A comparative analysis of migratory adaptations was made with the examples of the Rustic Bunting
Emberiza rustica which migrates to Siberia across the Japan Sea and the Black-faced Bunting
Emberiza spodocephala which moves only along Japanese coast. These birds struck at the lighthouse of Hegura I., off Noto Penisula, Honshiu, on same dates in April, 1963 and 1964. The Rustic Bunting showed the following higher migratory adaptations than the Black-faced:
1. The body weight was heavier having much more fat, but fat-free body weight was about the same, and the body length without tail length and the trunk length (shoulder tip to cloaca) were also the same.
2. Wing length and wing span were larger, with the pointed wing tip and larger Kipp's wing-index, and the secondaries part was narrower.
3. The wing area was slightly larger and, while the primaries and seconderies areas were same in the Black-faced Bunting, the primaries area was larger in the Rustic with the expense of the seconaries area.
4. The average wing bredth was smaller, while the aspect ratio and the wing loading were larger.
5. The tail was strait, shorter and a little forked and concave, with the smaller tail area (when spread 45 degrees) and larger tail loading. These are adaptations for smooth air flow and effective tail function while migrating.
6. Had slightly longer keel of the sternum. The humerus was of the same length as that of the Black-faced, but the ulna and especially the hand bones were elongated. This caused the pointed wing shape and somewhat longer inner secondaries and tertiaries, and each wing quill was not necessarily longer than that of the Black-faced.
7. The leg bones were shorter and thinner and the total leg weight was lighter, with slightly more slender tibial muscles.
8. The fat weight was nearly twice as much as that of the Black-faced. The fat amount taken by hand was a little less than twice of that extracted by Soxlet apparatus from the whole body including tissue lipids.
9. The liver, heart and lung were slightly larger in a few material examined and the intestine was longer. These data however need confirmation.
10. The head (skull) was smaller in measurements and weight than that of the Black-faced.
11. The material used in this study had been preserved by Ishizawa's method (Tori No. 81, 1963) of weak formalin injection and remained in semi-fresh condition even after more than 200 days (Table 8). However slight change of weights should have been innevitable.
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