5 
set in as would prove fatal to their existence, either on account of the 
lowering of the temperature or the cessation of suitable food. By the 
end of September the great mass have departed, and only a scanty 
remnant are to be met with. With this same ebb, the autumnal 
months bring to our sight again strings of grallatorial and nata- 
torial birds, urged by similar causes from the northern regions 
back towards the south in search of that food and aquatic life which 
the icy hand of winter had already begun to grudge them and their 
progeny in their summer location. ‘To follow the sun appears 
to be the course of true migration; but the promptings of instinct 
which lead the Swallow and many other species to quit our shores, 
after a brief sojourn, for Africa, or those which lead the Fieldfare 
and the Redwing to quit the Norwegian ‘fjelds’ for our cultivated 
lands, must surely be connected in some way with, 1f they have not 
for their sole object, the provision of food and climate suitable to the 
species. The Rey. H. b. Tristram remarks that ‘‘ those species which 
have the most extended northerly have also the most southerly range, 
and that those which resort to the highest latitudes for nidification 
also pass further than others to the southward in winter. Thus the 
migratory Fieldfare and Redwing, visiting regions north of the limits 
of the Thrush and Blackbird, on their southern migrations likewise 
leave their more sedentary relatives behind. The Brambling, which 
passes the Chaftinch in Norway, leaves it also in Europe, and crosses 
the Mediterranean every winter to the Barbary states.” (Ibis, 1865, 
await) 
The regularity, however, which occurs in the arrivals of our summer 
visitants is not quite so strictly adhered to in their departures. 
Having accomplished the purpose for which they came, these depart 
again at varying periods, but mostly as soon as the renewal of their 
primaries will admit of their flying across the channel, leaving their 
young to follow instinctively ( when their muscular development has 
been sufficiently matured) the same route by which their parents have 
preceded them. This apparent desertion of the young birds at a 
period when one would imagine the presence of their parents as 
leaders would be absolutely essential, seems to prevail amongst many 
of our migratory species. That the old birds should be able instine- 
tively to wing their way back to whence they came is not half so 
marvellous as that the newly fledged nestling, urged by some mys- 
terious power, should undertake a flight extending over hundreds of 
miles and many variations of climate in search of a temporary home 
it has never scen. This irresistible impulse, which prompts the ne- 
cessity of a migration somewhither, is but too sadly seen in the rest- 
less actions and almost frantic efforts of the caged Turtle Dove, 
Nightingale, or Whitethroat during the period at ‘which, were they 
free, they would be leaving our shore; once let that period be passed, 
their efforts cease, and apparent resignation to their prison ensues. 
“Tt sometimes happens,” says Mr. R. Gray, “ that Swifts, obeying 
their unconquerable instincts, will at the close of a stormy season 
desert their unfledged young, and leave them to perish of hunger, 
Late breeds especially are subject to this unnatural desertion, 
