In our study the definition of long distance dispersal was related to typical small-scale farming patterns in alpine regions. Due to crop rotation maize is usually not grown in fields next to each other but are separated by other crops with separation distances of more than 50 m. According to an analysis of aerial photos of an eastern region in Switzerland the distance between maize fields varied from 75 to 149 m, with an average of 112 m (Flury et al., 2004). Therefore, our analysis of pollen dispersal focused on distances between 50 and 4500 m.