410 



USEFUL BIRDS. 



fectly smooth surface. Nesting boxes mounted on poles may 

 be guarded in this way. Zinc is the best material. A wide 

 piece of wire netting, shaped like a hat brim, and fastened 

 around a tree, will prevent cats and squirrels from climb- 



ing it. 



A smooth, 

 tall, slim pole, made 

 of a peeled sapling 

 pine set in the open, 

 is rarely climbed by 

 cats or squirrels. 



Thick thorn bushes 

 often serve as safe 

 nesting places for 

 birds. Bundles of 

 thorny sticks tied 

 around tree trunks 

 will keep cats out of 

 the trees. An island 

 in a small artificial 

 pond is also a refuge 

 from cats. The best 

 cat-proof fence for a city garden is that used by Mr. William 

 Brewster at Cambridge. It is made of wire netting some 

 six feet in height, surmounted by a fish seine of heavy twine, 

 which is fastened to the top of the wire. The top of the net is 

 then looped to the ends of long, flexible garden stakes. This 

 fabric gives beneath any weight, and offers so unstable a foot- 

 ing that no cat ever succeeds in scaling it. Mr. Brewster's 

 garden has become famous for the numbers of birds that breed 

 there, and the migrants that visit it year by year. 



Pig. 171. — Zinc bands to prevent cats or squirrels 

 from climbing trees or poles. 



THE PROTECTION OF FARM PRODUCTS FROM BIRDS. 



Serious losses sometimes occur from injury inflicted on 

 crops or poultry by birds. It is well to remember, how- 

 ever, that, while the harm done by birds is conspicuous, 

 the compensating good that they do is usually unnoticed. 

 In most cases it is best not to kill them, but to protect both 

 birds and crops ; for by killing too many birds we may dis- 

 turb the biological equilibrium, and bring about a greater 



