196 Wild Bird Guests 



martins, unless, of course, you wish to encourage 

 starlings or European sparrows. The two-room 

 houses for bluebirds, wrens, etc., which we see 

 on the market are never really occupied by two 

 families at the same time. 



Sometimes we see houses made with a good 

 deal of glass in the form of windows perhaps; 

 I do not remember having seen any house of this 

 kind occupied by birds. And it is inadvisable 

 to have more than one entrance to a room 

 or to have rooms in the same house connected 

 one with another. The extra doorways tend 

 to make the house draughty. If in any case 

 ventilation seems really necessary, holes should 

 be made above the entrance. 



But there are comparatively few of our birds 

 which take kindly to bird houses made on any 

 of these lines ; most of the others refuse to occupy 

 any ordinary hand-made nest box. Von Ber- 

 lepsch discovered this, and after years of expe- 

 riment decided that the only way to induce these 

 more fastidious birds to become his tenants, was 

 to give them nesting boxes practically like those 

 which woodpeckers, tits, and others make for 

 themselves by burrowing into the trunks and 

 branches of trees. So he invented a machine 

 which would hollow out a log in such a way that 

 the cavity was an exact facsimile of a wood- 



