A Mile And A Half A Minute

In 1900 an American pigeon flew 100 miles at the rate of 2,511.87 yards— nearly a mile and a half— per minute. Generally speaking, a bird has three types of flying speed — normal, accelerated or maximum (generally when chasing or being chased) and, in many cases, migration. A few other birds, for example the duck-hawk and golden eagle, sometimes also use the stoop or power-dive. Even within the same species considerable differences of flying speed are noticeable. Age, state of plumage, health and other physical factors modify a bird's powers of flight. One member of a covey of partridges has been observed flying at least fifteen percent faster than the others when all the birds were in full panic flight before a falcon. Ideally, therefore, any record that purports to represent the speed for any given species of bird under any one of the types of flying mentioned above should be for a bird in perfect condition. Fortunately for students of birds" flying speeds there are one or two timing methods available in which all the conditions I have mentioned can be met. And in the case of timing by aeroplane nearly all the conditions are fulfilled.

Timing by aeroplane is the most satisfactory method yet devised for obtaining the flying speeds of birds that cannot well be timed by laboratory methods. In France birds have been harnessed by silk thread to an indicator that recorded the amount of line taken out as the bird flew, and the time occupied. A simple calculation then gave the speed of the bird in miles per hour. The works of Marey, Houssay and Nagnan should be consulted for details of this method of timing. Another indoor timing method, used in England to find the pace of a bird shortly after it has risen from the sportsman's feet, was particularly ingenious. In a covered range, where no wind complications would be met, birds were made to fly forty yards, and then to pass through two screens made of very fine invisible cotton. The time taken was recorded by electrical chronograph (more accurate than a stopwatch!) and then the speed was worked out into miles per hour.

By this method it was found that partridges and pheasants, just after being flushed, attain a speed of about 30 miles per hour, the heavier bird—the pheasant — being slightly the faster. Incidentally, there is a generalisation that may be mentioned here: "The heavier the bird the slower it rises but the faster it flies." When a similar apparatus timed pigeons, the speeds varied between twenty-six and thirty-four miles per hour. An aviator, diving, reported that a duck hawk shot by him as though the airplane were standing still.

By: davidbunch

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