A History 
of Birds. 
(454) 
THE BIRD WORLD. 
well illustrated by such birds as the Swift and 
Swallow, while, as is well known, birds with 
short, rounded wings are poor fliers. As to the 
speed at which birds fly. A great many extra¬ 
ordinary statements have been made on this sub¬ 
ject. The American Golden Plover, for instance, 
has been said to cover no less than 1,700 miles 
in a single night while on migration ! Never¬ 
theless, there is no doubt that a high speed is 
maintained by many species. The Swallow, for 
instance, can probably on occasion attain and 
keep up a rate of about 100 miles per hour, 
while the homing Pigeons, according to the 
records of one of the Pigeon-flying clubs, may 
attain a rate of over eighty miles per hour. Fifty 
miles has certainly been attained, but between 
thirty and forty appears to be the average over 
long courses. 
tahrcGlatfy 
row 
The Powers 
the Tail. 
of 
trmariiEs 
Fig. 3.—Wing of a bird to show the covert feathers and their overlap. The major 
coverts have a distal overlap. What is meant by a ‘ provisional ’ overlap can be 
seen in the medium and minor rows. What is known as the “ intercalary ” row 
occurs in nearly all wings which have no 5in. secondary. 
The part played 
by the tail dur¬ 
ing flight is com¬ 
monly believed to 
be that of steer¬ 
ing. As a matter 
of fact, the tail 
is but an indif- 
f e r e n t steering 
agent, but is 
used with great 
effect in mak¬ 
ing sudden turns, 
balancing, and 
checking flight 
when alighting 
or taking a new direction. Turning move¬ 
ments are effected rather by flinging the weight 
of the body over in the desired direction, 
much as a cyclist in turning a corner bends 
his body over from the vertical. When, in 
flight, this alteration in the poise of the body is 
made, one wing is thrown up and the other 
down, and as a consequence the body, following 
along the line of least resistance, the course is 
altered. It is chiefly in sudden turns and twists 
during flight, and in alighting, that the tail is 
used, and during this latter movement the short 
quills of the bastard wing are also used. These 
tiny feathers are further called into play in check¬ 
ing flight as when a sudden stoppage is neces¬ 
sary. The marvellous soaring powers which 
some birds, such as the Eagles, Kites, 
Adjutant Storks, and Pelicans possess in such 
high degree have exercised the minds of some of 
TBwrginal 
covjrtf 
the acutest of bird students, yet even now we are 
almost entirely in the dark as to how this form 
of flight is sustained. According to some, the 
bird mounts by taking advantage of up cur¬ 
rents of air, while, according to others, it utilises 
horizontal currents of varying degrees of 
velocity. Probably both are right. Soaring 
differs from the normal flight in that the birds 
mount in spiral circles on fully-extended and 
motionless wings. The problem of flight is one 
that has come much to the fore of late by the 
impetus which new inventions have given to the 
development of flying machines. But, fascinating 
as the matter is, only those who are tolerably 
familiar with physics and mathematics can 
really acquire a thorough grasp of all the factors 
that must be reckoned with to make it really 
intelligible, and 
these are few. 
Nevertheless, t o 
most of us the 
consciousness that 
flight presents 
p r o b lems which 
we cannot solve is 
a trial lightly 
borne. We enjoy, 
perhaps, all the 
more the rare de¬ 
light of a flock of 
Starlings at even¬ 
tide, and marvel 
the more at their 
wonderful evolu¬ 
tions ; we enjoy no 
less to watch 
the flocks of 
Dunlin on the 
mud-flats in autumn as they wheel about, now 
looking like a small snowstorm and now 
well-nigh invisible as they turn towards 
us, first the dazzling white of the under¬ 
wing and breast and then the dusky 
upper parts. In flight of this kind, furthermore, 
something more than mathematics has to be 
taken into consideration; the marvellous co¬ 
ordination of movement pervading huge num¬ 
bers such as are often seen in the Starling flights 
seems to defy analysis. Who gives the word of 
command, and by what magic is it passed, so 
that the host changes form with the exactness 
and suddenness of a kaleidoscope? Is this 
amazing unison reached only after laborious re¬ 
hearsals, or is it instinctive? What purpose 
does it serve? These are questions which appear 
well-nigh insoluble, yet, perhaps, on this account 
they become the more alluring. 
>1/ covert* 
X^snajor 
<pvrrF 
Cubital^ 
(To be continued .) 
