NOTES AND QUERIES. 235 



branch quite violently. Such behaviour in this species is not usual. 



E. P. BlJTTERFIELD. 



Further Notes on Newton's Statements on Birds. — I am some- 

 what interested in Mr. E. P. Butterfield's remarks (' Zool.,' 1916, 

 p. 196). There can be no doubt of quite considerable differences 

 between the observations of field-naturalists made during recent 

 years and those made even a very few years ago. And, with equal 

 certainty, the changes observed, as regards distribution and dispersal, 

 become more and more marked in the course of one man's life, and 

 of the time he may have devoted to the observing of such pheno- 

 mena. But whilst these very marked differences scarcely warrant 

 critical remarks regarding the accuracy of previous recorders, they 

 often do add very considerably to the current interest of the studies 

 in Ornithology, as they also do in most studies of other branches 

 of natural history inquiry. 



Distribution and dispersal, extension or compression, increase or 

 decrease, development or contraction are all subjects — it is almost 

 needless to insist — which are intimately connected ; and most surely 

 have a distinct bearing as a whole upon other phenomena, such as 

 migration, food-supplies, changes in temperature, character of the 

 seasons year by year, and even in the habits of species. These act 

 and interact in their courses, and become more and more differen- 

 tiated the longer the time of careful records is extended. But the 

 results regarding the past and present periods in the life-history of a 

 species must be limited to absolute knowledge and records in the 

 past, and the ability and continuous day-by-day, month-by-month, 

 year-by-year observing and recording in the present, of students of 

 these subjects. Yet the whole lifetime of one observer, however 

 capable and however devoted, is quite insufficient to enable him to 

 arrive at finality. To attempt prophesying a future expansion or 

 restriction may require the whole lifetime of a whole generation of 

 accurate recorders — even in some single quite limited area — at least 

 as regards many or most of our very commonest species. And if the 

 larger areas be considered, how vastly greater must be the numbers 

 of accurate observers and recorders required to arrive at any finality ! 

 These recorders must be situated in all parts of the world, occupying 

 every conceivable kind of locality, and their records kept with strictest 

 continuity. Even then perfection could scarcely be arrived at, or 

 prophecy ever approach it. And, after all, these are the very points 

 which add to the interest of study — something gained, but much 



