ECOLOGICAL 215 



insects. Thus the common Yellow Bunting or Yellow-hammer, 

 which depends on seeds and small fruits in winter, is largely insecti- 

 vorous in summer, and feeds its young on insects. The fact that it, 

 like the Hedge-sparrow, is also fond of spiders, may be noted as 

 an instance of the difficulty of balancing pros and cons, for 

 spiders are very useful in checking the multiplication of small 

 insects. 



In many parts of the country where the Yellow-hammer used 

 to be very common, there is now a marked scarcity. This is ascribed 

 by some to the fact that there is of recent years so little horse-dung 

 on the roads; it used to be a common sight to see the Yellow- 

 hammers picking up the undigested grains of oats. 



In Conclusion, it is quite certain that the food of many wild 

 birds consists largely of injurious insects which are a continual 

 menace and involve a huge annual loss which no country can 

 afford. Thus there might be mentioned from the long list the follow- 

 ing representative birds: titmice, lapwings, hedge-sparrows, red- 

 breasts, skylarks, thrushes, wagtails, warblers, pipits, and fly- 

 catchers. These and scores of other birds are worthy of preservation 

 on grounds of utility — let alone higher values — and one way of 

 securing their survival is to refrain from being over-zealous in 

 doing away with more or less harmless shelters. 



THE INTRICACY OF LIFE.— From the illustrations given it 

 is plain that the old-fashioned Natural History, which needs no 

 apology when we think of masters Hke Reaumur and Gilbert White, 

 is being replaced by the modern sub-science of Ecology, which 

 expresses the same ambition to understand living creatures in the 

 plural and in relation to their surroundings, both animate and 

 inanimate. It is what Semper called "the higher physiology", the 

 study of life as it is lived in Nature, where the circle of each indi- 

 vidual's interests is intersected by many other circles — such as 

 kindred, members of the same species, neighbours, competitors, 

 deadly enemies, parasites, symbions, and so forth. To Pearse and 

 to Elton we owe two good English- written books on Animal 

 Ecology, and everyone knows Tansley's Plant Ecology. All we wish 

 to do here is to emphasise the general impression — the intricacy of 

 life's inter-relations. 



One of the main tasks of ecology is to decipher the patterns in 

 the web of life, and as the inquiry is being pursued with precision 

 and penetration it is becoming plain that the intertwining of the 

 vital threads is even more intricate than was supposed by the 

 old-fashioned Natural History with all its scrutinising insight. 

 Darwin was a modern ecologist in his appreciation of the work of 

 earthworms, so much deeper and more convincing than Gilbert 

 White's anticipations. 



