Grass height management is an important tool as a wildlife hazard prevention strategy on airports. Different grass heights, mowing regimes, and grass species composition can attract varied groups of species representing different levels of risk for this kind of environment. Regular observations on thirteen airfields showed that birds were fewer and occurred less frequently on long grass (15 - 20 cm) than on short grass (5 - 10 cm) areas. The growing of long grass does not eliminate birds but generally reduces numbers and is therefore an effective component of bird control measures on airfields.