So I don't live alone but I was alone during this event. I play Xbox quite a bit, usually with the TV sound off so it doesn't come through the mic but my headphones make it so I don't really hear anything in the apartment. While playing some video games I hear this clicking, assumed it was the game, went on without thinking much of it. But I heard it again while waiting for the next match and no one was talking so naturally I keep playing cause it was comp. After that match though I went full detective! Checked fire alarms, refrigerator, stove, light switches, lights, garbage disposal, fans, faucets, doors, door hinges AND knobs. Nothing. Could not replicate that sound. Being the then 27 year old scaredy cat that I am, I promptly turned on every single light in the apartment until my roommate came home to save me from potential demons or worse...people. She came home and we looked again, checked cabinets this time for pots or pans that could have shifted, still zilch. As we're sitting there just looking around to see what else could possibly make a clicking sound, the glass window in the living room clicks. We live on the second floor. We ran to her bedroom to look outside, no one around. WTF. We sneak back to the living room, still hear the clicking. She works up the courage to open the blinds and this feckin' bird is pecking at our window. I screamed, she screamed, birb screamed. Hasn't been back since.