AND THE OBSEEYATION' OF BIKDS. 61 



in one day over a parisli where, on the previous day, not one was 

 to be seen ; and the manner of their arrival is scarcely more re- 

 markable than the regularity with which they annually make their 

 appearance. 



The subject of migration, as I have elsewhere pointed out, is a 

 curious one, and the laws which govern it are yet imperfectly 

 understood ; but to advance here all that might be said in regard 

 to it would be beyond the limits of the present paper. It appears 

 highly probable from their constitution that most birds incline to 

 remarQ as much as possible in the same temferature throughout the 

 year, and hence their gradual movements north and south as they 

 feel the effects of heat and cold. If a sudden change comes, like a 

 sharp frost, we find birds lying dead under the hedges. This is 

 a proof of their sensitiveness. Some species, better able to endure 

 cold, but still averse to it, if they do not die, disappear suddenly, 

 and we are often surprised at the extraordinary scarcity of a species 

 one day which on the previous day was plentiful. I have always 

 attributed the cause to sudden change of weather. JVo doubt the 

 abundance or scarcity of food has some influence upon bii'ds in 

 their migration, but not to the same extent, I conceive, as change of 

 temperature. 



By wonderful instinct birds will follow cultivation, and make 

 themselves denizens of new regions. The crossbill has followed the 

 introduction of the apple into England. Glenco, in the Highlands 

 of Scotland, never knew the partridge till its farmers of late years 

 introduced corn into their lands ; nor did the sparrow appear in 

 Siberia until the Eussians had made arable the vast wastes of that 

 part of their dominions. 



For those who reside in the country, and have both taste and 

 leisure to observe the movements and habits of birds, I do not know 

 a more entertaining occupation than that of noting the earliest 

 arrival of the migratory species, the haunts which they select, and 

 the proportions in which they are distributed. 



In 1872, through the medium of the Natural History columns of 

 'The Field,' I distributed a number of copies of a 'Calendar of 

 Ornithology,' and invited the co-operation of naturalists in different 

 parts of the country in collecting and arranging statistics, from 

 which I hoped to derive some very interesting results. Eeferring 

 to the utilization of such observations, I remarked that upon 

 various points some addition to our knowledge seemed desirable. 

 Amongst other interesting facts, for example, might be ascertained 

 the precise line of dii'ection in which various species migrate ; the 

 causes which necessitate a divergence from this line ; the relative 

 proportions in which different species visit us ; the causes which 

 influence the abundance or scarcity of a species in particular locali- 

 ties ; the result of too great a preponderance of one species over 

 another, whether beneficial or otherwise to man as a cultivator of 

 the soil ; the simultaneity or otherwise of their departure from this 

 country in autumn ; the causes operating to retard such departure, 

 and so forth. All these are matters of interest, especially to those 



