Birds marked as adults present further problems, but also provide interesting evidence. Hooded crows, captured on migration in spring at Rossitten and then released, have been recovered in autumn actually in the same place and in other localities in Germany, and one marked in October was taken two years later, in spring, in Finland. The sum of these records of crows proves one thing conclusively--the fallacy of Gätke's due east to west and west to east flight, and supports a coastwise migration for this species. Adult teal, captured in decoys, ringed and released in South Denmark in September and October, were taken in November and December in Hampshire, Suffolk and the Moray Firth, whilst others from the same place were recorded from other parts of England and Ireland, from western France, Holland, the south of Spain and the north of Italy. Fly-lines, if followed, are divergent and complicated. Four young herons were marked in one nest in Denmark; one was recorded in Holstein in June, and another in Mecklenburg in July; the third was killed near Salisbury in Wiltshire in October, and in the following February the last was obtained in the north-west of France. Two from another nest were recovered in Denmark, one in July and the other in February, twelve months after birth. Another heron reached Andalusia by August. In each case where there was indication of a direction it was south-westerly. Many more records might be mentioned, but these are sufficient to show the value of the method and the present insufficiency of results. Many of these records show that the speed of the migrating birds, even in spring, is not great. Mr Cooke proves that most species in North America travel slowly through the districts where food is plentiful and during the earlier part of the journey northwards only a few miles are covered per day; they travel with the slowly advancing vernal wave, but, as we shall show in the next chapter, many species actually outstrip it, and travel from warmer to colder climates. [Illustration: Map showing the range of the American Golden Plover, with its known migration route. (From _The National Geographic Magazine._)]