Table II.
Pigeons with their beaks longer than that of the Rock-pigeon, proportionally with the size of their bodies.
| Name of Breed. | Actual length of Feet | Difference between actual and calculated length of feet, in proportion to length of feet and size of body in the Rock-pigeon | |
| Wild rock-pigeon (mean measurement) | 2.02 | Too short by | Too long by |
| Carrier | 2.60 | .. | 0.31 |
| " | 2.60 | .. | 0.25 |
| " | 2.40 | .. | 0.21 |
| " Dragon | 2.25 | .. | 0.06 |
| Bagadotten Carrier | 2.80 | .. | 0.56 |
| Scanderoon, white | 2.80 | .. | 0.37 |
| " Pigeon cygne | 2.85 | .. | 0.29 |
| Runt | 2.75 | .. | 0.27 |
| Number of specimens | 8 | .. | 8 |
In these two tables we see in the first column the actual length of the feet in thirty-six birds belonging to various breeds, and in the two other columns we see by how much the feet are too short or too long, according to the size of bird, in comparison with the rock-pigeon. In the first table twenty-two specimens have their feet too short, on an average by a little above the tenth of an inch (viz. .107); and five specimens have their feet on an average a very little too long, namely, by .07 of an inch. But some of these latter and exceptional cases can be explained; for instance, with pouters the legs and feet are selected for length, and thus any natural tendency to a diminution in the length of the feet will have been counteracted. In the swallow and barb, when the calculation was made on any standard of comparison excepting the one above used (viz. length of body from base of beak to oil-gland), the feet were found to be too small.
In the second table we have eight birds, with their beaks much longer than in the rock-pigeon, both actually and proportionally with the size of body, and their feet are in an equally marked manner longer, namely, in proportion, on an average by .29 of an inch. I should here state that in Table I. there are a few partial exceptions to the beak being proportionally shorter than in the rock-pigeon: thus the beak of the English frill-back is just perceptibly longer, and that of the Bussorah carrier of the same length or slightly longer, than in the rock-pigeon. The beaks of spots, swallows, and laughers are only a very little shorter, or of the same proportional length, but slenderer. Nevertheless, these two tables, taken conjointly, indicate pretty plainly some kind of correlation between the length of the beak and the size of the feet. Breeders of cattle and horses believe that there is an analogous connection between the length of the limbs and head; they assert that a race-horse with the head of a dray-horse, or a greyhound with the head of a bulldog, would be a monstrous production. As fancy pigeons are generally kept in small aviaries, and are abundantly supplied with food, they must walk about much less than the wild rock-pigeon; and it may be admitted as highly probable that the reduction in the size of the feet in the twenty-two birds in the first table has been caused by disuse,[[312]] and that this reduction has acted by correlation on the beaks of the great majority of the birds in Table I. When, on the other hand, the beak has been much elongated by the continued selection of successive slight increments of length, the feet by correlation have likewise become much elongated in comparison with those of the wild rock-pigeon, notwithstanding their lessened use.
As I had taken measures from the end of the middle toe to the heel of the tarsus in the rock-pigeon and in the above thirty-six birds, I have made calculations analogous with those above given, and the result is the same,—namely, that in the short-beaked breeds, with equally few exceptions as in the former case, the middle toe conjointly with the tarsus has decreased in length; whereas in the long-beaked breeds it has increased in length, though not quite so uniformly as in the former case, for the leg in some varieties of the runt varies much in length.
As fancy pigeons are generally confined in aviaries of moderate size, and as even when not confined they do not search for their own food, they must during many generations have used their wings incomparably less than the wild rock-pigeon. Hence it seemed to me probable that all the parts of the skeleton subservient to flight would be found to be reduced in size. With respect to the sternum, I have carefully measured its extreme length in twelve birds of different breeds, and in two wild rock-pigeons from the Shetland Islands. For the proportional comparison I have tried with all twelve birds three standards of measurement, namely, the length from the base of the beak to the oil-gland, to the end of the tail, and from the extreme tip to tip of wings. The result has been in each case nearly the same, the sternum being invariably found to be shorter than in the wild rock-pigeon. I will give only a single table, as calculated by the standard from the base of the beak to the oil-gland; for the result in this case is nearly the mean between the results obtained by the two other standards.
Length of Sternum.
| Name of Breed. | Actual Length. Inches. | Too Short by | Name of Breed. | Actual Length. Inches. | Too Short by |
| Wild Rock-pigeon | 2.55 | .. | Barb | 2.35 | 0.34 |
| Pied Scanderoon | 2.80 | 0.60 | Nun | 2.27 | 0.15 |
| Bagadotten Carrier | 2.80 | 0.17 | German Pouter | 2.36 | 0.54 |
| Dragon | 2.45 | 0.41 | Jacobin | 2.33 | 0.22 |
| Carrier | 2.75 | 0.35 | English Frill-back | 2.40 | 0.43 |
| Short-faced Tumbler | 2.05 | 0.28 | Swallow | 2.45 | 0.17 |
This table shows that in these twelve breeds the sternum is on an average one-third of an inch (exactly .332) shorter than in the rock-pigeon, proportionally with the size of their bodies; so that the sternum has been reduced by between one-seventh and one-eighth of its entire length; and this is a considerable reduction.
I have also measured in twenty-one birds, including the above dozen, the prominence of the crest of the sternum relatively to its length, independently of the size of the body. In two of the twenty-one birds the crest was prominent in the same relative degree as in the rock-pigeon; in seven it was more prominent; but in five out of these seven, namely, in a fantail, two scanderoons, and two English carriers, this greater prominence may to a certain extent be explained, as a prominent breast is admired and selected by fanciers; in the remaining twelve birds the prominence was less. Hence it follows that the crest exhibits a slight, though uncertain, tendency to become reduced in prominence in a greater degree than does the length of the sternum relatively to the size of body, in comparison with the rock-pigeon.
I have measured the length of the scapula in nine different large and small-sized breeds, and in all the scapula is proportionally shorter (taking the same standard as before) than in the wild rock-pigeon. The reduction in length on an average is very nearly one-fifth of an inch, or about one-ninth of the length of the scapula in the rock-pigeon.
The arms of the furcula in all the specimens which I compared, diverged less, proportionally with the size of body, than in the rock-pigeon; and the whole furcula was proportionally shorter. Thus in a runt, which measured from tip to tip of wings 38½ inches, the furcula was only a very little longer (with the arms hardly more divergent) than in a rock-pigeon which measured from tip to tip 26½ inches. In a barb, which in all its measurements was a little larger than the same rock-pigeon, the furcula was a quarter of an inch shorter. In a pouter, the furcula had not been lengthened proportionally with the increased length of the body. In a short-faced tumbler, which measured from tip to tip of wings 24 inches, therefore only 2½ inches less than the rock-pigeon, the furcula was barely two-thirds of the length of that of the rock-pigeon.
We thus clearly see that the sternum, scapulæ, and furcula are all reduced in proportional length; but when we turn to the wings we find what at first appears a wholly different and unexpected result. I may here remark that I have not picked out specimens, but have used every measurement made by me. Taking the length from the base of beak to the end of the tail as the standard of comparison, I find that, out of thirty-five birds of various breeds, twenty-five have wings of greater, and ten have them of less proportional length, than in the rock-pigeon. But from the frequently correlated length of the tail and wing-feathers, it is better to take as the standard