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LliRARY' 



THE OTTAWA NATURALIST 



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VOL. XXXII. 



JANUARY, 1919. 



No. 7. 



BIRD-HOUSES AND THEIR OCCUPANTS.* 



Bv P. A. Taverner. 



Like Desdemona, we "have a divided duty". On 

 the one hand to cultivate the land cleanly, and on 

 the other, to attract birds to it. These are opposed 

 duties. If we cut the dead wood from our wood 

 lots, parks, and groves; clean out, sterilize, and fill 

 retting spots in limb and trunk with concrete, we 

 deprive many birds of nesting facilities. If we 

 clear out tangled brush, cultivate to the fence lines, 

 open the ground about young, second-growth 

 plantations, and drain the last marshy spots, we 

 deprive many of necessary cover and the food that 

 goes with it. Insect, weed, and small mammal pests 

 may be reduced; but so, inevitably, will the birds 

 as well. The consequence is likely to be that, 

 whilst our control of pests on the whole will be 

 better, we shall be subject to occasional sporadic 

 outbursts of species that are not subject to these par- 

 ticular methods of control. Whilst the study of their 

 food habits may suggest that birds do not usually 

 partake largely of those insects (for example, the 

 potato bug) whose numbers commonly assume plague 

 proportions, it is also evident that insects that birds 

 systematically feed upon, rarely become plagues. 

 We know, to our sorrow, the few instances where 

 our control is inadequate, but we have no means 

 of knowing the innumerable cases where it has 

 warded off disaster. 



The real value of birds as guardians of our fields 

 and gardens is not in the individual species but in 

 the aggregate, each filling its own narrow field, yet 

 all combined, covering every weak point. The 

 swallows hawk through the upper air; the vireos, 

 orioles, and tanagers haunt the tree tops; the wood- 

 peckers and chickadees, the limbs and bark crevices; 

 whilst thrushes e.xamine the debris of wocded 

 grounds and the sparrows and meadow larks scour 

 open fields and shrubbery tangles. In fact at no 

 period of their life cycles are insects free from 

 avian attack flying, creeping, hiding or buried in 

 the ground or in solid wood there are species of 

 birds fitted for and eager to attack them. Should 

 any one class of these, our unpaid assistants, be 



prevented from functioning, an opening is left in our 

 defence that may be an Achilles' heel to our un- 

 doing. If we turn our woods into groves, meadows 

 into lawns, and tangles into formal shrubbery some- 

 thing of this sort is possible, unless compensations are 

 provided. In the home grounds and city streets 

 and parks the ideal of clean cultivation is most 

 nearly approached and here it is the more necessary 

 to provide artificially the necessities of bird life that 

 are missing. 



Bird boxes will largely compensate for natural 

 cavities in trees and carefully selected plantings of 

 shrubbery and decorative flowers in naturalistic de- 

 sign will supply cover and fruit and seed food. If 

 we fortunately succeed in reducing insects to a point 

 dangerous to bird welfare the deficiency can be 

 supplied by scraps of animal matter presented at 

 feeding stations, on shelves, or in shelters. In these 

 ways only can we partially compensate for our 

 interference with the natural scheme and retain wild 

 birds under conditions of high cultivation. In- 

 cidentally, as the home lot is the first to be made 

 atractive to birds, we draw their interesting person- 

 alities close about us, and in place of having to 

 tramp miles to their secluded haunts, decoy them 

 to our very windows where they can be enjoyed 

 practically continuously instead of occasionally, in- 

 timately instead of distantly, and at ease instead of 

 by exertion. Any one of the methods above sug- 

 gested requires, for intelligent development, a paper 

 to itself; and the first, only, the building of bird 

 houses and boxes, will be here discussed. 



The first thing to consider in building a bird box 

 is the species for which it is designed. Each has its 

 own requirements and though its necessities are more 

 or less elastic the more nearly we fulfil the bird's 

 ideal the more successful we shall be in getting it 

 to use what we provide. In short we must cater 

 to the customs and idiosyncrasies of our tenants and 

 not to our own ideas of convenience and beauty. It 



*Published by permission of tlie Geological Survey, 

 lllustration.s by courtesy of the Geological Survey. 



