60 Dr. Jenner on the Migration of Birds. 



our domestic birds above mentioned, proves the stimulus, I 

 conceive, to certain unseasonable migrations, and accounts 

 for the irregularity first noticed. The same argument is of 

 course applicable to the premature appearance of any other 

 migrating birds. The month of March sometimes affords us 

 warm weather for several successive days." At this time I 

 have often seen the snake basking under a hedge. The lizard, 

 too, has been invited from his cold retreat; but never could 

 I see die swallow or the martin, although I have taken every 

 opportunity of looking for them during the transient sunshine, 

 and made diligent inquiries of others. At the further advance- 

 ment of spring, often in April, when, from the long prevalence 

 of north-easterly winds, the weather becomes unseasonably 

 cold, and even frosty, swallows, martins, and other early mi- 

 grators appear among us. But they soon experience the 

 hardships of an inhospitable reception; the insects that should 

 afford them food being still in a state of torpor in their wintry 

 recesses; and, unless called forth by some agreeable change in 

 the air, the unfortunate birds perish for want of food. This 

 I have known happen during an inclement spring, and have 

 picked up starved martins under their nesting places, and 

 willow wrens, which have perished under hedges, through a 

 want of succours. 



Unlike the migrating birds that winter with us, of which I 

 shall speak in a subsequent part of this paper, the spring or 

 summer birds do not possess the disposition to change the 

 scene and seek a more genial clime, when this country is so 

 overspread by frost as to deny them their common supplies. 

 This, I imagine, will admit of an easy explanation. The win- 

 ter birds require nothing here but food and shelter. Our 

 summer visitors come for more various and important pur- 

 poses. Had they, like the former birds, been endowed with 

 a disposition to wander on certain changes of the atmosphere, 

 the great design of their migration, as it must have proved 

 fatal to the business of incubation and the rearing of their 

 young, would have been frustrated. It may be worthy of re- 

 mark, that both the summer and winter migrating birds are, 

 on their arrival here, well received by the domestic natives, 

 and neither create quarrels nor excite fears. The redstart 

 builds its nest in the same tree with the titmouse, and the red- 

 wing feeds peaceably in the same meadow with the starling. 



[To be continued.] 



VIII. Ob- 



