BRITISH GENERAL MIGRATORY MOVEMENTS 585 



our visitors for so long. The sportsman in autumn looks in favoured spots for the first 

 woodcock ; he welcomes it with a cartridge. 



IV. CLASSIFICATION OF BRITISH BIRDS ACCORDING TO 

 THEIR SEASONAL MOVEMENTS 



In the previous pages the known migratory movements of each species are described in 

 detail ; it is only necessary to summarise and review the general aspect of migration as affect- 

 ing the British area. For this purpose the following grouping will suffice: 



1. Resident Species. Birds which are present as species within the British area throughout 

 the year. Some of these are stationary, that is, the individuals which compose them do not 

 move outside the British area; they perform only local movements, which take them from the 

 nesting ground to some other locality within the British area : e.g. the red-grouse. Other species 

 are both stationary and migratory ; the species is always present, but may be represented to 

 a greater or less extent at various seasons by different individuals, owing to emigration and 

 immigration. A resident species may comprise, therefore, individuals that are stationary, 

 summer visitors, winter visitors, and birds of passage : e.g. the starling. 



2. Summer Visitors. Species which arrive in the British Islands in the spring to breed, 

 and normally depart again south in autumn : example, nightingale. Some of these species 

 include birds of passage which do not remain to breed, but visit us in spring and autumn on 

 their way to and from more northerly breeding areas : e.g. swallow. 



3. Winter Visitors. Species which arrive in the British Isles in autumn and remain until 

 the spring, when they depart to northern or eastern breeding quarters. Some of these also are 

 represented by birds of passage which visit us only for a short period on their way to and from 

 more southerly winter quarters : example, fieldfare. 



4. Birds of Passage. This term applies to individuals that pass our shores on their way 

 to their destination elsewhere. Many belong to species that are summer visitors, winter visitors, 

 or residents, but a number, which may be called passage species, are not represented by any 

 individuals which remain on our shores, except to rest and pass on : e.g. bluethroat. 



5. Irregular Visitors. Species which are in the habit of visiting the British Isles, some- 

 times in great numbers, at irregular but recurring intervals : example, sandgrouse. 



6. Accidental Visitors. Birds which do not normally travel along the British migration 

 routes, but have, for one reason or another, strayed accidentally into our area : example, 

 American bittern. 



V. RESIDENT SPECIES 



There are probably few, if any, of the stationary species which do not perform some local 

 movements. The red-grouse will at times leave the upper moors for lower ground, urged either 

 by the presence of food or driven from the uplands by severe weather and the consequent 

 absence of food. It may migrate to better feeding-ground in search of berries or young heather, 

 and these movements may become seasonal and regular. The meadow-pipit and twite, which 

 share the moorlands with the grouse, may journey no farther than the valleys in winter, or they 

 may travel for many miles to the coast. Many of the tits, often accompanied by one or two 

 creepers, regularly form flocks in winter, and wander in nomadic bands from food-base to 

 food-base. 



Several of our stationary forms differ more or less markedly from their continental con- 

 geners : the two races are entitled to subspecific rank. In some instances the British sub- 



