286 iiEPOKT— 1882. 



or pai'tly to both. It would, we think, assist in proving oi' disproving 

 theories of land-communication which have been advanced and disputed 

 by previous writers. At present we cannot positively state from our 

 present data whether an actual or only an apparent preponderance of birds 

 pass south of the Tweed in autumn. It appears, however, a little curious 

 to find a highway of migration by the Pentland Firth so much further 

 north than the stations mentioned. Writing from North Ronaldshay, 

 Orkney, Mr. Tnlloch remarks upon the usual scarcity there, and says 

 ' they keep more direct for the mainland ; ' and he remarks also upon the 

 abundance of birds seen in September and November at Pentland Skerries, 

 where he was light- keeper for four years. He remarks especially on the 

 number of ' Mountain ' Thrushes, Blackbirds, Owls, Woodcocks, Wrens, 

 Robins, and Titmice which occur there whein the wind is from the east, 

 from which station there is a large numerical return this year. The isolated 

 position of the lights at Pentland Skerries, Caithness, combined with the 

 local prevalence of easterly winds, is perhaps sufficient to account for the 

 large mass of the records. At all events, the returns from this station 

 deserve special attention and study. 



With a dry hot summer in Northern Europe, migration is always 

 earlier than in years of rain and low temperature, birds breeding sooner 

 in the former, and the nestlings, like all other young things, with dry 

 weather and sunshine developing more rapidly. Nothing is more re- 

 markable in the phenomena of migration than the punctuality with which 

 certain species return in the autumn, one species regularly taking prece- 

 dence of another, also in respect to the date of the arrival year after year. 

 In the Limicolce and Anatidce the date of the autumn migration varies 

 often considerably from year to year ; but with some species — as the 

 Wheatear, Redstart, Fieldfare, Redwing, Hooded- Crow, Goldcrest, Wood- 

 cock, and others — we may almost predict to a day the time of their first 

 appearance. 



The Period of the migration flight in the autumn of any particular 

 genus or species is most probably referable to two causes : the first — one 

 of temperature— affecting the time of nesting ; the second is the period at 

 which the young arrive at maturity, or rather that period when they 

 throw oS" parental control or are thrown off themselves. 



When able to act independently and procure food on their own account, 

 they flock together and migrate in a body. We know that, with rare 

 exceptions, the young of the year migrate some weeks in advance of the 

 parent birds. Thus we can readily conceive the whole of the large raptorial 

 birds nesting about the same time over widely extending districts in 

 Northern Europe ; when all the many young arrive at this self-dependent 

 stage there would be a simultaneous movement ending in a universal 

 migratory rush. This period of self-dependence is arrived at much more 

 quickly in some birds than in others, for species like the Knot, Grey Plover, 

 Godwit, and Sanderling, nesting in very high latitudes, leave our shores 

 the last in the spring of any of the migrants, and their young are amongst 

 the first to return in autumn. The order of migration, more especially in 

 connection with the shore birds, is the occurrence very early in autumn 

 — July or August — of a few old birds in summer plumage, either barren, 

 or such, perhaps, as have been prevented nesting, then the young in large 

 flocks, and, some weeks subsequently, old birds. 



The observations taken at the various stations, both on light-vessels 

 and from lighthouses, show a marked improvement on those of previous 



