152 



THE NIDIOLOGIST 



ing from a trip one dark evening, I came upon 

 an Eagle perched on a wire fence, and suc- 

 ceeded in putting my hand within a foot of its 

 talons when it flew over the fence to the ground 

 about twenty feet away. 



With what information I have gathered in re- 

 gard to nests of the Golden Eagle I am of the 

 opinion that Monterey County contains as many 

 as does either Santa Clara or San Benito. 



Westfield, Ind. L. W. Brokaw. 



Migration. 



IT is only recently, comparatively speaking, 

 that distribution has been recognized as an 

 important factor in biology. Darwin and 

 Wallace have taught us that species are highly 

 differentiated under the influences of surround- 

 ings, and have shown the significance of the 

 remarkable peculiarities found among insular 

 or isolated forms, and the importance of accu- 

 rate data regarding location and surround- 

 ings has been recognized. 



Among many of the earlier naturalists we 

 find a carelessness which now appears positive- 

 ly criminal. Forster, the scientist who accom- 

 panied Captain Cook, would preserve a speci- 

 men of a rare bird with no memoranda except, 

 perhaps, the remark that it was found on one 

 of the islands of the South Sea. Even so great 

 a naturalist as Le Vaillant described many of 

 his South African birds from memory. The 

 early navigators, after circumnavigating the 

 globe and collecting in many lands, would trust 

 to memory for data, and sometimes attribute 

 to one continent specimens which we now 

 know must have been collected on another. 



The damage done by some of these inaccura- 

 cies is irreparable. There were species known 

 to civilized men 150 or 200 years ago, but now 

 extinct, concerning which we can arrive at no 

 imjjortant conclusion, because, although speci- 

 mens of them may have been preserved, noth- 

 ing accurate and reliable has been recorded 

 concerning them. Specimens have been too 

 often collected as mere curiosities instead of 

 scientific material. 



All this is now changed, at least among in- 

 telligent students, and the field naturalist 

 and the systematist supplement each other's 

 labors, and no fact observed is considered too 

 trivial to be recorded. 



The collection of really valuable material was 

 begun late, but it has progressed rapidly, and 

 from the mass of accumulated facts many of 

 the circumstances once deemed inscrutable 

 mysteries are explained, or at least are begin- 

 ning to be understood. 



One of the most abstruse of these problems 



is that of bird migration, a phenomeron which 

 furnished a theme for the Greek and Hebrew 

 poets three thousand years ago. Whence the 

 migrating birds came and whither they went, 

 once merely themes of conjecture, at last be- 

 came subjects of investigation. A traveler 

 from a tem])erate region, when spending a win- 

 ter in any ])art of the tropics, might care very 

 little for science, but still he could not help but 

 notice the number of familiar forms to be 

 found wintering there, and when in the north 

 their summer quarters often force themselves 

 on his notice. 



Facts thus accumulated have so growrw in 

 volume that, with the exception of the Curlew 

 Sandjiiper, Tringa sitbarquata, we can now 

 point with certainty to the summer and winter 

 abodes of all the birds of Euroj)eand America, 

 though the limits of their ranges are not defi- 

 nitely known. 



The details of these migrations are still im- 

 perfectly understood in spite of the extended 

 investigations of Professor Spencer F. Baird, 

 W. W. Cooke, and a host of others. 



Some species make their long journey ap- 

 parently without a halt. Dr. Jerdon says that 

 the Spine-tailed Swift {AcauthyUis candacutus) 

 leaves Ceylon in the morning and reaches the 

 Himalayas, distant 1.200 miles, before sunset. 

 The Cyaneciila suecica, Blue-throat, is abundant 

 in Sweden in summer, and in Egypt and Syria 

 in winter, but it is said never to be found in 

 central or southern Europe, crossing the con- 

 tinent, as it would appear, at a single flight. 

 A still longer single flight is that of the Afri- 

 can Darter which rears its young every spring 

 in northern Syria and winters in southern 

 Africa, but which has never been seen in Af- 

 rica north of the great lakes. Equally strik- 

 ing instances of long flights on our own conti- 

 nent could be mentioned. 



Other species are more leisurely in their 

 travels, and have many old haunts and favored 

 spots which they visit annually or semiannually. 



There are differences quite as marked in 

 the elevation at which their migratory flights 

 are carried on. Some species appear to travel 

 near the ground and direct their routes by the 

 course of streams and the position of moun- 

 tain ranges. Others fly at so great an altitude 

 that the topographic features of the region 

 traversed can have no influence on their direc- 

 tion. Observers from the tops of mountains 

 five and six thousand feet in height often see 

 common birds pass in their migrations at a 

 height which makes them indistinguishable ex- 

 cei)t by the aid of field glasses. 



Besides their ordinary migrations with the 

 seasons birds often display a tendency to erratic 

 migrations from east to west or from west to 



