Charles Darwin.

The Voyage of the Beagle online

. (page 10 of 51)
Online LibraryCharles DarwinThe Voyage of the Beagle → online text (page 10 of 51)
Font size
QR-code for this ebook

animals can find support in a country producing so little food. The
larger quadrupeds no doubt roam over wide tracts in search of it;
and their food chiefly consists of underwood, which probably
contains much nutriment in a small bulk. Dr. Smith also informs me
that the vegetation has a rapid growth; no sooner is a part
consumed, than its place is supplied by a fresh stock. There can be
no doubt, however, that our ideas respecting the apparent amount of
food necessary for the support of large quadrupeds are much
exaggerated: it should have been remembered that the camel, an
animal of no mean bulk, has always been considered as the emblem of
the desert.

The belief that where large quadrupeds exist, the vegetation must
necessarily be luxuriant, is the more remarkable, because the
converse is far from true. Mr. Burchell observed to me that when
entering Brazil, nothing struck him more forcibly than the
splendour of the South American vegetation contrasted with that of
South Africa, together with the absence of all large quadrupeds. In
his "Travels," he has suggested that the comparison of the
respective weights (if there were sufficient data) of an equal
number of the largest herbivorous quadrupeds of each country would
be extremely curious. (5/6. "Travels in the Interior of South
Africa" volume 2 page 207.) If we take on the one side, the
elephant, hippopotamus, giraffe, bos caffer, elan, certainly three,
and probably five species of rhinoceros; and on the American side,
two tapirs, the guanaco, three deer, the vicuna, peccari, capybara
(after which we must choose from the monkeys to complete the
number), and then place these two groups alongside each other, it
is not easy to conceive ranks more disproportionate in size. (5/7.
The elephant which was killed at Exeter Change was estimated (being
partly weighed) at five tons and a half. The elephant actress, as I
was informed, weighed one ton less; so that we may take five as the
average of a full-grown elephant. I was told at the Surry Gardens,
that a hippopotamus which was sent to England cut up into pieces
was estimated at three tons and a half; we will call it three. From
these premises we may give three tons and a half to each of the
five rhinoceroses; perhaps a ton to the giraffe, and half to the
bos caffer as well as to the elan (a large ox weighs from 1200 to
1500 pounds). This will give an average (from the above estimates)
of 2.7 of a ton for the ten largest herbivorous animals of Southern
Africa. In South America, allowing 1200 pounds for the two tapirs
together, 550 for the guanaco and vicuna, 500 for three deer, 300
for the capybara, peccari, and a monkey, we shall have an average
of 250 pounds, which I believe is overstating the result. The ratio
will therefore be as 6048 to 250, or 24 to 1, for the ten largest
animals from the two continents.) After the above facts, we are
compelled to conclude, against anterior probability, that among the
mammalia there exists no close relation between the BULK of the
species and the QUANTITY of the vegetation in the countries which
they inhabit. (5/8. If we suppose the case of the discovery of a
skeleton of a Greenland whale in a fossil state, not a single
cetaceous animal being known to exist, what naturalist would have
ventured conjecture on the possibility of a carcass so gigantic
being supported on the minute crustacea and mollusca living in the
frozen seas of the extreme North?)

With regard to the number of large quadrupeds, there certainly
exists no quarter of the globe which will bear comparison with
Southern Africa. After the different statements which have been
given, the extremely desert character of that region will not be
disputed. In the European division of the world, we must look back
to the tertiary epochs, to find a condition of things among the
mammalia, resembling that now existing at the Cape of Good Hope.
Those tertiary epochs, which we are apt to consider as abounding to
an astonishing degree with large animals, because we find the
remains of many ages accumulated at certain spots, could hardly
boast of more large quadrupeds than Southern Africa does at
present. If we speculate on the condition of the vegetation during
those epochs, we are at least bound so far to consider existing
analogies, as not to urge as absolutely necessary a luxuriant
vegetation, when we see a state of things so totally different at
the Cape of Good Hope.

