CROSSBILL 145 



the bill may be, straight or curved, or broad and flat, or conical, or 

 hooked, the two mandibles correspond, and fit when closed like box 

 and lid. In this bird both mandibles have prolonged curved points, 

 and cross each other, much as the two forefingers of our hands cross 

 when the fingers are loosely linked together. A full description of 

 this form of beak and its use as a seed-extractor, together with an 

 admirably written history of the common crossbill, is contained in 

 the second volume of YarrelTs great work (fourth edition). 



The crossbill is also remarkable on account of the changes of 

 colour it undergoes and of the brightness of its colours. These are 

 birds of the sombre pine- woods, inhabiting high latitudes ; but in their 

 various greens and reds and yellows they are like tanagers and other 

 tropical families, and form an exception to the rule that birds of 

 brilliant plumage are restricted to regions of brilliant sunlight. 



No fewer than four species of this genus (Loxia) figure in the 

 list of British birds ; three of these may be dismissed in a few 

 words : 



Parrot crossbill (Loxia pittyopsittacua) breeds in the pine-forests 

 of Scandinavia and northern Eussia, and is known in England as a 

 rare straggler. It is scarcely distinct, specifically, from the common 

 crossbill. 



White- winged crossbill (Loxia leucopUra), a North American 

 species, once obtained in England. 



Two-barred crossbill (Loxia bifasdata) a Siberian species ; a 

 rare straggler to England and Ireland. 



The fourth species (the common crossbill) has a better title to 

 figure as a British species, and its winter visits to this country are 

 much more frequent, although irregular ; and it also breeds with us 

 hi some localities in Scotland, probably every year, and has also 

 bred intermittingly in many districts in England, even so far south 

 as Bournemouth. The reason of its irregularity in visiting our 

 shores is that the crossbill is one of those species that do not go 

 farther from home than they are compelled by severe cold and scarcity 

 of food. Driven from home they become ' gipsy migrants,' and may 

 be very abundant with us one year, and not one appear the following 

 season, or for several seasons. At all times of the year the cross- 

 bill is gregarious in its habits. Throughout the summer it is seen 

 in small parties ; when the breeding season is over these begin to 

 move about, accompanied by the young birds, and join with other 

 parties, and as the season progresses the flock grows by process of 

 accretion until it may number many hundreds. At this season they 



