Habit and Instinct. 445 



completely instinctive avoidance, by birds and lizards, of 

 insects with warning coloration. That the avoidance is 

 not perfectly instinctive is shown by the fact that young 

 birds sometimes taste these caterpillars or insects. But 

 a very small basis of experience, often a single case, is 

 sufficient to establish the association. And in young 

 chicks the avoidance of bees and wasps seems to be perfectly 

 instinctive. The effects on the young birds, however, can 

 hardly be of elimination value. Mr. Poulton offered un- 

 palatable insects "to animals from which all other food 

 was withheld. Under these circumstances, the insects 

 were eaten, although often after many attempts, and 

 evidently with the most intense disgust." *' I have caused 

 bees to sting young chickens ; the result was extreme dis- 

 comfort, but in no cases permanent injury or death. If, 

 then, the instinct is not of elimination value, that is to say, 

 not such as to save the possessors from elimination, how 

 can it have been established by natural selection ? And if 

 not due to natural selection, to what can it be due, save 

 inherited antipathy ? 



Natural selection is such a far-reaching and ubiquitous 

 factor in organic evolution, that it is not likely that many 

 cases can be found in which the play of elimination can be 

 rigidly excluded. But there are not a few in which elimina- 

 tion does not appear to be the most important factor. Mr. 

 G. L. Grant has recently observed that the sparrows near 

 Auckland, New Zealand, have taken to burrowing holes in 

 sand-cliffs, like the sand-martin. The cliff-swallow of the 

 Eastern United States has almost ceased to build nests in 

 the cliffs, like its progenitors, and now avails itself of the 

 protection afforded by the eaves of houses. The surviving 

 beavers in Europe are said to have abandoned the instinct 

 of building huts and dams. The race being no longer 

 sufficiently numerous to live in communities, the survivors 

 live in deep burrows. In Russian Lapland, under the 

 persecution of hunters, the reindeer are reported to be 

 abandoning the tundras, or open lichen-covered tracts, for 



* " Colours of Animals," p. 180. 