We know that the extreme regions of North America many degrees
beyond the limit where the ground at the depth of a few feet
remains perpetually congealed, are covered by forests of large and
tall trees. (5/9. See "Zoological Remarks to Captain Back's
Expedition" by Dr. Richardson. He says, "The subsoil north of
latitude 56 degrees is perpetually frozen, the thaw on the coast
not penetrating above three feet, and at Bear Lake, in latitude 64
degrees, not more than twenty inches. The frozen substratum does
not of itself destroy vegetation, for forests flourish on the
surface, at a distance from the coast.") In a like manner, in
Siberia, we have woods of birch, fir, aspen, and larch, growing in
a latitude (64 degrees) where the mean temperature of the air falls
below the freezing point, and where the earth is so completely
frozen, that the carcass of an animal embedded in it is perfectly
preserved. (5/10. See Humboldt "Fragmens Asiatiques" page 386:
Barton's "Geography of Plants"; and Malte Brun. In the latter work
it is said that the limit of the growth of trees in Siberia may be
drawn under the parallel of 70 degrees.) With these facts we must
grant, as far as QUANTITY ALONE of vegetation is concerned, that
the great quadrupeds of the later tertiary epochs might, in most
parts of Northern Europe and Asia, have lived on the spots where
their remains are now found. I do not here speak of the KIND of
vegetation necessary for their support; because, as there is
evidence of physical changes, and as the animals have become
extinct, so may we suppose that the species of plants have likewise
been changed.

These remarks, I may be permitted to add, directly bear on the case
of the Siberian animals preserved in ice. The firm conviction of
the necessity of a vegetation possessing a character of tropical
luxuriance, to support such large animals, and the impossibility of
reconciling this with the proximity of perpetual congelation, was
one chief cause of the several theories of sudden revolutions of
climate, and of overwhelming catastrophes, which were invented to
account for their entombment. I am far from supposing that the
climate has not changed since the period when those animals lived,
which now lie buried in the ice. At present I only wish to show,
that as far as QUANTITY of food ALONE is concerned, the ancient
rhinoceroses might have roamed over the STEPPES of central Siberia
(the northern parts probably being under water) even in their
present condition, as well as the living rhinoceroses and elephants
over the KARROS of Southern Africa.

I will now give an account of the habits of some of the more
interesting birds which are common on the wild plains of Northern
Patagonia: and first for the largest, or South American ostrich.
The ordinary habits of the ostrich are familiar to every one. They
live on vegetable matter, such as roots and grass; but at Bahia
Blanca I have repeatedly seen three or four come down at low water
to the extensive mudbanks which are then dry, for the sake, as the
Gauchos say, of feeding on small fish. Although the ostrich in its
habits is so shy, wary, and solitary, and although so fleet in its
pace, it is caught without much difficulty by the Indian or Gaucho
armed with the bolas. When several horsemen appear in a semicircle,
it becomes confounded, and does not know which way to escape. They
generally prefer running against the wind; yet at the first start
they expand their wings, and like a vessel make all sail. On one
fine hot day I saw several ostriches enter a bed of tall rushes,
where they squatted concealed, till quite closely approached. It is
not generally known that ostriches readily take to the water. Mr.
King informs me that at the Bay of San Blas, and at Port Valdes in
Patagonia, he saw these birds swimming several times from island to
island. They ran into the water both when driven down to a point,
and likewise of their own accord when not frightened: the distance
crossed was about two hundred yards. When swimming, very little of
their bodies appear above water; their necks are extended a little
forward, and their progress is slow. On two occasions I saw some
ostriches swimming across the Santa Cruz river, where its course
was about four hundred yards wide, and the stream rapid. Captain
Sturt, when descending the Murrumbidgee, in Australia, saw two emus
in the act of swimming. (5/11. Sturt's Travels, volume 2 page 74.)

