Abstract: A trapdoor for a birdhouse, particularly one constructed to attract purple martin birds, so as to trap in a compartment of the house species of undesirable birds, such as sparrows. The door includes an opening to permit the undesirable birds to enter a compartment of the birdhouse. A pivotal gate is secured to the door behind the opening and is retained by a trigger mechanism in an unblocking position above the opening. When a bird enters the compartment through the opening and alights on the trigger mechanism, the gate is released and drops by gravity across the opening to trap the bird within the compartment. The trapdoor includes structure for positively locking the gate against inadvertent pivotal trapping movement should the birdhouse or trapdoor be moved or displaced.

Abstract: A locking device for releasably securing a birdhouse upon its mounting pole. A locking plate secured to the bottom of the birdhouse has an opening through which the mounting pole is passed. The plate opening is larger in diameter than the outside diameter of the post. The plate is biased into a locking position at an angle relative to the axis of the post. A pivotal bracket is operable on the plate to bias the plate to a horizontal release position normal to the axis of the post. A lanyard secured to the bottom of the birdhouse is passed up the pole around a pulley wheel at the top thereof and returned down the pole through the bracket. A free end of the lanyard extends below the bracket. Pivoting of the bracket and resultant release of the locking plate is accomplished by pulling on the free end of the lanyard at an angle relative to the post to move the locking plate to its release position.