20 6 
BIRDS OF PASSAGE, 
From the 
slowness of 
migration, it| 
may be per- 
formed by 
feeble birds. 
Vernal course 
«f the swallow, 
This deliberate manner of travelling relieves the theory of 
migration from one of its principal difficulties. For this sup- 
position makes an easy task of a long journey to those birds of 
passage which are not remarkable for agility and power of 
wing ; such as the red-start, the yellow-wren, the nightingale, 
and other species. These wandering birds are not required by 
the theory, to fly with the greatest expedition through 40 or 50 
degrees of latitude, from their winter quarters to their summer 
haunts. On the contrary, one of them has been proved to move 
slowly from one station to another, as the sun advances in his re- 
turn towards the tropic of Cancer. The winter labours of the jack 
snipe, which is remarkable for its inactive habits, confirm the 
foregoing supposition. For this bird quits the northern regions 
early in autumn : and, in spite of its natural feebleness and 
indolence, makes a shift to travel over the greatest part of 
Europe in the cold season. The woodcock also, after leaving 
the same summer retreats, makes a similar journey, and passes 
over into Africa. 
I shall now proceed to give a few points in the vernal course 
* of the chimney swallow ( Hirundo rustica,) which is known to 
travel in the spring from Senegal, in latitude 16° north, to 
Drontheipa, in latitude 64° north. This bird appears in the 
neighbourhood of Senegal on the 6th of October ; and has 
been seen as late as February in the same country. It is said to 
arrive at Athens, in lat. 37° 25". on the 18th of February ; at 
Rome, in lat. 41° 45', on the 22d of the same month ; at Pia- 
cenza, in lat. 45°, March 20th, A. D. 1/38 ; at Tzaritzin, in 
lat. 48° 30% April 4th ; in the late spring of 17§)3, at Catsfield, 
lat. 51°, April 14th, from a mean of twenty observations; at 
Stratton, lat. 52° 45', April 8th, from a mean of twenty obser- 
vations ; at Kendal, lat. 54 20', April 17th, from a mean of 
twenty- three observations; at Upsal, lat. 59 0 30*, May gth, 
from one observation. 
This route of the swallow towards the arctic circle, shews 
that the bird does not rely on its agility, and loiter in fhe torrid 
zone longer than is necessary. On the contrary, it travels 
slowly from climate to climate, until the sun is in 17 or 18 de- 
grees of northern declination, and spring has made considerable 
advances in the ungenial climate of Sweden. One anomaly 
occurs in the vernal progress of the swallow, which deserves the 
attention 
