118 INTEODUCTION OF BIRDS. 



against pursuit by their enemies, which holes and dens afford to 

 burrowing animals and to some larger beasts of prey. The egg 

 is exposed to many dangers before hatching, and the yomig bird 

 is especially tender, defenceless and helpless. Every cold rain, 

 every violent wind, every hailstorm during the breeding season, 

 destroys hundreds of nesthngs, and the parent often perishes with 

 her progeny while brooding over it in the vain effort to protect 

 it,* The great proportional numbers of birds, their migratory 

 habits, and the ease with which by their power of flight they 

 may escape most dangers that beset them, would seem to secure 

 them from extirpation, and even from very great numerical re- 

 duction. But experience shows that when not protected by law, 

 by popular favor or superstition, or by other special circum- 

 stances, they yield very readily to the hostile influences of civiliz- 

 ation, and, though the first operations of the settler are favorable 

 to the increase of many species, the great extension of rural and 

 of mechanical industry is, in a variety of ways, destructive even 

 to tribes not directly warred upon by man.f 



at least west of Russia, until the year above mentioned, when many flocks of 

 twenty or thirty, and even a hundred individuals, were seen in Bohemia, Ger- 

 many, Holland, Denmark, England, Ireland and France. A considerable 

 flock frequented the Frisian island of Borkum for more than five months. It 

 was hoped they would breed and remain permanently in the island, but this 

 expectation has been disappointed, and the steppe-grouse seems to have dis- 

 appeared again altogether. 



* It is not the unfledged and the nursing bird alone that are exposed to 

 destruction by severe weather. Whole flocks of adult and strong-winged 

 tribes are killed by hail. Severe winters are usually followed by a sensible 

 diminution in the numbers of the non-migrating birds, and a cold storm in 

 summer often proves fatal to the more delicate species. On the 10th of June, 

 184-, five or six inches of snow fell in Northern Vermont. The next morning 

 I found a humming-bird killed by the cold, and hanging by its claws just be- 

 low a loose clapboard on the wall of a small wooden building where it had 

 sought shelter. 



f Ltell, Antiquity of Man, p. 409, observes : " Of birds it is estimated that 

 the number of those which die every year equals the aggregate number by 

 which the species to which they respectively belong is, on the average, per- 

 manently represented." 



A remarkable instance of the influence of new circumstances upon birds was 

 observed upon the establishment of a lighthouse on Cape Cod some years 

 since. The morning after the lamps were lighted for the first time, more than 

 s hundred dead birds of several different species, chiefly water-fowl, were 



