112 STUDIES IN BIRD-MIGRATION 



found among a flock of Twites on the stubbles. A 

 scarlet bird reported and described to me during my 

 visit in the autumn of 1908 was, no doubt, an adult 

 male of this species. 



LoxiA cuRviROSTRA, Common Crossbill, — During the 

 remarkable irruption of Crossbills from the Continent in 

 the summer of 1909, Fair Isle received many of the 

 visitors. These birds were first detected on 23rd June, 

 and their numbers increased gradually until loth July, 

 as if the birds had arrived in a series of waves, as many 

 as 300 being seen on a single day. The immigrants 

 remained on the island throughout July, but their 

 numbers fell off towards the end of the month. They 

 were observed in some abundance, in small scattered 

 parties, during the whole of August. Later they became 

 gradually scarcer, only two or three being seen in 

 September ; and the last of the hundreds once present 

 was seen on 2nd October, feeding on the head of 

 a thistle. During their sojourn they frequented all 

 parts of the island : the faces of the great cliffs, the 

 cultivated land, the grassy slopes, and the high heathery 

 ground. On the latter they fed on the unripe fruit of 

 the crowberry ; elsewhere on the seeds of grasses and 

 other plants, and on the heads of thistles. At first 

 they seemed to thrive, but later many perished, their 

 dead bodies being found in the plots of potatoes, etc. 



A small number made their appearance in the 

 summer of 19 10, the first of these visitors being an 

 adult male seen on 20th June. None appear to have been 

 seen afterwards until 8th August, when nine came under 

 notice, and the birds were seen daily in small numbers 

 down to 19th September. 



Another immigration took place, in the summer of 



