10
THE PRESIDENTIAL ADDRESS.
Edwards' pamphlet, already noticed, gave a most philosophic
account of normal bird migration, and except in the details of geo-
graphical distribution it very fairly represents our present knowledge
of the subject. His explanation was that the summer birds of pass-
age remove at the commencement of our winter to warmer climates,
where they meet with a supply of food and a temperature of air
adapted to their constitutions. He also says, "It is no less true
than remarkable that Swallows annually return to their respective
haunts, and claim the same nests which they occupied the preced-
ing season" (l.c, p. 29) ; abundant recent evidence of this could be
produced both where marked birds have returned and where pecu-
liarly placed situations have been re-occupied, and many of us must
remember instances where we have found similar nests in similar
sites year after year ; these, presumably, are not always built by
entire strangers. Edwards relates an experiment; he says, "Fly-
catchers I have known to build eight, nine, and even ten years
successively, in a certain crevice of an old wall, not far from my
dwelling. Apprehensive that it was the same bird which annu-
ally and invariably visited the spot, curiosity prompted me to try an
experiment which put the matter out of doubt. When an opportunity
offered, I took the female, cut off the extremity of the upper mandible
of the bill, and with a knife made several perspicuous marks on its
claws : this done, I set her at liberty. The succeeding spring the
same bird returned, with the distinguishing marks I had given it,
which was at once satisfactory. Perhaps some will say it is impos-
sible the bird should survive after it was deprived of the point of its
bill ; they will, however, please to observe that what was cut off was
so very inconsiderable, that the loss of it could hardly be perceptible
to the bird ; it could not, therefore, be any way detrimental to its
feeding" (l.c, p. 30, note).
Search for food alone could not be the guiding principle here, un-
erringly directing the African traveller to the same spot year after year.
Ray might well ask, "But how come they to be directed to the same
place yearly, though sometimes but a little island, as the Soland
Goose to the Basse of Edinburgh Frith, which they could not pos-
sibly see, and so it could have no influence on them that way?"™
Professor Newton gives two remarkable instances of birds persistently
nesting in the same spot.21 And surely it cannot be said that the
20 "Wisdom of God in Creation," 7th ed., p. 129.
21 The Peregrine Falcon on Avasaxa (Finland) from 1736 to 1855, and the case of a large
earthenware bottle in an apple tree at Oxbridge, near Stockton-on-Tees, occupied by the Blue