al. V. ] 

 1905 J 



Campbell, Insectivorous Birds. 



Insectivorous Birds. 



{Extracts from a non-competitive paper written by A. G. Campbell, 

 Melbourne, for the .Nature Study Exhibition, Gcelong, Easter, 1905). 



The Economy of Birds. 



All nature is interdependent, and remarkably well able to balance 

 itself. When a form is past usefulness it disappears, and leaves 

 the field to the active, the quick-witted, the keen in life's pursuit, 

 who endeavour to forward the best interests of the species. 



Birds are one of the most striking groups in creation, and their 

 very existence proves their utility. Brought into the world not for 

 sport merely, or for beauty, the practicality of their use is beyond 

 all question. 



One form of life lives upon a lower type, this upon some other, 

 and so a check is kept. All increase and decrease with the food 

 supply, while those most preyed upon are usually most prolific. 

 The fight with circumstances always makes a race strong and 

 improves it, because in the struggle for existence the weak, those 

 insufficiently equipped, and the old are the first to perish. By this 

 process of the " survival of the fittest " the race improves. 



Birds have a definite purpose for existence in that they keep 

 down plants, insects, molluscs, reptiles, and small animals, and keep 

 down each other. We in Australia have not far to look for 

 examples of introduced life increasing beyond bounds. Evidences 

 are too abundant. In the rabbit and Cape weed it has been proved 

 how forms might become a burden when brought away from 

 natural restriction. 



Conversely, as much forethought should be shown in encouraging 

 insect-eating birds about the fields and forests as there is 

 required before introducing new life. If birds are driven away 

 entirely, as the country is cleared, it is little wonder that native 

 insects increase. Remove the natural restriction from anything 

 and the lower form becomes predominant. It may even enlarge 

 its tastes and feed upon plants, native, or possibly introduced, 

 which were before untouched, thus increasing in destructiveness 

 as well as in numbers. 



Birds, according to their food supply, may be classed thus : — 



A. Seed and fruit eating. 



B. Insectivorous. 



C. Omnivorous. 



D. Carnivorous. 



To the country generally the most important sections are the 

 second and third— viz., B. and C. To a certain extent seed and 

 fruit eating birds are of no small imj)ortance in spreading grass 

 seed and the seed of forest trees, yet the insectivorous section of 

 our avifauna has a more direct bearing upon the country's welfare, 

 inasmuch as they keep a check upon hordes of ravenous insects 

 with no small propensity for destroying the produce of the land. 



Omnivorous birds include many that are considered i)ests to 

 orchardists, farmers, and others, because at times they attack 