The inhabitants of the country readily distinguish, even at a
distance, the cock bird from the hen. The former is larger and
darker-coloured, and has a bigger head. (5/12. A Gucho assured me
that he had once seen a snow-white or Albino variety, and that it
was a most beautiful bird.) The ostrich, I believe the cock, emits
a singular, deep-toned, hissing note: when first I heard it,
standing in the midst of some sand-hillocks, I thought it was made
by some wild beast, for it is a sound that one cannot tell whence
it comes, or from how far distant. When we were at Bahia Blanca in
the months of September and October, the eggs, in extraordinary
numbers, were found all over the country. They lie either scattered
and single, in which case they are never hatched, and are called by
the Spaniards huachos; or they are collected together into a
shallow excavation, which forms the nest. Out of the four nests
which I saw, three contained twenty-two eggs each, and the fourth
twenty-seven. In one day's hunting on horseback sixty-four eggs
were found; forty-four of these were in two nests, and the
remaining twenty, scattered huachos. The Gauchos unanimously
affirm, and there is no reason to doubt their statement, that the
male bird alone hatches the eggs, and for some time afterwards
accompanies the young. The cock when on the nest lies very close; I
have myself almost ridden over one. It is asserted that at such
times they are occasionally fierce, and even dangerous, and that
they have been known to attack a man on horseback, trying to kick
and leap on him. My informer pointed out to me an old man, whom he
had seen much terrified by one chasing him. I observe in Burchell's
"Travels in South Africa" that he remarks, "Having killed a male
ostrich, and the feathers being dirty, it was said by the
Hottentots to be a nest bird." I understand that the male emu in
the Zoological Gardens takes charge of the nest: this habit,
therefore, is common to the family.

The Gauchos unanimously affirm that several females lay in one
nest. I have been positively told that four or five hen birds have
been watched to go in the middle of the day, one after the other,
to the same nest. I may add, also, that it is believed in Africa
that two or more females lay in one nest. (5/13. Burchell's
"Travels" volume 1 page 280.) Although this habit at first appears
very strange, I think the cause may be explained in a simple
manner. The number of eggs in the nest varies from twenty to forty,
and even to fifty; and according to Azara, sometimes to seventy or
eighty. Now although it is most probable, from the number of eggs
found in one district being so extraordinarily great in proportion
to the parent birds, and likewise from the state of the ovarium of
the hen, that she may in the course of the season lay a large
number, yet the time required must be very long. Azara states that
a female in a state of domestication laid seventeen eggs, each at
the interval of three days one from another. (5/14. Azara volume 4
page 173.) If the hen was obliged to hatch her own eggs, before the
last was laid the first probably would be addled; but if each laid
a few eggs at successive periods, in different nests, and several
hens, as is stated to be the case, combined together, then the eggs
in one collection would be nearly of the same age. If the number of
eggs in one of these nests is, as I believe, not greater on an
average than the number laid by one female in the season, then
there must be as many nests as females, and each cock bird will
have its fair share of the labour of incubation; and that during a
period when the females probably could not sit, from not having
finished laying. (5/15. Lichtenstein, however, asserts "Travels"
volume 2 page 25, that the hens begin sitting when they have laid
ten or twelve eggs; and that they continue laying, I presume in
another nest. This appears to me very improbable. He asserts that
four or five hens associate for incubation with one cock, who sits
only at night.) I have before mentioned the great numbers of
huachos, or deserted eggs; so that in one day's hunting twenty were
found in this state. It appears odd that so many should be wasted.
Does it not arise from the difficulty of several females
associating together, and finding a male ready to undertake the
office of incubation? It is evident that there must at first be
some degree of association between at least two females; otherwise
the eggs would remain scattered over the wide plains, at distances
far too great to allow of the male collecting them into one nest:
some authors have believed that the scattered eggs were deposited
for the young birds to feed on. This can hardly be the case in
America, because the huachos, although often found addled and
putrid, are generally whole.

When at the Rio Negro in Northern Patagonia, I repeatedly heard the
Gauchos talking of a very rare bird which they called Avestruz
Petise. They described it as being less than the common ostrich
(which is there abundant), but with a very close general
resemblance. They said its colour was dark and mottled, and that
its legs were shorter, and feathered lower down than those of the
common ostrich. It is more easily caught by the bolas than the
other species. The few inhabitants who had seen both kinds,
affirmed they could distinguish them apart from a long distance.
The eggs of the small species appeared, however, more generally
known; and it was remarked, with surprise, that they were very
little less than those of the Rhea but of a slightly different
form, and with a tinge of pale blue. This species occurs most
rarely on the plains bordering the Rio Negro; but about a degree
and a half farther south they are tolerably abundant. When at Port
Desire, in Patagonia (latitude 48 degrees), Mr. Martens shot an
ostrich; and I looked at it, forgetting at the moment, in the most
unaccountable manner, the whole subject of the Petises, and thought
it was a not full-grown bird of the common sort. It was cooked and
eaten before my memory returned. Fortunately the head, neck, legs,
wings, many of the larger feathers, and a large part of the skin,
had been preserved; and from these a very nearly perfect specimen
has been put together, and is now exhibited in the museum of the
Zoological Society. Mr. Gould, in describing this new species, has
done me the honour of calling it after my name.

