Bad weather, such as heavy rain, also forces birds to land. Since highs follow cold fronts, birds will be force to land immediately following the passage of a cold front. After the high has moved east, usually a day or two later, the birds have tailwinds and take off. On the right side of a high pressure system, the winds are coming from the north , so migrants land. The air around a high pressure center circulates clockwise .
Flags show direction wind is blowing from.
The reason is that low pressure systems often bring bad weather with them, so even though the winds may be right, flying conditions are not good. Check out the Current Surface Map and test your skills. Find the high pressure systems and look at the wind direction. These weather concepts can be very difficult to visualize.