78o NATURAL SCIENCE. 



DEC, 



that the value to students of migration of tliis outpost cannot be 

 reckoned merely by comparative lists of rare wanderers which have 

 turned up on migration there and in the British Islands, but rather by 

 the fact that the red sandstone rock — 28 miles from the nearest coast 

 of Denmark — is directly in the line of the principal bird highway 

 between the north and south of Europe ; while in no other place in the 

 world have continuous notes been taken for fifty years, in connection 

 with bird passage, and these by one of the oldest and most painstaking 

 workers in Europe, one to whom the author of this book is indebted 

 for some of his most interesting facts. 



We think Mr. Dixon greatly overestimates the " Perils of 

 Migration " to birds. These he divides under the heads of " Fatigue," 

 " Natural Enemies," " Blunders and Fatalities on the Way." 

 The death-rate from the three causes he puts as high as 500 to 600 

 for every thousand, or more than one-half, and of these he thinks by 

 far the greater number succumb by sea. During forty years of 

 observation on the East Coast of England we recollect only two 

 instances in which we have found birds washed up in any numbers, 

 and these were rooks, starlings, and redwings. It is true that 

 occasionally, in fogs, snowstorms, and thick weather, as many as 

 1,000 to 1,200 birds are recorded as killed against the lanterns of 

 lighthouses or lightships ; these " big bird nights " are, however, the 

 exception and not the rule, and the loss is small when compared with 

 the multitudes on actual passage. The number of migratory birds 

 which come within the influence of sea-lights is as a drop in the 

 ocean in the great tide sweeping southward over Europe, Asia, and 

 North America, and scarcely worthy of serious consideration. 

 Probably falcons, hawks, owls, and greycrows are no greater causes 

 of destruction to small migrants on passage than at any other period 

 of their existence. 



When on the subject of lighthouses, Mr. Dixon remarks that 

 " The brilhant lamps of the lighthouses are too often the only visible 

 places for which to steer — an inherent knowledge teaches them that 

 light leads to safety." If the author's supposition be correct, then it 

 must have been a bad time for the birds before lights were thought of. 

 Artificial lights are of no use in directing or pointing out the route to 

 be followed, as these beacons must be all much alike to passing flocks. 



As an illustration of the rapidity of flight of some species during 

 the spring migration, Mr. Dixon cites the Dotterel {Eudvomias 

 iiioyinellus), estimating its progress from point to point — that is from 

 North Africa to the Arctic Circle in a single flight between sunset 

 and sunrise — at 200 miles an hour.<^ We doubt very much if normal 

 flight on migration exceeds 50 miles an hour, and very frequently not 



''• When Mr. Dixon says this bird is scarcely ever seen in intermediate places 

 in the spring migration, he appears entirely to have overlooked the fact that it is by 

 no means an uncommon visitor in certain localities on thfe East Coast of England, 

 frequently lingering some time before resuming its journey. 



