Birds that live and breed in vegetated coastal areas, such as dunes and small islands, not only build nests but also—unintentionally—shape their own surroundings. This was discovered by Utrecht-based Earth scientist Floris van Rees. He studied five uninhabited islands in the Dutch Wadden Sea region, comparable to the barrier islands off North Carolina and in the Chesapeake Bay, and observed how seabirds have a major impact on plant growth. "Plant species that retain sand better benefit from the presence of bird excrement, which in turn is beneficial for dune formation." This is particularly important now that sea level rise and coastal erosion are putting pressure on the habitats of many coastal birds.