I have an elevator trap and it does catch sparrows but some reason more cardinals which I release immediately. In my back yard I use the sparrow sled from WCS and keep several in a large birdcage. When I get a call for sparrows in a building I take one from my cage and put it in the sparrow sled and take it to the store it is very effective. Particularly when there is a single lonely bird. The trap that HD linked to is also very effective in a building. It and the sparrow sled are both more effective coupled with the optional sparrow chirper. The trap door will also capture starlings and robins. The robin seldom gets in a building but dried mealworms are good bait for him. Starlings and sparrows both like bread and or millet seed. Or even water if there is none available. Apples and suet are also very good for starlings.
They want the starling gone and blood could be a problem due to customers. Due to his aggressiveness and coming close to customers a big bore blow gun with stun darts will temporarily disable him allowing you to grab him.
When purple martins are out of your area hang a 12 hole purple marten house near a tree as sparrows don't mind the tree but songbirds do. Put a mouse trap inside each hole. That can be hung in a barn year round. Very effective particularly during the mating season.
An accurate pellet gun, mist nets, and glue traps need to be in your tool box also.
My post went on a tangent primarily about birds in stores but I've done all this typing so I'm posting it.