Bird's Diet

Bird’s diet is almost exclusively insects. The most common kinds of food are caterpillars, spiders, and grass­hoppers. Some birds feed fruit to their young, the kingfishers feed fish,and hawks and owls feed mice and other rodents.

Large insects are frequently broken into smaller pieces by the parents before being fed to the young. Some birds, like the hummingbird and flicker, feed their young by regurgitation. The food is first par­tially digested in the crop or stomach of the parent bird and then fed to the young by the parent bird's inserting its bill far into the mouth of the nestling. As a prevention against overfeeding, young birds have an instinctive response in the throat. The parents place the food in the throat, and if the gullet is already full, the throat does not respond, and the parent removes the food and puts it into the throat of another, till one is found which does respond.

Cleaning the nest. Another duty of the parents is to keep the nest clean. The excreta of the young are voided in membranous sacs, and these are either removed by the parent or swallowed.

Brooding. During hot days birds may frequently be seen brooding their young. They stand with spreading wings and tail shielding the young from the sun's rays, often themselves panting with wide­opened bills. During hot days this may occupy a large portion of the bird's time, the bird sometimes remaining for a period of forty minutes without leav­ing. In the same way the birds may protect their young from rain.

A house wren's day. In order to give some idea of the activities of birds while rearing their young, the following account of a day's observations of a pair of house wrens is given.

During the summer of 1993 the class in nature­study at the Mankato State Normal School kept a detailed record for one day of the feeding activities of a pair of house wrens which reared their young in a nesting-house located on the writer's grounds. The class was divided into ten sections and each section watched the birds for an hour and a half. The young wrens were two days old. The day was a typical, clear summer day with the temperature 67 degrees at 4 o'clock A.M. In the afternoon there was a heavy shower.

The observations began at 4 A.M., a half-hour be­fore sunrise, and extended till 8.20 P.M., a half-hour after sunset. The birds began to feed their young at 4.36, three minutes before sunrise, and continued till 7.58, thirteen minutes after sunset, thus making a working day of fifteen hours and twenty-two min­utes. At the end of the day the records were summar­ized with the following results: The young birds were fed two hundred and thirty-eight times, two hun­dred and eighteen by the female, eighteen by the male, and on two visits the sex was not deter­

The longest time between any two consecutive feedings was twelve minutes, except during the shower, when a period of sixteen minutes elapsed. The shortest time between two consecutive feedings by the same parent was one half-minute. The male was singing most of the day. Frequently he sang with an insect in his closed bill, sometimes waiting several minutes before feeding the young. Three times during the day he drove away a red squirrel, and once another wren. During the remainder of the time that the young were in the nest, they were watched occasionally from day to day for short periods, with the follow­ing results: ­

When the young were fourteen days old, the birds were watched for four hours at different times of the day, showing an average of nineteen and three fourths feedings per hour. For the day of fifteen hours, this would mean three hundred and three times per day. Taking the average between this and two hundred and thirty-eight, the times the young were fed when two days old, we get two hundred and seventy times as the average number of times the young were fed daily during the period they were in the nest. Mul­tiplying this by fifteen, the number of days the young were in the nest, gives four thousand and fifty as the total number of times the young were fed.

All the parent often brought more than one insect at a visit, the rearing of this wren family meant the destruction of from four to five thousand insects.

The largest number of times the young were fed in an hour was twenty-five, immediately after a storm when the young were twelve days old. The smallest number of times was eight during a heavy shower when the birds were two days old.

During the first days of rearing the young, most of the feeding was done by the female alone, but later more assistance was given by the male, until on the last day the work was about equally divided be­tween them.

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