13 
the fall migration the younger birds lead,* in the spring they loiter be- 
hind, and it is the old birds, those in whom we may suppose the love 
of home and the desire for procreation are strongest, which press for- 
ward so eagerly. Moreover, of these old birds, those which arrive first 
at a given place, as a rule, are birds which lived there the previous 
summer and which will remain there to breed.{ Thus the vanguard is 
constantly arresting itself, and the forward movement must await the 
arrival of the next corps, which may be near at hand or far in the rear. 
The movement of migration, then, is made up of a series of constant 
overlappings, and the real speed is evidently much greater than the 
apparent. Of this real speed of transit we can take no account, and our 
calculated rates, therefore, are of value only in so far as they show the 
relative speed of migration of the different species. In the accompany- 
ing report the speed of migration is calculated in the following manner: 
The most southern reliable record is selected for comparison with the 
most northern record of the same character; the distance in miles be- 
tween these two stations is divided by the number of days elapsing from 
the time the species made its appearance at the southern station to the 
date at which it was seen by the northern observer. The result gives 
the average daily rate of migration in miles for the species. For exam- 
ple: The Baltimore Oriole was seen at Rodney, Miss, (lat. 31° 52’), April 
7. It was not seen at Oak Point, Manitoba (lat. 50° 30’), until May 25. 
It was therefore 48 days in passing over the 1,298 miles between the 
two stations, which gives an average speed of 27 milesa day. This 
subject will be treated as thoroughly as possible, since it has received 
little or no attention heretofore; indeed, there were no datain existence 
for its study until the notes were collected on which the present report 
is based. 
The first records published in this country relating directly to the 
speed at which birds travel appeared in the Ornithologist and Odlogist 
for January, 1884 (pp. land 2). These notes were based on the records 
of six species in the spring of 1883; and though the notes for 1884 are 
many fold more numerous they do not give grounds for a change in 
the general rate of speed set forth in that article. It must be kept 
constantly in mind, however, that no complete and scientific study of 
the subject is as yet possible, and that the present records are given 
merely because they are the best now obtainable, and because they 
may furnish some material for the use of the future student. 
The records of fifty-eight species for the spring of 1883 give an 
average speed of 23 miles a day for an average distance of 420 miles, 
[* The opinion here expressed by Professor Cooke, namely, that in fall young birds 
migrate before their parents, has been long accepted in Europe, but is contrary to 
the experience of most leading American ornithologists and to the evidence collected 
by the Committee on Migration of the American Ornithoiggists’ Union, as will appear 
in a future publication of the Division. See, also, Mr. Brewster’s recent essay on the 
subject, in the Memoirs of the Nuttall Ornithological Club.—C. H. M.] 
{tThis statement needs much qualification.—C. H. M.] 
