these,, and probably many others equally injurious to vegetation,
are searched for and devoured with avidity* forming a
very large proportion of the food' of this most numerous species.
Early in the morning Rooks visit meadow land while
the grass is yet wet with dew, to—break their fast on worms
and slugs, which the moisture of that period induces to crawl
forth. Later .in the day, they may*fife seeii either searching
newly ploughed ground for the various insects there exposed,
or again visiting pastures for other purposes. There they
are accused of destroying the grass by pulling it up : by the.
roots; “ but it has been stated, and I believe truly, that
this is an error arising out of the following circumstance—
In searching for grubs which' are concealed in the earth, and
supported by eating the roots of the grass, the Rook pulls at
the blade of grass with its . bill, and when the grass.comes-up
readily, the bird knows that there are under it insects which
have destroyed its roots,' and. in this way.detects them; but if
the blade of grass is. firm, the Rook goes to another part of-the
ground. In a field where grubs are very abundant, the Rooks
scatter the grass everywhere,; go as to give the appearance of
having rooted it up, while they have only exposed the depredations
of the insects by which the roots have, been destroyed.”
The author of the Journal of a Naturalist, speaking-jpf the
readiness with which Rooks detect the places where grubs
are sure to be found, says, ‘.‘. I have often observed--them
alight on a pasture of uniform verdure, and exhibiting no
sensible appearance of feathering or decay, and immediately
commence stocking up the ground. Upon investigating the
object of their operations, I have found many heads f f iplam
tains, the little autumnal dandelions', and Other plants, drawn
out of the ground, and scattered about, their roots having
been eaten off by a grub, leaving only a crown of leaves upon
the surface.” I t may readily be supposed that extensive
injury at the root of a plant-cannot; exist long without gome
alteration in. the appearance; of’ the leaves, or other parts,
above ground,. and the;Ro.oks seem to have learned by
experience how.do^seibnt those plants which are the' most
likely to afford th.enj--some recompence for. the trouble they
take in grubbing them up. Mr. Jesse, in his instructive
Gleanings, says,*# A gentleman once showed me a field
which had all the appearance o£ having been scorched* as if
by a burning sun in dry hot weather. -The turf peeled from
tfee , ground as if it had* been -euLwith^a turfing-spade, and
we then discovered that the roots;of the grass had been eaten
away by the larvee of" the cock-chaffer, which were found in
countless numbers at various, depths in the soil. This field
was visited b y a great quantity of Rooks,' thpugh there was
no rookery within many miles of- the neighbourhood,, who
turned up,- and ■ appeared- to ,'devpur .the; grubs with great
satisfaction, Tcg&ojve.their utility on other.occasions,, two
or three quotations from the Magazine of Natural History;
among many others, wil suffice. A flight of locusts visited
Graven^ and-they wbre:tat numerous as‘do .create considerable
alarm among thé farmers of‘thé. district! They-were,f however*'
;So.on relieved* froth their-anxiety, for the Rooks fh^ked
in from all-quarters by thousands, and tens of thousands, and
devoured them so greedily that | theyuwere all destroyed in
a short-time. I t was stated a few years ago, that there; was
such an enormous -quantity of caterpillars upon Skiddaw, that
they devoured all the vegetation on the mountain; and
people were apprehensivefthey wouldfc'attack i®e crops in .the
enclose! lands; but the Rooks, whipfe. sire fond saf high
ground , in summer, having discovered them, in a very short
time put a stop to their ravages.
The attempts occasionally made by man to- interfere with
the balance of powers as arranged and sustained - by Nature
are seldom successful^ “ An extensive experiment appears
to have, been made in some o f f he agricultural districts on the