16 MICHIGAN BIRD LIFE. 



The matter of size cannot be too strongly insisted upon. In the common 

 mind the small hawk or duck or swallow is merely a young individual of the 

 same kind as the larger ones about it, yet in nine cases out of ten this assump- 

 tion is entirely wrong. Sportsmen talk constantly and confidently of very 

 large woodcock or partridges or ducks, their idea of size being based upon 

 weight. It is perfectly true that a woodcock or duck when fat and in what 

 is called good condition will weigh from one-third to one-half more than the 

 same bird when thin. Yet the measurements of total length, expanse of 

 wings, single wing, and tail will remain absolutely the same whether the 

 bird be thin or fat. Of course there is often a wide difference in size, as well 

 as in weight, between the male and female of the same species, and certain 

 birds, for example grouse and ducks attain their full size much more slowly 

 than the average small bird, such as the sparrow or thrush. In the case of 

 the latter birds the ability to fly is acquired only when almost full grown, and 

 as stated before they become as large as their parents within two weeks 

 after leaving the nest. 



A certain amount of variation nevertheless does exist among birds even 

 when those of the same age and sex are considered. This is known as "in- 

 dividual variation " and is usually confined within narrow and pretty definite 

 limits. As a rule such variation does not exceed ten per cent of the average. 

 Thus if the average length of a bird is six inches the extremes would be from 

 about 5.7 to 6.3, and the same rule would apply to measurements of wings, 

 tail, beak and feet. The total length of a bird can be obtained accurately 

 only from the bird itself before it has been skinned, or as we say "in the 

 flesh." It is taken by laying the bird upon its back upon a table, taking 

 the beak in one hand and the feet in the other and stretching the specimen 

 hard enough to take all the curves out of the neck and back. While in this 

 position the distance between tip of bill and tip of tail gives the measurement 

 known as total length. Another measurement often taken from the fresh 

 specimen is known as "extent of wings" or spread of wings. This is found 

 by first thoroughly relaxing both wings by opening and closing the joints, 

 and especially the shoulder joint, after which the bird is placed upon its 

 back and with one hand holding each wing by the carpal or wrist joint the 

 wings are spread as far as possible and at right angles to the body. While 

 in this position the distance from wing tip to wing tip is called extent of wings 

 or spread of wings. Obviously the two measurements just described can 

 be taken only from the fresh specimen and only an approximation 

 can be made from the dried skin or the mounted bird. Careful collectors 

 are supposed to take both these measurements and record them on 

 the label tied to each skin, but for various reasons, largely lack of time, this 

 is not always done. Hence the measurements on which the student must 

 depend are those which are practically the same in the skin as in the fresh 

 bird. It is found that little change takes place in the length of bill, feet,, 

 wings, or tail in drying, and hence measurements of these parts are more 

 commonly used and give better satisfaction. Four measurements are con- 

 stantly used in the keys and descriptions in this work and it is important 

 therefore that the student should understand exactly how these are 

 taken. First, length of wing or simply "wing." This is obtained from 

 the closed wing by slipping a scale beneath the wing, placing one end of the 

 scale exactly at the tip of the wing and marking the point reached by the 

 shoulder or main bend of the wing in front. A better way, especially for 

 small birds, is to use a pair of compasses, but the measurement should always 

 be taken from below, being in fact the chord of the curved wing. The figure 