Among the Patagonian Indians in the Strait of Magellan, we found a
half Indian, who had lived some years with the tribe, but had been
born in the northern provinces. I asked him if he had ever heard of
the Avestruz Petise. He answered by saying, "Why, there are none
others in these southern countries." He informed me that the number
of eggs in the nest of the petise is considerably less than in that
of the other kind, namely, not more than fifteen on an average, but
he asserted that more than one female deposited them. At Santa Cruz
we saw several of these birds. They were excessively wary: I think
they could see a person approaching when too far off to be
distinguished themselves. In ascending the river few were seen; but
in our quiet and rapid descent many, in pairs and by fours or
fives, were observed. It was remarked that this bird did not expand
its wings, when first starting at full speed, after the manner of
the northern kind. In conclusion I may observe that the Struthio
rhea inhabits the country of La Plata as far as a little south of
the Rio Negro in latitude 41 degrees, and that the Struthio
Darwinii takes its place in Southern Patagonia; the part about the
Rio Negro being neutral territory. M. A. d'Orbigny, when at the Rio
Negro, made great exertions to procure this bird, but never had the
good fortune to succeed. (5/16. When at the Rio Negro, we heard
much of the indefatigable labours of this naturalist. M. Alcide
d'Orbigny, during the years 1825 to 1833, traversed several large
portions of South America, and has made a collection, and is now
publishing the results on a scale of magnificence, which at once
places himself in the list of American travellers second only to
Humboldt.) Dobrizhoffer long ago was aware of there being two kinds
of ostriches, he says, "You must know, moreover, that Emus differ
in size and habits in different tracts of land; for those that
inhabit the plains of Buenos Ayres and Tucuman are larger, and have
black, white and grey feathers; those near to the Strait of
Magellan are smaller and more beautiful, for their white feathers
are tipped with black at the extremity, and their black ones in
like manner terminate in white." (5/17. "Account of the Abipones"
A.D. 1749 volume 1 English translation page 314.)

A very singular little bird, Tinochorus rumicivorus, is here
common: in its habits and general appearance it nearly equally
partakes of the characters, different as they are, of the quail and
snipe. The Tinochorus is found in the whole of southern South
America, wherever there are sterile plains, or open dry pasture
land. It frequents in pairs or small flocks the most desolate
places, where scarcely another living creature can exist. Upon
being approached they squat close, and then are very difficult to
be distinguished from the ground. When feeding they walk rather
slowly, with their legs wide apart. They dust themselves in roads
and sandy places, and frequent particular spots, where they may be
found day after day: like partridges, they take wing in a flock. In
all these respects, in the muscular gizzard adapted for vegetable
food, in the arched beak and fleshy nostrils, short legs and form
of foot, the Tinochorus has a close affinity with quails. But as
soon as the bird is seen flying, its whole appearance changes; the
long pointed wings, so different from those in the gallinaceous
order, the irregular manner of flight, and plaintive cry uttered at
the moment of rising, recall the idea of a snipe. The sportsmen of
the "Beagle" unanimously called it the short-billed snipe. To this
genus, or rather to the family of the Waders, its skeleton shows
that it is really related.

The Tinochorus is closely related to some other South American
birds. Two species of the genus Attagis are in almost every respect
ptarmigans in their habits; one lives in Tierra del Fuego, above
the limits of the forest land; and the other just beneath the
snow-line on the Cordillera of Central Chile. A bird of another
closely allied genus, Chionis alba, is an inhabitant of the
antarctic regions; it feeds on seaweed and shells on the tidal
rocks. Although not web-footed, from some unaccountable habit it is
frequently met with far out at sea. This small family of birds is
one of those which, from its varied relations to other families,
although at present offering only difficulties to the systematic
naturalist, ultimately may assist in revealing the grand scheme,
common to the present and past ages, on which organised beings have
been created.

