How Animals Work. 



outside of the nest, whilst she works on the inside, 

 drawing in fibres pushed in by the male, reinserting 

 them in their proper place, and smoothing all carefully. 

 Considerable time is spent in completing this part of 

 the nest, the egg chamber formed on one side of the 

 loop and the tubular entrance at the other, after which 

 there appears to be an interval of rest. It is at this 

 stage of the work from the formation of the loop to 

 the time that the egg compartment is ready that the 

 lumps of clay are stuck on about which there have been 

 so many and conflicting theories. The original notion 

 derived entirely, I believe, from the natives was 

 that the clay was used to stick fire-flies on, to light up 

 the apartment at night. Layard suggests that the bird 

 uses it to sharpen its bill on ; Burgess, that it serves 

 to strengthen the net. I, of course, quite disbelieve 

 the fire-fly story, and doubt the other two suggestions. 

 From an observation of several nests, the times at which 

 the clay was placed in the nests, and the position occu- 

 pied, I am inclined to think that it is used to balance 

 the nest correctly, and to prevent its being blown 

 about by the wind. In one nest lately examined there 

 was about three ounces of clay in six different patches. 

 It is generally believed that the unfinished nests are 

 built by the male for his own special behoof, and that 

 the pieces of clay are more commonly found in them 

 than in the complete nest. I did not find this the case 

 at Rangoon, where my opportunities for observing the 

 bird were good, and believe rather that the unfinished 

 nests are either rejected, if built early in the breeding 

 season, or if late, that they are simply the efforts of 

 that constructive faculty which appears, at this season, 



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