BRITISH BIRDS NUMBER 3, VOL. XLV, MARCH, 1952.

VISIBLE MIGRATION AT LAND'S END. BY DAVID AND ELIZABETH LACK (Edward Grey Institute, Oxford) INTRODUCTION THE study of visible migration, initiated by Eagle Clarke (1912), has received a new impetus in the last few years. In October, many Sky-Larks (Alauda arvensis), Chaffinches (Fringilla caslebs) and Starlings (Sturnus vulgaris), with smaller numbers of other passerine species, migrate by day southwest and west across England and have been traced as far as North Devon, where the coasting movements westwards have attracted much attention (Allen, 1944, Bannerman, 1944; Holt, 1950; Hurrell, 1944; Lack, 1949; Simms, 1950 ; Wood, 1950). To see what becomes of these birds, we spent from October 8th to November 1st, 1951, in the Land's End region. Here we watched chiefly at Gwennap Head, the south-western "corner" of England, and at Cam Gloose and Cape Cornwall, adjacent headlands half-way up the west side of the Land's End peninsula, also paying occasional visits to other places. The main localities are shown in Fig. 1. The only previous observations on migration in this area are at Cam Gloose by Hartley (1945), who saw Sky-Larks coasting south on many days in October, and Chaffinches once going south and once north. Particularly where birds are taking off over the sea, it helps to have two observers, one counting all that passes and the other following selected parties as far as possible to determine their direction of flight, which sometimes changes out to sea. Actual counts are important, as they enable quantitative comparisons to be made, and they should extend over at least one hour continuously, preferably for longer. Counts over sample periods of five minutes, as by Holt (1950), are in our view highly misleading. The places selected for observation may be critical. To give only one example, on October 10th one of us, on the tip of Gwennap Head, saw Sky- Larks mainly taking off south out to sea, while the other, only two hundred yards further east, saw chiefly birds travelling east along the coast. This was because Sky-Larks coming from the north divided into a southerly and an easterly stream several hundred yards before they reached the southern cliffs. One observer alone would have had a misleading idea of what was happening. Most of the migration that we saw was of birds " coasting," i.e. travelling along the coast and following all the major turns and bends, though sometimes cutting across the top of a projecting headland or over a small bay. In most cases the birds travelled on a narrow belt slightly inland of the cliffs. We also saw birds taking off out to sea, nearly always coming from the coasting stream, except 82 BRITISH BIRDS. [VOL. XLV.

