Unless you have a good-sized lawn, you’re more likely to see Western Bluebirds in a park with plenty of trees and plenty of bugs and worms. You’re also more likely to see them in breeding and nesting season, as they’ve busy with big demands on their food-gathering skills. WEBLs often build more than one nest before deciding the best spot to raise their young. Their main challenge is finding a cavity to nest in; since humans don’t like dead trees hanging around pristine parks, they’re usually removed — even dead branches that might afford an old Woodpecker hole. SFVAS provides nesting boxes in select SF parks and the WEBLs use them. Let us know if you’d like to hang a nest box or two.
Mountain Bluebirds (MOBL) as their name implies, are likely to be found in more elevated terrain.