Veil of Birds

When an opponent casts a spell, if Veil of Birds is an enchantment, Veil of Birds becomes a 1/1 Bird creature with flying.

Skycloud Expanse

Soulcatchers' Aerie

Whenever a Bird is put into your graveyard from the battlefield, put a feather counter on Soulcatchers' Aerie.
Bird creatures get +1/+1 for each feather counter on Soulcatchers' Aerie.

Plains

Coast Watcher

Island

Mystic Familiar

Flying
Threshold — As long as seven or more cards are in your graveyard, Mystic Familiar gets +1/+1 and has protection from black.

Storm Crow

Flying (This creature can't be blocked except by creatures with flying or reach.)

Crookclaw Elder

Flying
Tap two untapped Birds you control: Draw a card.
Tap two untapped Wizards you control: Target creature gains flying until end of turn.

Celestial Gatekeeper

Flying
When Celestial Gatekeeper dies, exile it, then return up to two target Bird and/or Cleric permanent cards from your graveyard to the battlefield.

Warden of Evos Isle

Flying
Creature spells with flying you cast cost {1} less to cast.

Skyshroud Falcon

Aven Cloudchaser

Flying (This creature can't be blocked except by creatures with flying or reach.)
When Aven Cloudchaser enters, destroy target enchantment.

Duskrider Falcon

Airborne Aid

Draw a card for each Bird on the battlefield.

Gustcloak Savior

Flying
Whenever a creature you control becomes blocked, you may untap that creature and remove it from combat.

Bay Falcon

Suntail Hawk

Arctic Aven

Flying
Arctic Aven gets +1/+1 as long as you control a Plains.
{W}: Arctic Aven gains lifelink until end of turn. (Damage dealt by this creature also causes you to gain that much life.)

Zephyr Falcon

Serra Aviary

Soulcatcher

Flying
Whenever a creature with flying dies, put a +1/+1 counter on Soulcatcher.

Stormscape Familiar

Flying
White spells and black spells you cast cost {1} less to cast.

Treetop Sentinel

Island Sanctuary

If you would draw a card during your draw step, instead you may skip that draw. If you do, until your next turn, you can't be attacked except by creatures with flying and/or islandwalk.

Thieving Magpie

Flying (This creature can't be blocked except by creatures with flying or reach.)
Whenever Thieving Magpie deals damage to an opponent, draw a card.

Keeper of the Nine Gales

Flying
{T}, Tap two untapped Birds you control: Return target permanent to its owner's hand.

Aven Smokeweaver

Sage Owl

Flying
When Sage Owl enters, look at the top four cards of your library, then put them back in any order.