There aren't many plants where bird droppings will drop completely through the leaves and flowers so that there is no sign of it. There are many, however, that camouflage the spots, some better than others. Plants with white spots, white stripes, or white variegation on their leaves or masses of white flowers will mask the bird droppings. Here is a list of possibilities. Perennials Aegopodium podagraria 'Variegatum' — Bishops Weed. This has splotches of white. 6" (inches) tall. Sun to part shade. Note: This plant may spread very vigorously and become difficult to control. Arrhenatherum elatus 'Variegatum' — Bulbus Oat Grass. White and green striped. 8 to 12". Sun. Artemesia 'Sun King', 'Silver Queen', 'Silver Mound'. Silvery foliage 1 to 1 1/2' (feet) tall. Sun. Artemesia schneidrana — Angels-hair wormwood. Silvery foliage 1 to 1 1/2' tall. Sun. Athyrium nipponicum — Japanese Painted Fern. 'Silver Falls'. Silvery fronds. Shade. 18" high. Brunnera macrophylla — 'Jack Frost'. Silver leaves with green veins. Light shade. 12 to 15" tall. Cerastium tomentosum — 'Snow in Summer'. Silver foliage with flowers late in spring. 6" high. Sun. Hosta, variegated. There are many cultivars of white/green hosta such as 'Fair Maiden'. Part shade. 1 to 3' tall. Lamium maculatum — Spotted Dead Nettle. 6 to 10" tall. Part shade. Phalaris arundinacea — Ribbon Grass. 'Picta' 2 to 3' high with green and white stripes. Can be invasive; use edging. Or 'Feeseys Form' has more white in the blades and is not invasive. Polemonium — Variegated Jacobs Ladder. 'Snow and Saphhires'. This has white on the leaf edges. 6" high. Part shade. Pulmonaria saccharata — Lungwart. 'Bethlehem Sage'. This has white-flecked foliage. Part shade. 9 to 18" tall. Annuals Caladium — 'White Christmas' or 'White Queen'. This has large white leaves with green veins. White Queen has a pink center. 18 to 21" tall. Shade. Petunia — 'Pearly Wave' 6" high; 'Frillytunia' 10 to 12" high; 'Tidal Wave' 10" high. All have masses of white flowers all season long. Sun. Other You might also consider a rock ground cover such as light-colored pea gravel or white granite stone over landscape cloth. You would need 2 inches in depth. This has the advantage of being easy to clean by just hosing it off. Also, all bird droppings are not alike! Some birds (starlings) have messy white droppings, while others are "more petite" in their excretions. Changing the type of bird feed you use, or the type of feeder, will affect the species of birds that visit your feeder. Try experimenting.