Electrical switch for porch light only works when nearby receptacle is in use.?

have a switch plate with 2 switches by my front door, a switch for the porch light and a switch for the entryway chandelier (the chandelier also has a second switch at the top of the stairs). Around the corner from the switches is a wall socket. Neither the porch light or chandelier work, unless something is plugged into the wall socket. This problem is intermitant over the long term meaning, the lights will work fine for a month or 2 and then have the problem a similar time. I tested the wall socket with plug-in tester and it shows correct wiring. I will also note, 2 seasons ago a bird built a nest in and around the porch light socket with some nest fibers getting into the bulb screws hole. This was the first occourance of the problem. When I cleaned out the nest, everything worked fine for a while and then the problem started again. The porch socket looks clean and work fine so long as there is something plugged into the inside socket. What could be causing this problem?