The Solomon Islands and Their Natives

by H. B. Guppy

[460] Journ. für Ornithologie, 1859, pp. 112-115; also Proceed. Zoolog. Soc., 1885, p. 610.

[461] “A General System of Botany,” by Le Maout and Decaisne: London, 1873, p. 983.

[462] “Nature,” Nov. 27th, 1884.

[463] Proc. Zoolog. Soc., 1884: p. 532.

[464] Proc. Zool. Soc., 1884, p. 532.

[465] “Nature,” Dec. 11th, 1884 and May 27th, 1886.

A species of Collocalia, which usually frequents inaccessible sea-caves and cliffs, is frequently to be observed on the coasts of the islands of this group. The natives of Treasury Island call this bird “kin-kin;” but they have no knowledge of the nutrient qualities of the substance of which it builds its nest, and they were much amused when I told them of its being a Chinese luxury. I only came upon the nests of this bird on one occasion, and that was in some caves on Oima Atoll in Bougainville Straits. A description of these caves will be here unnecessary. As in the instance of the birds of the Borneo caverns, these swiftlets shared their retreats with a number of large bats, the accumulation of whose droppings had produced a thick reddish-brown deposit on the floors of the caves. The nests, which were formed for the most part of fibres derived evidently from the vegetable drift[466] at the mouths of the caves, were thickly incrusted with the gelatinous incrustation which projected as winglets from the sides and fastened them to the rock.

[466] The husks of pandanus seeds more particularly.

A reddish soft gelatinous incrustation occurred on the faces of some of the cliffs in the vicinity of the caves. It was composed of an aggregation of the cells of a microscopic unicellular alga which measure ¹⁄₂₅₀₀ of an inch in diameter. Unfortunately the specimens of this growth which I collected have been mislaid, but there can be little doubt that it is similar to the “fungoid growth” which Mr. Pryer describes in connection with the Borneo caves, and which, through the kindness of Mr. George Murray, I had the opportunity of seeing at the British Museum. On the faces of the coral limestone cliffs of some islands, such as on the east coast of Santa Anna, a like growth occurs in considerable quantity. In its freshest condition, it may be described as a reddish-yellow, gum-like substance forming a layer ¹⁄₄ to ¹⁄₈ of an inch in thickness. Where it incrusts the overhanging face of a cliff, it is more fluid in consistence and sometimes hangs in little pendulous masses, one to two inches in length, the extremities of which are often distended with water. This alga decomposes the hard coral limestone, making the surface of the rock soft and powdery. All stages in the growth of this substance may be observed. The older portions are very dark in colour and have a tough consistence; and in the final stage it occurs as a black powder covering the rock surface. On examining this alga with the microscope, I found it to be formed almost entirely of granular matter apparently resulting from the death of the cells; whilst the presence of a few cellular bodies alone gave me an indication of its true nature.

From my observations relating to the subject of the edible bird’s nest, it may be therefore inferred that in the Solomon Islands, as in Borneo, the occurrence of these nests is associated with the presence of a protophytic alga, which incrusts the rocks of the locality as a gelatinous or gum-like substance. Whether or not the birds employ this material in forming their nests, is a question which would appear to have been already answered in the negative; but it seems to me that those who hold that this material is used for this purpose might justly claim that the final judgment should be suspended, until a chemical examination of this vegetable substance has been made with the object of determining whether it might not yield a material closely resembling mucin. Amongst the nitrogenous constituents of plants occurs the so-called vegetable albumen, which in its chemical composition and in its behaviour with re-agents does not differ materially from the blood-albumen of the animal organism, of which in fact it is the source. In suggesting, therefore, that a vegetable mucin may be found in this low plant-growth, I do not pass beyond the bounds of probability.[467]