I know such cities. Even some Vietnamese tropical cities aren't that joyful from the point of birdscape. Probably, it's about century-old parks + how many trees with edible fruits grow (including cones and seeds) + how many dead / half-dead trees are left in parks without attention (often they are removed for numerous reasons), how many places for nesting in the city... Quite interesting topic - what defines the birdscape of a city.