CHAPTER V.

The next day the ship was off Rio, and immediately sent her boats for provisions and supplies; the passengers did not land, as the captain stated that he would not stay an hour longer than was necessary, and on the second evening after their arrival they again made sail for the Cape.

The gulls were flying in numbers astern of the ship, darting down and seizing every thing edible which was thrown overboard, and the conversation turned upon aquatic birds.

“What difference is there in the feathers of aquatic birds and others?” inquired Alexander; “a hen, or any land bird, if it falls into the water, is drowned as soon as its feathers are saturated with the water.”

“There is, I believe, no difference in the feathers of the birds,” replied Mr. Swinton; “but all aquatic birds are provided with a small reservoir, containing oil, with which they anoint their feathers, which renders them water-proof.  If you will watch a duck pluming and dressing itself, you will find it continually turns its bill round to the end of its back, just above the insertion of the tail; it is to procure this oil, which, as it dresses its feathers that they may carefully overlap each other, it smears upon them so as to render them impenetrable to the water; but this requires frequent renewal, or the duck would be drowned as well as the hen.”

“How long can a sea-bird remain at sea?”

“I should think not very long, although it has been supposed otherwise; but we do not know so much of the habits of these birds as of others.”

“Can they remain long under water?”

“The greater portion of them can not; ducks and that class, for instance.  Divers can remain some time; but the birds that remain the longest under water are the semi-aquatic, whose feet are only half-webbed.  I have watched the common English water-hen for many minutes walking along at the bottom of a stream, apparently as much in its element as if on shore, pecking and feeding as it walked.”

“You say that aquatic birds can not remain long at sea,—­where do they go to?”

“They resort to the uninhabited islands over the globe, rocks that always remain above water, and the unfrequented shores of Africa and elsewhere; there they congregate to breed and bring up their young.  I have seen twenty or thirty acres of land completely covered with these birds or their nests, wedged together as close as they could sit.  Every year they resort to the same spot, which has probably been their domicile for centuries,—­I might say since the creation.  They make no nests, but merely scrape so as to form a shallow hole to deposit their eggs.  The consequence of their always resorting to the same spot is that, from the voidings of the birds and the remains of fish brought to feed the young, a deposit is made over the whole surface, a fraction of an inch every year, which by degrees increases until it is sometimes twenty