The invention comprises a structure that affixes over the entrance hole of an avian cavity nest and serves to discriminate between prospective nesting birds by virtue of having the entry diverted to a vertical entranceway with the access on the lower end. The prospective bird must pass up through the structure to gain access to the entrance hole of the nest cavity.

A birdhouse entrance is provided with an entrance opening having two posts projecting vertically from the bottom edge of the opening toward the top edge. The two posts are spaced apart such that a bird of selected size cannot pass between them without opening its wings. Sufficient clearance for the wings is provided between the outer edges of the posts and the side edges of the entrance opening.

The present invention is directed to a shield capable of inhibiting squirrels from eating bird seed from a bird feeder. The present invention comprises an enclosure having a cavity capable of housing bird seed, a perch attached to the enclosure and located below the hole, and a shield located offset from and substantially in front of the hole and in proximity to the perch. The shield preferably has three substantially U-shaped members capable of inhibiting squirrels from eating the bird seed through the hole. A structure is preferably attached between the enclosure and the shield to secure the shield in its offset position, and preferably comprises a first segment attached between the first and second terminal ends of the first U-shaped member, and a second segment attached between the first and second terminal ends of the third U-shaped member. These first and second segments further inhibit a squirrel from accessing the hole in the bird feeder. The bird feeder optionally also comprises a canopy attached to the enclosure and located above the hole and in proximity to the shield. The canopy further inhibits squirrels from eating the bird seed through the hole, as well as substantially protects the hole from rain.

A modular birdhouse in accordance with the present invention includes a support pole, a collar, at least one wire form and at least one nest module. First, the collar is slidably connected to the pole. The wire form has a square shape, and the ends of the wire form are upturned and inserted into corresponding openings in the collar. The collar includes coordinated flanges with fasteners that fix the wire forms to the collar. Two or more collars can be interconnected in a stacked manner to create tiers of nest modules. Each nest module has a plurality of connector slots. For attachment, the nest module is positioned within the square shape of the wire form and then rotated until the connector slots of the nest module engage the wire form. A porch structure interconnects the wire form to the nest module to prevent further rotation and disengagement of the nest module. Nest modules may be added or removed from the wire forms as desired by the operator and without the use of tools and/or implements.