Bee-eaters just like white storks have two main migration tracks. Birds from south-western Europe go through Strait of Gibraltar and directing to south fly through Sahara. They head for western Africa. Birds from eastern Europe go to southern Africa via Israel. When chicks grow up bee-eaters form large, even of over 120 birds, groups. Later these big herds divide into smaller ones. Birds encounter many difficulties and dangers during their journeys. Some are caused by people. There are countries where bee-eaters are being killed by bee-keepers who treat them as pests. Scientists estimate one out of three bee-eaters leaving Europe in autumn will come back in spring.