Birds' Migration Speed

The speed with which birds migrate varies with different species of birds and with the same species of bird in different parts of its journey. In general, birds travel faster during the latter I)art of their journey than during the first part. During the first part of March, the robin averages thirteen miles a day in migrating from southern Iowa to central Minnesota. From here its speed keeps increasing till it is traveling at the rate of seventy miles a day when it reaches Alaska by the middle of 1’1ay. The robins along the Atlantic Coast travel more slowly, at the rate of seventeen miles a day.

The average speed for all species of birds is twenty-three miles per day from New Orleans to southern Minnesota. From this locality some species travel northward at the rate of forty miles a day, and still farther north some at seventy-two miles, others at one hundred and sixteen miles, and five species, on arriving in Alaska, are traveling at the rate of one hundred and fifty miles a day.

The figures here given are for the species as a whole, not for individual birds. Usually birds migrate only a few hours during the night and then rest for a day or two, so that the average rate at which a species migrates is much less than for an individual bird. Our common small birds probably travel at the rate of about thirty miles an hour while migrating; ducks and geese may travel at the rate of forty-five miles an hour. Thus during a single night birds may travel from two hundred to four hundred miles.

Some birds migrate by day, some by night, and some both by day and night, but most are night travelers. The time selected by a bird for migration depends on its power of flight, its method of procuring food, and its disposition. The warbiers, vireos, and thrushes migrate by night, the swallows and hawks by day; while ducks, shore-birds, and sea-birds migrate both by day and night.

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