My 11-year old male cat has, for about the past 5 years or so has been going through our closet and drawers in the basement dragging out socks, gloves, hats, etc. every night. While he's doing this though he is howling very loudly. every morning i come downstairs and there's always something he dragged out on the floor. When I stay up late every now and then I catch him dragging these things out to our living room, howling, drops them in the middle of the floor comes over to me, while still howling, and rubs against my leg. any idea on why he does this?