fowl northward in the spring and Anacreon, in classic lines, wel¬ 
comed the returning swallow five centuries before Christ. 
Schlegel' “ ^“ ! Serious attempts to ascertain the facts of mi¬ 
gration in any detail have been attempted only 
within the last century. . For instance in 1828 Schlegel of Haar¬ 
lem made an analysis of the accounts of travelers in various lands 
upon 130 different journeys. After compiling all references which 
these travelers made to the birds which they saw he concluded 
from these heterogeneous statistics that, for any given locality, 
birds might be divided into three groups; first, residents, who re¬ 
main all the year in one locality; second, erratic wanderers, who' 
appear irregularly, and third, migrants, who pass through the lo¬ 
cality at regular times. Since Schlegel’s time there has followed 
many years of faunistic work by various observers who have cata¬ 
logued the birds known to occur in different localities. This ex¬ 
tremely useful kind of work is still being done in both hemispheres, 
since, until the general distribution of birds is more accurately 
known mere speculation upon their movements is productive of 
few results. 
von Middendorf 1855 von Middendorf of St. Petersburg 
combined all the faunistic data then available in 
an attempt to find out the manner of bird movements by means 
of what he termed isopeptic lines. The isopeptic lines were arbi¬ 
trarily formed by connecting the points of first arrival of certain 
species over as large an area as possible for any one date. By 
constructing a series of such isopeptic lines upon the map of Rus¬ 
sia for succeeding dates he obtained a graphic representation of 
the kind of advance made during migration, throughout that re¬ 
gion, drawing therefrom the general conclusion that birds move 
forward during migration in a broad front. Furthermore, the di¬ 
rection of the main European migration routes he determined the¬ 
oretically by extending lines at right angles to the isopeptic lines. 
Sundevall and It soon came to be seen, however, that only 
general results could be hoped for so long as 
particular instances were not known. The first attempt to obtain 
detailed data concerning the movements of any single> species of 
birds was the outcome of a correspondence about the migration 
of storks begun during 1862 between Sundevall in Sweden and 
Peters in Berlin. These two naturalists called upon their col¬ 
leagues to aid them in making observations at various localities. 
Thus in a short time a large amount of data was collected con¬ 
cerning the migratory movements of storks, a species particularly 
favorable for study by reason of their being so conspicuous and 
