53 



of the walls ; whereas broods that chanced to be hatehed in the artificial 

 stone or clay nesting- holes, with their thin walls, were exposed to abrupt 

 changes of temperature, extremes of heat and cold, and were thus 

 destroyed. 



The Seebach Station has also experimented with the clay " nesting- 

 urns," but they had to be used in conjunction with holes in wood, and 

 not by themselves. The want of success that attended the experiments 

 cannot, therefore, be regarded as conclusive until the urns have been 

 used alone without any other nesting-arrangements, especially after a 

 severe winter, for all nest ing- holes, whether of wood or clay, must be 

 tested not only for breeding purposes, but also as places for sleeping 

 in in winter. The old-fashioned clay " boxes," which were less deep, 

 and had, like all the former boxes, a flat bottom (the interior of 

 Schliiter's nesting- urns which we are discussing here, is an exact 

 reproduction of the Berlepsch nest ing- boxes), have by no means fulfilled 

 the purpose for which they were int ended, though their walls were 

 much thicker, as was specially apparent during the severe winter of 

 1884-85. In the early spring there were found in them many tits, 

 nuthatches, tree-creepers, and even several tree-sparrows and a robin, 

 that had been frozen to death. In my opinion the use of the thin- 

 walled clay-urns will have similar deplorable results. But in 

 accordance with the von Berlepsch principle, only to state what has 

 been confirmed by actual results, we are at present, unfortunately, 

 not in a position to attack what will, without doubt, prove a source 

 of great danger to our birds. 



We should, however, like to make it quite clear to the amateur 

 that even though very favourable results are obtained in the future, 

 the clay " boxes " can never be more than a makeshift for the wooden 

 ones for those breeders in holes that build nests. It is absolutely 

 impossible that clay " boxes " should ever become a perfect substitute 

 for wooden ones. We shall continue our investigations. 



