the look out, so that the whole level country is thus
under constant supervision, and when a bird is seen to
descend or to be making off, that act serves as notice of
probable quarry for miles around, like the early signal
of the beacon-fire flashed from hill to hill. The usual
sailing motion of the hovering bird is at once changed
for a direct route, and its flight then, as far as I observed,
was always four or five strong flaps of the huge
wings, succeeded by a short straight motionless forward
movement caused by the impetus thus obtained, to be
followed by another four or five flaps as soon as the
former motive power was exhausted. Usually shy,
when gorged with food their habits are quite modified
and they are easily approached. I once came across
more than a hundred settled about two dead oxen.
On each carcass were ten or twelve vultures at
work, whilst the others in listless and gorged apathy
rested around. The naturalist who has skinned a full-
grown and full-fed vulture will not easily forget the
operation. Now that the vast herds of game which
once roamed over the veld are practically exterminated,
the vulture becomes more dependent for its provender
on the deceased domestic oxen bred by man, and the
body of an ox is much preferred to that of a horse.
Their food around Pretoria may become scarcer, as a
movement was on foot to form a commercial company
for gathering up these carcasses to boil down for soap.
About the town gardens a bird almost as common as
the sparrow in England is the Cape Wagtail (Motacilla
capensis), but which by its tameness and partiality for
the habitations of man reminded me of our robin, and,
like that bird, is as little molested, save by boys, the
natural enemies of all birds. Many entomologists have
recorded the fact that they have never seen a butterfly
attacked by a bird ; but I not only obtained an Arctiid
moth (Binna madagascariensis), which I surprised one
of these birds in the act of killing, but also saw another
actually pursuing a butterfly belonging to the genus
Acrcea, which is generally exempt from these attacks.
After an interval of some fifteen years Pretoria was
visited early in the month of May by a prodigious swarm
of locusts (Pachytylus migratoroides) *. Travellers from
the coast had passed through these devastating insect
hordes, which apparently were working their way up
from the Cape Colony. On the morning of May 11th
our attention had been directed to myriads of locusts
flying near the hills, and some few stragglers were
LoCTTST-SWABM IN PB ETOBIA.
found in the town; but shortly after noon the air was
darkened, as swarms only to be computed by billions
came with a rushing sound over our heads and across
* The traveller Mohr met with similar swarms of probably the same locust
on the banks'of the Yaal River in 1869 (‘To the Victoria Falls of the
Zambesi,’ p. 94).