IC)2 1 1 i:\siiaw on Causes affecting the Decrease of /lira's. 



Old age among birds, as elsewhere throughout animated 

 beings, is instrumental as a check on increase, and doubtless 

 many birds survive the various dangers to which bird life is heir 

 to and pay the hist great debt from the decay of their vital 

 powers. But the number of deaths from disease and old age 

 doubtless varies within comparatively narrow limits, and hence 

 either alone or combined with natural enemies cannot furnish the 

 cause we seek. Of death-dealing causes none is so curious as 

 that modern invention the telegraph wire. On the plains where 

 high winds prevail and where there is insufficient shelter many birds 

 have been noticed under the wires, dead or crippled from being 

 blown against them. Under such circumstances it has proved 

 a source of considerable mortality among small birds. But 

 when the wires are first put up in a neighborhood it is by no 

 means a rare accident for birds of various kinds to fly against 

 them in calm weather, evidently not seeing, or at least not com- 

 prehending, the nature of the obstruction. As might be expect- 

 ed from the height at which it flies and the time of day when 

 most active, the Woodcock is particularly prone to this sort of 

 accident, and scores of this bird have been reported in the 

 sporting papers as being found dead or disabled under newly 

 laid wires. It bears witness to the intelligence of birds and 

 their power to profit by the lessons of experience that in a very 

 short time they learn to appreciate the danger and to avoid it by 

 flying above or below the obstruction, so that they rarely suffer 

 even in high winds. 



Storms, especially when they are prolonged and accompanied 

 by sudden and excessive change of temperature, are directly 

 responsible for important changes in the relative numbers in the 

 species of a district, and not a few instances could be cited where- 

 certain species have been entirely exterminated from a locality. 



The less hardy of our small Insectivores are specially liable to 

 disasters of this kind, particularly in the spring, during or just 

 subsequent to their return from their tropical winter quarters. 

 Indeed, taking our country at large, it is probable that scarcely 

 a year passes without the loss in one or several districts of great 

 numbers of birds from this cause. Sometimes the storm-visited 

 area is small, and occurring early in the season the storm works 

 injury to comparatively few of the earlier migrants. But occa- 

 sionally it is wide-spread in its effects and, coming in the height 

 of the migration, destroys great numbers of individuals and affects 

 a considerable number of species. 



