A compost is a good way to dispose of bird droppings and many other things we need to discard. Grass clipping, weeds, leaves from the fall, etc. Any organic matter will compost and become a very good fertilizer for the lawn and garden. Here is a diagram of the one I use.

Constructed from 2 X 2 pressure treated pine, 3/8" mesh plastic chicken wire a few #10 x 3" screws and wire ties. The red lines indicate 10" long cuts in the mesh. When it's time to remove some of the compost the front bottom wire ties are cut so the section of mesh can be lifted. The wire ties are used to hold the chicken wire to the 2 X 2 frame. They will not rot or rust as most staples would and are easily removed for repairs.
For a cover a 4 ft. x 6 ft. fiber reinforced polyethylene tarpaulin is tied to the back with wire ties and around the top with a rope.

The total cost other than 4 hours labor is about $25.00.
For More information on composting go to this site.