The wings of all rails are short and rounded. Their flight is not powerful, but can continue for long periods, and many species migrate annually. The weakness of their flight means they are easily blown off course, so they are common vagrants. This has led them to colonize many isolated oceanic islands. Furthermore, these birds often prefer to run rather than fly, especially in dense shrub or woodland habitats. Some are also flightless at some time during their moult period.