The Conley II is highly effective against Starlings. Starlings have longer legs than martins and can't squat down low enough to enter. The Conley II is 98% effective at stopping starlings.
There is no entrance that can stop a house sparrow, they are too small and can slip thru any opening that a martin can slip thru.
If using the Conley Entrance in conjunction with a Troyer Tunnel you can use our Tunnel Trap which is very effective at catching those pesky house sparrows.