406 Mr. J. II. Gurncy on the 



birds, especially small birds, would be exposed to considerably 

 more danger by day than by night, from Hawks and Gulls, 

 and even from man. 



So far as the Mediterranean is concerned, the fact that 

 most birds migrate bj night is not a sufficient proof, as some 

 have alleged, that they do not travel by sight, a sense which 

 is known to be very highly developed in them {Gyps fulvus 

 and Cyjjsekis opus for example), for unless the night were 

 foggy or exceptionally dark, coast-lines and mountains would 

 be visible. They probably have greater powers of seeing 

 in the dark than we have ; and supposing a Corn-crake or 

 a Turtle-Dove nearly half a mile up in the air, which 

 is no unreasonable altitude, to approach the coast-line of 

 Provence, no doubt some of the island of Corsica would 

 be visible to it, and the contour of a portion of the Italian 

 coast ; nor would it on starting have flown many miles 

 from Algeria before either Sardinia or the Balearic Isles 

 came into view. 



If we look at the map, it is evident that there is hardly 

 any part of the Mediterranean Sea where a migratory bird, 

 crossing on a fine night, need be out of sight of land for 

 more than three or four hours, and during that time its 

 sense of direction would keep it pretty much in the course 

 it had been taking when it started. 



Now as to the time required for the transit. Under 

 favourable circumstances it could not take a Turtle-Dove 

 more than 11 hours to fly from Algiers to the Var — that is, 

 at the rate of 37 miles an hour, which is what Mr. Tegetmeier 

 tells us that a Homing-Pigeon has been actually known to 

 attain ; but supposing a strong wind to blow directly behind, 

 it would perhaps do the voyage in half that time ; more- 

 over, a Homing-Pigeon does not fly straight, but generally 

 describes large curves. 



It is almost certain that the greater part of the spring- 

 migrants — practically all which are not delayed — can cross 

 the Mediterranean in its broadest part in one night, and do 

 so. At the same time, they are averse to running risks, and 



