In the world of Angry Birds, birds and pigs are natural enemies.
The pigs will stop at nothing to kidnap the birds’ eggs, and the birds are the only thing between the pigs and their lunch.
If they ever cross paths, fighting almost always ensues.
But in Angry Birds Stella, with no unborn children to protect or eat, birds and pigs have no reason to quarell.
In fact, the minion pigs are only ever hostile towards birds when directly ordered to attack by a higher-up such as Gale. Otherwise, they’re quite chill.
The birds aren’t hostile by default either, they mostly act in self-defense.
Additionally, In the show, each bird has their own little moments with the piggies:
One of the biggest examples of this improved relations between birds and pigs is Willow and Artist Pig's friendship.
Unfortunately, it's only relevant in 2 episodes. Would've been nice if we got to see more of them, but oh well.
The other bigger example is Season 2 Episode 1, where Stella tries to help the pigs after a certain event leaves them homeless.
Luca gets to play with some pigs (Season 1 Episode 5).
Luca not freaking out at the sight of pigs could be chalked up to his naivety, like his interactions with Gale, but the pigs don't react with any hostility at all either. They immediately let him come play in the mud with them, no ulterior motives or anything. Things only become somewhat of a problem when Luca wants to go to the castle with them, but even then they quickly decide "Yeah he's chill".
In Season 1 Episode 7, Dahlia recognizes that the pigs aren’t as useless as they seem, and tricks them to help with a project of hers.
Okay, this isn’t exactly "friendly" but here's how I can still defend my thesis statement:
Remember, we're comparing Angry Birds Stella's instances of Bird-Pig interaction with the ones from the rest of the Angry Birds franchise. Usually, cooperation is a big no-go, considering the whole child-eating thing. Even when they do team up, usually one or both parties are reluctant. However, when Dahlia discovers the pigs' talent here, she isn't like "Ah fuck, can't believe I gotta resort to THE PIGS!!!", instead she's joyous to discover a whole team of people who can help her; the fact that they're pigs does not matter in the slightest. Additionally, the only reason she has to trick them in the first place is because they are biologically hard-wired to be obident to the crown and only the crown.
As for Poppy, she is the exception, with 0 examples to her name.
She is a menace who cares for none, not even her fellow birds.
One possible exception to this improved relationship is the scene in New Day where the rest of Stella's flock, including Willow(!) immediately reacts negatiely to Stella taking in a lost pig.
Though there is a possible explanation: Stella is essentially inviting some random ass hobo to their place, usually a big no for most people.
Unfortunately, no rationalization can be made for the books, in which they're basically just racist for no reason.
One thing I wish happened is more bird pig coordination during the final parts of season 2. They were setting up the pigs turning against Gale during the late half of season 2, only for the pigs do fuck-all during the finale.