The genus Furnarius contains several species, all small birds,
living on the ground, and inhabiting open dry countries. In
structure they cannot be compared to any European form.
Ornithologists have generally included them among the creepers,
although opposed to that family in every habit. The best known
species is the common oven-bird of La Plata, the Casara or
housemaker of the Spaniards. The nest, whence it takes its name, is
placed in the most exposed situations, as on the top of a post, a
bare rock, or on a cactus. It is composed of mud and bits of straw,
and has strong thick walls: in shape it precisely resembles an
oven, or depressed beehive. The opening is large and arched, and
directly in front, within the nest, there is a partition, which
reaches nearly to the roof, thus forming a passage or antechamber
to the true nest.

Another and smaller species of Furnarius (F. cunicularius),
resembles the oven-bird in the general reddish tint of its plumage,
in a peculiar shrill reiterated cry, and in an odd manner of
running by starts. From its affinity, the Spaniards call it
Casarita (or little housebuilder), although its nidification is
quite different. The Casarita builds its nest at the bottom of a
narrow cylindrical hole, which is said to extend horizontally to
nearly six feet under ground. Several of the country people told
me, that when boys, they had attempted to dig out the nest, but had
scarcely ever succeeded in getting to the end of the passage. The
bird chooses any low bank of firm sandy soil by the side of a road
or stream. Here (at Bahia Blanca) the walls round the houses are
built of hardened mud, and I noticed that one, which enclosed a
courtyard where I lodged, was bored through by round holes in a
score of places. On asking the owner the cause of this, he bitterly
complained of the little casarita, several of which I afterwards
observed at work. It is rather curious to find how incapable these
birds must be of acquiring any notion of thickness, for although
they were constantly flitting over the low wall, they continued
vainly to bore through it, thinking it an excellent bank for their
nests. I do not doubt that each bird, as often as it came to
daylight on the opposite side, was greatly surprised at the
marvellous fact.

I have already mentioned nearly all the mammalia common in this
country. Of armadilloes three species occur, namely, the Dasypus
minutus or pichy, the D. villosus or peludo, and the apar. The
first extends ten degrees farther south than any other kind; a
fourth species, the Mulita, does not come as far south as Bahia
Blanca. The four species have nearly similar habits; the peludo,
however, is nocturnal, while the others wander by day over the open
plains, feeding on beetles, larvae, roots, and even small snakes.
The apar, commonly called mataco, is remarkable by having only
three movable bands; the rest of its tesselated covering being
nearly inflexible. It has the power of rolling itself into a
perfect sphere, like one kind of English woodlouse. In this state
it is safe from the attack of dogs; for the dog not being able to
take the whole in its mouth, tries to bite one side, and the ball
slips away. The smooth hard covering of the mataco offers a better
defence than the sharp spines of the hedgehog. The pichy prefers a
very dry soil; and the sand-dunes near the coast, where for many
months it can never taste water, is its favourite resort: it often
tries to escape notice, by squatting close to the ground. In the
course of a day's ride, near Bahia Blanca, several were generally
met with. The instant one was perceived, it was necessary, in order
to catch it, almost to tumble off one's horse; for in soft soil the
animal burrowed so quickly, that its hinder quarters would almost
disappear before one could alight. It seems almost a pity to kill
such nice little animals, for as a Gaucho said, while sharpening
his knife on the back of one, "Son tan mansos" (they are so quiet).

Of reptiles there are many kinds: one snake (a Trigonocephalus, or
Cophias, subsequently called by M. Bibron T. crepitans), from the
size of the poison channel in its fangs, must be very deadly.
Cuvier, in opposition to some other naturalists, makes this a
sub-genus of the rattlesnake, and intermediate between it and the
viper. In confirmation of this opinion, I observed a fact, which
appears to me very curious and instructive, as showing how every
character, even though it may be in some degree independent of
structure, has a tendency to vary by slow degrees. The extremity of
the tail of this snake is terminated by a point, which is very
slightly enlarged; and as the animal glides along, it constantly
vibrates the last inch; and this part striking against the dry
grass and brushwood, produces a rattling noise, which can be

Online LibraryCharles DarwinThe Voyage of the Beagle → online text (page 10 of 51)