Mayor Gardner noted that a lake that had served as a summer breeding ground for migratory cranes recently disappeared.
Demographic experts say Philadelphia is in the crosshairs of several unfortunate trends, both economic and migratory.
Were these birds visitors from the interior, or had they just arrived at the end of a migratory journey from some distant country?
Like most of the water-birds of America, the canvas-back is migratory.
North America; migratory at the northern limit of its range; roosting in colonies in winter.
Approximately all of the species concerned are of migratory habits.
Most antelope are not migratory, but in a few localities the flocks make a short migration.
Are they like the ducks, merely come, pause, and proceed on their migratory way?
In these migratory excursions, if they came to a brook or small river, their progress was not stayed.
They know that, without the migratory worker, most of the crops wouldn't get harvested.