lURDS IN THE FIELD AND GARDEN 187 
has indeed proved that it is tliose very varieties whose miscliief 
is most apparent that do a considerable amount of good as 
a set-off to their depredations. Whether in every case the 
good work accomplished by them is in excess of the harm they 
do, or the reverse, cannot be determined, except by the most 
careful consideration, which must extend over a lengthy period, 
and not be hastily determined upon data furnished at any one 
particular season. And we must further bear in mind the fact 
that the evil that birds do is always the more readily apparent 
to the eye than the good. The farmer, for instance, who notices 
the rooks at work upon his stack, tearing off the thatch to get 
at the corn beneath, has at once primd facie evidence of the ill- 
doing of the rook. But with what amount of certainty can 
he gauge the number of harmful slugs and grubs, or the myriads 
of wireworms, which those selfsame rooks, who are to-day devour- 
ing his corn, have accounted for during the past twelve months ? 
How, again, can the ortlinary gardener, even if he were willing 
to consider the matter, which is indeed seldom, calculate the 
number of snails and other noxious insects destroyed b\' black- 
bird or thrush during the year, in exchange for the strawberries 
and currants of which these birds take toll in the summer ? 
.\nd we have yet another point to consider before we write 
down as useless and inimical to man’s interests those birds 
which admittedly do a certain amount of harm. Any observant 
person, whose studies have been carried out in a careful manner, 
and not onl}' in a superficial way, will be able to testify to the 
fact that in many cases it is the individual of a particular 
species, and not the whole tribe, that is the aggressor. One 
could cite numerous instances, but on the present occasion it 
will suffice to mention one only to illustrate the truth of this 
statement. It is a well-known fact that rooks (to take again 
for our purpose that familiar and much-abused bird) will on 
occasion develop a remarkable liking for the eggs of game and 
poultry, and even the newly hatched young of both. Yet it 
is an absolute fact that in such cases, although the rookery 
may be at no. great distance, the havoc is all wrought by a few 
individuals, who have acquired a vicious taste quite apart from 
that of their tribe. And it has been proved that once these 
individuals have been captured or destroyed the mischief 
ceases as suddenly as it began. Cases of this kind frequently 
come under the observation of poultry-keepers and game- 
preser\^ers, y*et it would be unfair in the face of such evidence 
to condemn the whole tribe of rooks as being generally harmful 
to their interests. As well might one condemn the whole human 
race as murderers and cannibals, because a remote African tribe 
with a propensity for a diet of human flesh has captured a 
missionary and dined off his unfortunate body. 
For the purposes of the matter under discussion birds may 
