Falconer Adept

Whenever Falconer Adept attacks, create a 1/1 white Bird creature token with flying that's tapped and attacking.

Ordered Migration

Domain — Create a 1/1 blue Bird creature token with flying for each basic land type among lands you control.

Pride of the Clouds

Flying
Pride of the Clouds gets +1/+1 for each other creature with flying on the battlefield.
Forecast — {2}{W}{U}, Reveal Pride of the Clouds 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.)

Soul of Migration

Flying
When Soul of Migration enters the battlefield, create two 1/1 white Bird creature tokens with flying.
Evoke {3}{W} (You may cast this spell for its evoke cost. If you do, it's sacrificed when it enters the battlefield.)

Mu Yanling, Sky Dancer

+2: Until your next turn, up to one target creature gets -2/-0 and loses flying.
−3: Create a 4/4 blue Elemental Bird creature token with flying.
−8: You get an emblem with "Islands you control have '{T}: Draw a card.'"

Eyes in the Skies

Create a 1/1 white Bird creature token with flying, then populate. (Create a token that's a copy of a creature token you control.)

Scion of Vitu-Ghazi

When Scion of Vitu-Ghazi enters the battlefield, if you cast it from your hand, create a 1/1 white Bird creature token with flying, then populate. (Create a token that's a copy of a creature token you control.)

Roc Egg

Defender (This creature can't attack.)
When Roc Egg dies, create a 3/3 white Bird creature token with flying.

Wingmate Roc

Flying
Raid — When Wingmate Roc enters the battlefield, if you attacked this turn, create a 3/4 white Bird creature token with flying.
Whenever Wingmate Roc attacks, you gain 1 life for each attacking creature.

Akim, the Soaring Wind

Flying
Whenever you create one or more tokens for the first time each turn, create a 1/1 white Bird creature token with flying.
{3}{U}{R}{W}: Creature tokens you control gain double strike until end of turn.

Scour the Desert

Exile target creature card from your graveyard. Create X 1/1 white Bird creature tokens with flying, where X is the exiled card's toughness.

Alrund's Epiphany

Create two 1/1 blue Bird creature tokens with flying. Take an extra turn after this one. Exile Alrund's Epiphany.
Foretell {4}{U}{U} (During your turn, you may pay {2} and exile this card from your hand face down. Cast it on a later turn for its foretell cost.)

Rukh Egg

When Rukh Egg dies, create a 4/4 red Bird creature token with flying at the beginning of the next end step.

Ornitharch

Flying
Tribute 2 (As this creature enters the battlefield, an opponent of your choice may put two +1/+1 counters on it.)
When Ornitharch enters the battlefield, if tribute wasn't paid, create two 1/1 white Bird creature tokens with flying.

Dovescape

({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.

Battle Screech

Create two 1/1 white Bird creature tokens with flying.
Flashback—Tap three untapped white creatures you control. (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Jötun Owl Keeper

Cumulative upkeep {W} or {U} (At the beginning of your upkeep, put an age counter on this permanent, then sacrifice it unless you pay its upkeep cost for each age counter on it.)
When Jötun Owl Keeper dies, create a 1/1 white Bird creature token with flying for each age counter on it.

Swan Song

Counter target enchantment, instant, or sorcery spell. Its controller creates a 2/2 blue Bird creature token with flying.

Skycat Sovereign

Flying
Skycat Sovereign gets +1/+1 for each other creature you control with flying.
{2}{W}{U}: Create a 1/1 white Cat Bird creature token with flying.

Ominous Roost

When Ominous Roost enters the battlefield or whenever you cast a spell from your graveyard, create a 1/1 blue Bird creature token with flying and "This creature can block only creatures with flying."

Seller of Songbirds

When Seller of Songbirds enters the battlefield, create a 1/1 white Bird creature token with flying.

Emeria Angel

Flying
Landfall — Whenever a land enters the battlefield under your control, you may create a 1/1 white Bird creature token with flying.

Migratory Route

Create four 1/1 white Bird creature tokens with flying.
Basic landcycling {2} ({2}, Discard this card: Search your library for a basic land card, reveal it, put it into your hand, then shuffle.)

The Raven's Warning

(As this Saga enters and after your draw step, add a lore counter. Sacrifice after III.)
I — Create a 1/1 blue Bird creature token with flying. You gain 2 life.
II — Whenever one or more creatures you control with flying deal combat damage to a player this turn, look at that player's hand and draw a card.
III — You may put a card you own from outside the game on top of your library.

Ravenform

Exile target artifact or creature. Its controller creates a 1/1 blue Bird creature token with flying.
Foretell {U} (During your turn, you may pay {2} and exile this card from your hand face down. Cast it on a later turn for its foretell cost.)