870 TROPICAL NATURE v 
turkey, and the pea-fowl go on feeding while the male is dis- 
playing his finery ; and there is reason to believe that it is 
his persistency and energy rather than his beauty which 
wins the day. Again, evidence collected by Mr. Darwin 
himself, proves that each bird finds a mate under any 
circumstances. He gives a number of cases of one of a 
pair of birds being shot, and the survivor being always 
found paired again almost immediately. This is sufficiently 
explained on the assumption that the destruction of birds by 
various causes is continually leaving widows and widowers in 
nearly equal proportions, and thus each one finds a fresh 
mate; and it leads to the conclusion that permanently 
unpaired birds are very scarce, so that, speaking broadly, 
every bird finds a mate and breeds. But this would almost 
or quite neutralise any effect of sexual selection of colour or 
ornament, since the less highly-coloured birds would be at 
little or no disadvantage as regards leaving healthy offspring. 
If, however, heightened colour is correlated with health and 
vigour ; and if these healthy and vigorous birds provide best 
for their young, and leave offspring which, being equally 
healthy and vigorous, can best provide for themselves—which 
cannot be denied—then natural selection becomes a preserver 
and intensifier of colour. 
Another most important consideration is, that male butter- 
flies rival or even excel the most gorgeous male birds in 
bright colours and elegant patterns ; and among these there is 
literally not one particle of evidence that the female is influ- 
enced by colour, or even that she has any power of choice, 
while there is much direct evidence to the contrary (Descent 
of Man, p. 318). The weakness of the evidence for conscious 
sexual selection among these insects is so palpable that Mr, 
Darwin is obliged to supplement it by the singularly incon- 
clusive argument that, “Unless the female prefer one male to 
another, the pairing must be left to mere chance, and this 
does not appear probable” (ic. p. 317). But he has just 
said: “The males sometimes fight together in rivalry, and 
many may be seen pursuing or crowding round the same 
female;” while in the case of the silk-moths, “the females 
appear not to evince the least choice in regard to their part- 
ners.” Surely the plain inference from all this is, that males 
