October, 1931. 
The Queensland Naturalist 
7 
to the close association of the calcic rocks with the Pacific 
Ocean, the term calcic and Pacific are sometimes used 
synonymously. The Atlantic Ocean is characterised much 
more by the presence of alkaline rocks. 
Special consideration was given by the lecturer to’ the 
Hawaiian Volcanic activity, and especially to Kilauea. It 
was pointed out that at the latter place there was a special 
volcano station under the charge of Dr. Jaggar, and from 
it the mechanism of volcanoes was now much better under- 
stood as a result of studies made at this place. 
Submarine volcanic activity was then considered and 
it was shown that the Hawaiian Islands had been built 
up from the sea-floor to a height of 30,000 feet. 
By means of 60 carefully selected lantern slides the 
various features of the volcanoes of the Pacific were illus- 
trated. 
NOTES ON THE ECONOMIC VALUE (OR OTHER- 
WISE) OF SOME OF OUR DIURNAL BIRDS 
OF PREY, INCLUDING CROWS. 
By H. Greensill Barnard. 
(Read before the Queensland Naturalists’ Club, 
1 9th October, 1931.) 
Mv paper to-night will probably call forth adverse 
comment, from some of those present, because I intend to 
deal with the economic value, “or otherwise,” of some of 
our most disliked birds. I refer to hawks and crows. 
Many people, bushmen as w r ell as those in settled 
parts, cannot see any good in either hawks or crows. Yet 
I venture to assert that if the hawks and crows were ex- 
terminated in the Central parts of Australia, it would be 
impossible to raise flocks and herds there. 
After a dry season, when rainfalls and the young grass 
is again covering the ground with a mantle of green, one 
notices, when riding or driving over the country, dark 
brown patches. Some of these patches are small, others of 
large extent. On examination it will be found these 
patches consist of millions of baby grasshoppers, or locusts. 
Though if you called them locusts most bushmen would 
not know what you meant. They are all grasshoppers to 
the man on the land. 
While the grasshoppers confine themselves mostly to 
the grass, swarms of caterpillars appear on the young 
herbage, and it is now that the value of some of our hawks 
and the crows is seen. 
