In fact there is a popular theory[1] that bird intelligence evolved because of the way their social structures work. Birds mate for life but they cheat. Every bird wants their partner to be loyal and itself to sex as many other birds as possible.

This means birds have to keep track of who can and can't see them cheat, who knows and who doesn't. There's even evidence that they rat each other out (2nd degree info) if they think there's a reward to be had. All of this requires immense intelligence, which happens to prove useful in other contexts.

There's also a bird species who does this with food caches. Easier to steal from others than to build their own so a plethora of deceptive tactics developed to ensure others can't see where you're storing those delicious nuts. Complete with fake caches, lying, and espionage.

[1] I learned about it in The Genius of Birds