Colymbidæ.—On June 10th one great N. Diver seen swimming near Lighthouse, at Kyleakin, moving N. (but this movement may be due to set of the tide only, hour not given, J. A. H. B.). In autumn, at Sound of Mull, a G. N. D., passing S., var., light breezes. At Lismore, one flying south; stormy W., rain, on Oct. 17th. At Sound of Mull, two passing south, at noon; light airs. If the movement is only local and due to tides, this should be mentioned in schedules, and the words "drifting with tide," or "swimming with tide," used instead of "passing." They are not likely to swim against the tide, but if this phenomenon is observed it should be recorded. One species.
Weather Notes for General Remarks on Spring Migration, 1883.
Fearful snow-storm over the north of Shetland on March 17th, and N.E. gales and snow prevailed from March 5th to 24th; E. and N.E. and N. winds prevailed all over Scotland with gales, notably on March 6th and 17th; from 6th to 24th slight changes to S.E., but of short duration; on 25th (Sunday) wind S.W. strong to gale and rain, the first rain since February, but only lasted half a day; wind backed again to N.E. In Orkney the sea rose suddenly very high on the E. coast on March 21st; very cold and fine on 22nd, wind light S.W. "Large quantities of Cormorants, Razorbills, and Shags, &c., are coming ashore along the E. coast of Orkney. Deaths supposed to be from scarcity of food, viz., coal-fish; and great damage done to rabbits by Hawks, in some cases nearly exterminating them (daily papers of March 23rd, 1883). At Dunipace 12° of frost on night of March 27th. Fearful gale at 9 a.m. on March 30th, bar. at 28′ 9″; gale all night from S.W., bar. rising all day; again till 9 p.m. to 29′ 6″, wind S.W. at 10 p.m.; again at 30′ 2″. S. gale at Isle of May on March 29th and 30th.
As already mentioned in our General Remarks on 1882 Report (Fourth Report, 1882, p. 67) the effects of these gales and N.E. winds in spring of 1883 was almost to stop migration at Isle of May, which migration had "set in pretty briskly" on March 2nd, and almost ceased on the 5th. From the latter date only a few "stragglers of the strongest wings" up to the 19th; while a great concourse of Wagtails was observed inland in Edinburgh (see report as above quoted); few were seen at Isle of May till the 30th, when five came with S. gale (op. cit., p. 68).
The general migration was much weaker in numbers this season in spring, and this is doubtless owing to the prevalence of strong S.E. gales and winds at the time of migration, moderate S.E. or easterly winds being preferred. Still there were considerable rushes at the more favourable localities for observation especially of Thrushes and other Turdidæ.
The anomalous migration recorded by Mr. Cordeaux on to part of the English coast between Feb. 18th and May 18th,[29] with strong E. and S.E. winds, changing occasionally by N.E. to W. and N.W., is somewhat difficult of explanation, unless we could correlate data from the opposite coasts at the same dates in spring of 1883; but the fact stated by me that migration began briskly at Isle of May on March 2nd and almost ceased by the 5th may indicate that the migration thus retarded by adverse winds, or altered in direction thereby, passed N. by more inland routes, avoiding the Scottish coast-line, and hugging every sheltering hollow of land. Blown across the North Sea at the more southerly stations, they then crept northwards silently and more inland. Being all adult birds, and having crossed the North Sea not at the widest part if they came with a S.E. wind, less exhaustion would occur, and thus, passing inland, they would escape notice near the coast.
[29] See [p. 60] of this Report.
Before we can speak with much certainty as to the progress of spring migrations into the further districts influenced by them, we require more full and continuous data from Faroe and Iceland. Still, the earliest appearance noted in Iceland of the Redwing, Turdus iliacus, on April 7th, 1882, should be noted as a possible means of comparison in that year with the returns from our own coasts. Data from our West Coast of Scotland help us little in 1883 in spring, and even less so in 1882, as regards Turdidæ. Wheatears again, in 1882, are noted not before April 24th, and on West Coast of Scotland the migration, though but scantily observed, began on March 9th and terminated as late as May 17th (see 1882 Report, p. 57).
The autumn migration of 1883 was pronounced, and confined principally to end of October and November, of Turdidæ, Cinclidæ (one of which, seen at Isle of May, was afterwards described to me as having no brown between the black and white of the breast); also of Snow Buntings, Sky Larks, Robins (small numbers), Linnets, Chaffinches, Starlings, culminating in a grand rush past of the bulk between Oct. 28th or 30th and Nov. 3rd. The heaviest rush, observed at the time of a south wind, as compared with other years, at Isle of May, was on Oct. 13th and 14th, a S.E. wind, according to Mr. Agnew, being usually more favourable at that point. This October to November rush is undoubtedly the principal feature of our returns over the whole country. Of the expansion of the fan or wave our returns from both E. and W. coasts give a very fair indication. It seems likely that, although most land-stations have not returned very heavily-laden schedules,—not to compare, for instance, with 1882,—yet, as noticed by Mr. Cordeaux, quite as many, if not more, birds were observed at the light-ships; that the reason for this may be found in the normal and favourable direction of the winds prevailing in the North Sea at the time of autumn migration, resulting in greater numbers of birds passing inland without resting, and being thus less liable to come under observation, except at specially suitable stations. And, if we / compare the schedules of 1883 and those of 1882 on the West Coast of Scotland we find that, while larger numbers are recorded at the more northerly stations in 1883 than in 1882, there is a lighter return at more southerly stations in the autumn of 1883 than there was in the autumn of 1882. Thus to no inconsiderable degree the order of the statistics of two years is reversed. It would almost appear in this way that when a "spread fan" reaches our E. coast with S.E. winds—reaching, as it did in 1882, from Faroe S. to the English Channel—the birds, being tired and worn out, promptly seek shelter, and then, when rested, pursue their migration on more southerly lines, and do not reach so far west, except such as fail to catch up the land, and are driven forward helplessly. This would cause comparative desertion of the more northerly stations of the W. coast and Outer Hebrides, as in 1882. But on the other hand, when a "closed fan" reaches our E. coast with prevailing westerly and north-westerly winds, and, having much less expansion to the northward, as in 1883, as regards the E. coast, it seems that birds arriving, less exhausted with the winds best suited for their successful passage, pass on inland, the same lines of flight being persevered in, and thus reach further north upon the West Coast of Scotland.
Thus the Goldcrest, in 1883, reached as far north as Dhuheartach and Lismore in some numbers; but in 1882, when they came in such vast hordes to our east coast, we had no records north of Rhinns of Islay, and none others until we found them in "great numbers" at stations south of the Firth of Clyde.