46 THE ZOOLOGIST. 



from a bird on Eyebroughty, the flock would have gone out 

 to sea. It is, therefore, probable that in the flights to Eye- 

 broughty the landmarks passed on the way are not recognised. 



The second result of the observations approaches the problem 

 of the second component. The Oystercatchers did not venture 

 to follow the direct " oversea" route from Aberlady Bay, as they 

 always do in clear weather. The fog would have hidden them 

 from the land for the whole of the journey — a distance of nearly 

 three miles — and they would have been compelled to direct 

 themselves with sufficient accuracy to strike a rock which has a 

 breadth of only fifty yards. Instead they followed the coast- 

 line, there is every reason to believe. It is true they were 

 known to do so only as long as their calls were audible. But 

 previous fragmentary observations made at several points 

 further west render it probable that in fog the birds hug the 

 coast the whole way. When the return journey was begun 

 the birds turned westward correctly, and without hesitation on 

 striking the coast of the mainland. They knew that Aberlady 

 Bay lay to the west. But their means of keeping a true course 

 was not sufficiently adjusted to enable them to proceed in fog on 

 the direct course over the sea. The observations on the Geese 

 tend to confirm this conclusion. On reaching the shore the 

 Geese changed their direction of flight to the westward, and 

 showed a general knowledge of the position of Aberlady Bay. 

 On the assumption that the new direction of flight was correctly 

 observed, there was, however, a difference of 45° between the 

 magnetic course taken by the Geese and the magnetic bearing 

 of Aberlady Bay. 



From these observations we may grant the birds had at least 

 a constant knowledge of the general whereabouts of the place or 

 places to which they were impelled to go. A knowledge of land- 

 marks was not acquired, though such were available on many 

 occasions. The means of correcting drift was not adequate in 

 fog. On the other hand, the observations throw no light on the 

 use or disregard of the objective as a guide when that is possible. 

 Nor do they clear up the nature of the mechanism of the first 

 and second components. On these matters further information 

 is required. 



A Canary which had the liberty of a room was in the habit 



