VOL. VIII.] RELATIONS OF BIRD-DISTRIBUTION- 37 



attachment of species is x^i'edominantly due to divergent 

 racial environmental history. The species is essentially 

 adapted, not to its present, but to the ancestral 

 environment — an adaptation '\\-itli which is correlated an 

 inherited mental bias ^\'llich attaches the species to the 

 nearest present representative of such racial environment. 

 And since the food-supply is but one unit of the complex 

 to which the species is adapted, such food-supply tends 

 to be sought only within the limits of that complex — 

 which tendency is most pronounced during the breedirig- 

 season. To take a theoretic examiDle. If the requisite 

 food-supply of the Golden Plover exists alike in moor 

 and arable groimd, then the Golden Plover, in its 

 restriction to moors during tlie nesting-season, illustrates 

 the difficulty \\-ith ^\-hich a species extends its breeding - 

 range beyond its hereditary environment where a suitable 

 food-supply exists outside such limits. Tiiough food- 

 supply is the basis essential, its subjective attachment to 

 other environmental relations tends to prevent distri- 

 butional range from being co -extensive (in environmental 

 type) with the food-supply. Thus the comparative 

 restriction of the Golden Plover to moors, of the Gold- 

 crest to coniferous woods, of the Curlew to the uplands, 

 is not necessarily due to a coincident restriction of 

 food-supply. 



Whatever the origin of the connexion, and whatever the 

 present links, the close relation between vegetation -type and 

 bird -distribution is clear ; and in practice it appears that 

 the plant-formation and plant-association of the botanist, in 

 degree as they are contrasted in character, show proportionate 

 contrast in their associated avifauna — which parellelism is 

 an index to the intimacy of the connexion. Woodland 

 avifaimas are more distinct from those of moorland than that 

 of birch-wood is from that of pine-wood, or than that of 

 heather-moor from that of cottongrass moor. The former 

 are distinct in class ; the latter, generically alike. 



If the subject is ajDproached from this aspect, and the 

 question asked, not how birds are distributed, but what 

 species are supi^orted by the specific environment, there arises 

 the preliminary question as to the relative faunal value of 

 nesting and non -breeding birds. It has been argued that the 

 home of a migrant is essentially that country which gave it 

 birth, and in \\hich it breeds ; that a bird is only British when 

 it is literally native or indigenous. To non-ornithologists 

 this might appear a truism — yet it is not the accepted basis 

 of classification. If it has its objections, it has on the other 



