Purple Martins are very sociable. After nesting, they gather in large numbers in martin ‘roosts’ as they prepare to migrate to South America for the winter. These roosts can be very large, some approaching 1 million birds.
Martin Roost locations
Martin roosts are often located near large bodies of water, sometimes on islands or large bridges.
Not all roosts are near water, and can even be found in shopping mall parking lots.
Once a roost area has developed, it tends to be used year after year.
The Purple Martin Conservation Association maintains a list of known roosting locations.
Purple Martins also form communal roosts on their South American homes, although they tend to be centered around city parks and similar habitats.