|
back in 24 hours, a distance of 200 miles direct and 390 miles by the nearest sea route. Finally, some of the Skokholm shearwaters were taken by air to Venice. The interesting point about this experiment is that the Mediterranean is outside the normal range of the Manx shearwater. The distance was 930 miles direct, and 3700 miles by nearest sea route. Yet one of the birds got back in 14 days. As far as many land birds are concerned, we have similar striking evidence of this homing instinct. Swallows which were nesting at Bremen, Germany, were taken by air to Croydon, a distance of 428 miles, and there released. The first birds were back within 4 days. The same investigator was able to show that swallows would return to Berlin from London, Munich, Venice and Athens. Red-backed shrikes got home to the Berlin area from Marseilles ; wrynecks from Munich, Venice and Salonica. There is a certain amount of evidence, however, that the homing instinct is not equally powerful in all species of wild bird, and it appears that some sedentary types may not possess it in any marked degree. Thus the goshawk, a resident species which does not normally stray far from its native forests, appears to have little or no ability to find its way back from long distances. The American counterpart of our sparrow-hawk, known as the sharp-shinned hawk, did not return home even from a distance of a few miles. |
