would be possible to paint them white and make them seagulls
Cute idea I will put it on my nice to have list.
Something quite similar, that came to my mind, is a bevy of crows being startled up from a forest tile once in a while, when a party comes to close, to vanish on another forest tile in the distance.
As for the tavern ( http://battlebrothersgame.com/wp-content/uploads/2016/02/tavern_folks.jpg ), since it is accessable day and night, I thought there could be different folk in front of it at night. Maybe something like: guys doing shady business(a hooded figure hands another hooded figure a pouch of coin), a drunk guy peeing against one of the barrels/the wall, a guy throwing up, a passed-out guy lying on the floor or leans sitting against the wall, a beggar sitting next to the door begging for a donation(with someone trying to drive him away), two guys brawling, a guy and a woman departing with on arm around each other, a broke guy being kicked out, two people kissing, a woman sitting on the lap of a man, two people sway to and fro with their mugs raised bawling out a drinking song.
And maybe the mercs/daytalers for hire could sometimes hang out at a fountain, or a statue lest they do not appear to be so out of place or right in the way of people that have business to do. Additonally there sometimes could be a (fat) merchant(someone that clearly is not part of the guys, that want to be hired) talking to some of them, negotiating conditions or guards telling them to move elsewhere.