52 
NORTH BORNEO. 
when compared with the now thoroughly explored European area it will be found to contain 
many more species. A list of Bornean birds compiled by Mr. A. H. Everett contains some 
580 species, including a few later additions; while Mr. H. E. Dresser’s list of the whole 
Western Palaearctic Region totals some 623 species. The Bornean list is less likely to be 
augmented by additions from the neighbouring islands, as it is surrounded, with the 
exception of Celebes on its east coast, by countries which contain an almost identical ornis. 
During the northern winter a great many migratory species are added to the list, the order 
of Limicolce alone adding 38 species. The great region selected by Mr. Dresser receives 
annual additions from all its boundaries, even including America ; and it will be seen that 
many species are mere stragglers, and more than equalize the Bornean additions through 
migration. Thus, having shown that a tropical island contains in comparison to an equal 
area in temperate climes nearly double the number of species, the question to be answered 
is, Where does all this mighty host hide itself 1 Some travellers attribute the scarcity in 
numbers of birds in a tropical forest to the great height of the forest trees, and tell us that 
up in the roof of the primaeval forest there is another world full of life, which man cannot 
reach ; but I myself am inclined to think this greatly exaggerated, as I have attentively 
examined the tops of the forest trees for hours, and noticed neither bird, butterfly, nor 
flower. My experience of collecting in these regions has led me to believe that though 
species are more numerous than in colder climates, the individuals of each species are fewer 
in number, with the exception of a few specially protected genera; and after these have 
been collected the rest come in very slowly indeed ; and yet the island of Borneo, by no 
means thoroughly explored, can boast of 580 species of birds and some 600 species of 
butterflies. The reason of this scarcity of individuals in most species is due, firstly, to their 
low rate of increase ; secondly, to their numerous enemies; and, thirdly, to the fact that 
few tropical species are gregarious, and the domain over Avhich they wander is so vast that 
many species are seldom met with. 
Firstly, let us consider some of the reasons which tend to keep down the increase of 
most species of birds. One peculiar fact that at first I could not understand was that birds 
in the tropics seldom lay more than two eggs. At first when I found a nest with two eggs 
1 used to wait until the eggs were almost hatched for the other three which should complete 
the sitting; but it soon dawned upon me that two eggs Avere all I need expect to find in a 
nest in these latitudes. So, being of an inquiring turn of mind, I asked the natives about 
the fecundity of their domestic animals—dogs, cats, and pigs,—and found that in every case 
the rate of reproduction AA'as far beloAv that of colder climates. 
The families of natives are very small: in one or tAVO instances I have known them to 
contain eight or more by one mother, but many Avomen have only three or four, most one 
or two children ; and it is by no means uncommon to find them childless. The cause of 
this Ioav rate of increase has been ascribed by many Avriters to the hard work performed 
by the Avomen of barbaric races; but to my mind this has nothing to do Avith it. I 
believe the reason is entirely to be attributed to the Ioav degree of fecundity of such 
races, brought about by the climate, and aggravated by the difficulty of finding sufficiently 
nourishing food during certain periods. Besides this, infant mortality is decidedly above the 
average, there being no knoAAdedge of medicine amongst such men. FeAV tribes increase 
much in number, an epidemic breaking out retards any increase for many years ; and there 
