402 BIEDS OF NORFOLK. 



attributing it to atmosplierical influences^ such, as ^Hhe 

 continuance of a week's violent north-east wind;" 

 others, " to the colonization of the valley of the Amoor 

 by the Eussians, and the probably increased amount of 

 land sown with seed along the roads leading from 

 thence to European Russia;" others, again, to the 

 effects of a supposed drought in the countries where 

 this species mostly abounds. After reading, however, 

 Mr. Newton's very plausible reasons for not attributing 

 the ^^ exodus" to any of the above causes, or at least 

 for not receiving any one of them as the primary cause, 

 I think that most people will concur in his own 

 expressed opinion, that this ^^ wonderful movement" is 

 attributable " to the natural overflow of the population 

 of Syrrhaptes, resulting from its ordinary increase." In 

 support of these views he refers to the habits of this 

 species as observed in the basin of the Tarei-nor, a 

 lake situated in Dauria, about fifty degrees north and 

 one hundred and sixteen degrees east (from Greenwich), 

 under most favourable circumstances, by Herr Eadde 

 in the spring of 1856. There it arrives as one of the 

 earliest migrants by the 10th (22nd) of March, and two 

 immense flocks discovered in the island of the Tarei, 

 consisting each of at least a thousand birds, after 

 frequent disturbance, suddenly left the district altogether 

 to appear no more during that season, showing, as Mr. 

 Newton remarks, " that Syrrhaptes is subject to sudden 

 movements on a very large scale, and of a kind which, 

 at first sight, appear almost capricious." Its wondrous 

 powers of flight must protect all but the weaker members 

 from the attacks of falcons, while it is also known, from 

 Herr Radde's observations, that the time of incubation 

 and the growth of the young is "short in comjiarison 

 with what it is in most ground-breeding birds," all points 

 indicative of a considerable and rapid increase of the 

 race, and the necessity from time to time of extending 



