkeep and only once each turn.)

Dovescape

({WU} can be paid with either {W} or {U}.)
Whenever a player plays a noncreature spell, counter that spell. That player puts X 1/1 white and blue Bird creature tokens with flying into play, where X is the spell's converted mana cost.

({W/U} can be paid with either {W} or {U}.)
Whenever a player casts a noncreature spell, counter that spell. That player creates X 1/1 white and blue Bird creature tokens with flying, where X is the spell's mana value.