172 Wud Life in a Southern County. 
avenue in question might become stocked with 
rooks, 
One reason, I fancy, why nests begun in such 
distant trees are so often deserted before completion 
is that a solitary nest exposes both the building 
birds and their prospective offspring to grave danger 
from hawks. No hawk will attempt to approach a 
rookery—the rooks would attack him en masse and 
easily put him to flight. Chickens are safer under or 
near a rookery from this cause: a hawk approaching 
them would alarm the rooks and be beaten away. 
The comparative safety afforded by numbers is per- 
haps a reason why many species of birds are grega- 
tious. The apparently defenceless martins and swal- 
lows in this way dwell in some amount of security. 
If a hawk comes near the sand quarry (or the house— 
in the case of swallows) they all join together and 
pursue him, twittering angrily, and as a matter of 
fact generally succeed in sending him about his 
business. Even those birds which do not build in 
close contiguity no sooner find that a hawk is near 
than they rise simultaneously and follow and annoy 
him: so much so that he will sometimes actually 
drop the prey he has captured. It is astonishing with 
what temerity small birds, emboldened by numbers— 
chaffinches, finches generally, sparrows, swallows, and 
so on—will attack a hawk. 
The ‘quar-martins ’ that came to the orchard wall 
—emigrating from the quarry, and wandering about in 
