Officials are taking other measures to keep the migration routes open.

Help scientists learn more about growth rates and migration routes.

However, because it is on a main migration route, many different birds can be seen here.

And other migration routes, it says, will have to be narrowed too.

It is important to keep these migration routes free of barriers.

This information will be then used to protect the birds' migration routes in the future.

This island chain is an important migration route for birds.

This area is a haven for bird life being on a major migration route north/south.

The river was used as a seasonal migration route by Indians.

The lake is located on a main north/south bird migration route.

That has blocked a popular migration route and driven people east.

The development will affect the migration route of the geese.

Much is still to be learned of marine feeding areas and migration routes.

The lower Potomac is a natural migration route, especially for water birds.

It must have been a migration route or something.

Will humanity know much more about itself if we plot out human migration routes?

He would follow the old migration route, the way the ancient hunters had gone when they followed game into America.

These include: geographic location, migration routes, language and political structure.

A bird observatory was set up in 1953 as the island is on important migration routes.

Is there a lack of suitable habitat along the migration routes?

Migration routes can cross roads; on the night of Sept.

Such disruption may also alter the migration route of this species.

But this year some of the normally crowded migration routes are nearly empty.

A shame, then, that the government is now squeezing these two migration routes so hard.

It also appeared that the migration routes of some fish were altered during the release.