An accidental but very useful tool in keeping track of bird migrations into and through Texas is NexRad; ”next generation radar”. NexRad is blind to non-moving objects (like buildings, towers and a mass of birds sitting on trees in a forest). Nor does it pick up very low objects (insects, dust, smoke, and most local birds). To be visible on radar, bird flights must be above roughly 350 feet. This covers migratory flight very well.
An increasing number of TV stations are doing this during the spring migration.
In general birds flying over the
Gulf (where almost all mass migration takes place) fly at several thousand feet
above the water. Birds migrating over land fly lower (1000 ft. or less). Storms
or unseasonable cold sometimes mean that migrating birds aim for land sooner
than normal (hitting Corpus Christi rather than Galveston for example) so they
can stop and rest. Still, many migrating birds perish over the open waters.