House Martins nest under the eaves of houses and (because they like to live in colonies) very often multiple pairs will take up residence in the same location. As the droppings from a number of birds can be a bit of a nuisance on the ground below we have developed a dropping board to help catch unwanted mess. Simply screw the board about 60cm below the House Martin nest or colony. A special opening between the wall and the dropping board means it is impossible for them to build new nests below the shelf and this opening will also provide a sheltered area for bats.