in the case of the Starling, in which the flocks usually appeared from inland. At Cam Gloose and Cape Cornwall, near which we resided, we started our observations soon after dawn, but at other localities not until about 08.15 hours (sun-time). We normally ceased watching about noon, but on some days resumed again in the after­ noon. NUMBERS IN RELATION TO WEATHER AND TIME OF DAY In Table 1, we have set out the number of individuals passing in the peak hour of each day under different weather conditions. This shows that much more migration took place with a light than with a strong wind, and in sunny weather than in either fog or rain. A strong wind had a much greater adverse effect on the Chaffinch than on the Sky-Lark, but Chaffinches seemed less affected by rain than Sky-Larks. Scarcely any migration was seen in heavy rain with a strong wind, or in fog, or on one day when it was heavily overcast due to high fog. Sky-Larks started passing soon after sunrise, reaching their maximum between 08.00 and 10.00 hours, in the second and third hours after dawn, with no sharp peak. Migration usually continued in moderate strength until about noon, and occasional parties passed during the afternoon. Chaffinches also started passing soon after dawn, usually reaching a sharp peak about an hour later, while on most days the movement was almost over by 10.00 hours. There were, however, exceptions. On October 25th, after a fine early morning, the wind freshened and the sky became overcast, and a big movement started at 10.45, reaching a peak around 11.00 (when 400 birds passed in 15 minutes) and continuing, with intermissions, until 12.30, with occasional parties until at least 13.40 hours. On October 30th, on the other hand, the biggest movements occurred at dawn, but these were of birds setting out over the sea, not coasting, while on November 1st a big coasting movement was well under way as early as 08.00 hours, when we had to leave. In the Starling, all the big departures out to sea took place around dawn, but flocks of smaller size continued to leave in the next two hours, and we saw one party of 150 birds set out at 15.45 hours. Sky-Larks usually travelled in parties of under 10 birds, and flocks of over 25 were uncommon. Chaffinches were chiefly in parties of 10 to 25, except when the movement slackened, when most parties included less than 10 individuals, while in the biggest movements flocks of 30 to 80, and once 120, occurred. The Starlings migrating at dawn were often in flocks of over 1,000 and one huge flock must have included 5-10,000 birds. After the dawn departures were over, the departing flocks usually included between 50 and about 400 birds. HEIGHT OF FLIGHT Coasting Sky-Larks usually flew 50-100 feet above the ground, but when coming from the cliffs over the sea, they would fly a little way VOL. XLV.] VISIBLE MIGRATION AT LAND'S END. 83 and then characteristically drop down low over the water, proceeding at this height until out of sight. Coasting Chaffinches usually flew rather higher than Sky-Larks, though so long as we stood on the highest part of the cliffs, none were so high as to be difficult to see. On the few occasions when Chaffinches went out over the sea, they called more frequently than usual and rose higher. This happened even when the birds eventually returned to the land. Parties breaking off out to sea from coasting movements on October 25th and 30th remained at moderate height, but others setting off direct from a roost on October 30th circled up until they were almost at the limit of vision before heading out to sea, and one party rose beyond our range of vision before leaving the coast. Starlings usually flew low over the ground from inland on a broad front in a long straggly line, but on going out over the sea they bunched together and rose somewhat, though not nearly so high as Chaffinches. BEHAVIOUR WHEN SETTING OFF In normal weather soon after dawn, and in foggy weather when the sun broke through later in the morning, we often saw Sky-Larks starting to migrate from stubble fields. The birds would rise up, calling, then settle again. One party would set off, others rising with it but turning and again pitching. Then nearly all the birds might rise from one field, fly perhaps 100 yards and settle in another field, often returning again a few minutes later. Sometimes a large flock would rise together and set off, but a small group would detach itself and return. At these times, the birds acted rather excitedly, calling frequently, as during the migration itself, and flying in a variety of directions. We saw this behaviour both when birds were setting off along the coast and also at the Lizard Point, where many were taking off directly from the fields out to sea. Many Chaffinches, evidently on passage, roosted in bushes inland near Cape Cornwall. Soon after dawn these birds behaved similarly to the Sky-Larks described above, rising in small parties and settling again, making random flights from the bushes to the fields and back again, and calling frequently. Before setting off, they sometimes circled to gain height, and this was particularly the case on the day when they set off directly out to sea. The first flocks of Starlings would appear from inland at dawn and sweep straight out to sea, presumably having come direct from roosts near the coast. Others often went straight out in this way later in the morning. Many flocks, however, would come down to the shore, or to fields near the shore, and settle. Here they usually kept in closely bunched flocks, chattering vociferously, apparently feeding, running rapidly over the ground, and at intervals rising, flying a short distance and again settling. At intervals, a party would detach itself and take off over the sea, some of the birds perhaps turning back when off-shore, or the whole flock might rise up, circle and leave. Despite their excited chattering on the ground, the migrating parties were completely silent, this being in marked 84. BRITISH BIRDS. [VOL. XLV. contrast to migrating Sky-Larks and Chaffinches, which call repeatedly. MOVEMENTS OF SKY-LAKK Sky-Larks were migrating nearly every day during our stay from October 8th to November ist. Their movements were complex, and we took time to unravel the story, which is based on repeated visits to the Cape Cornwall area and to Gwennap Head, but on only one to three visits to Hudde Down, Navax Point, Pendeen Watch, Carn-Du, Kynance Cove and the Lizard, at all of which further observations are needed. The reader should follow the ensuing account with the help of Figs, i and 2.

FIG. 1. MAIN LOCALITIES VISITED.

The subsequent movements of the Sky-Larks coasting west and south-west down the north coast of Devon and Cornwall are shown in Fig. 2a. At Hudde Down we picked up the birds coasting west, and saw them briefly turning northwest with the coast at Navax Point, but cutting west over the top of the headland. At Pendeen Watch Sky-Larks arrived from the east, cut over the neck of the headland and followed the coast on south-west, and at Cape Cornwall they turned south with the coast, usually cutting over the neck of the headland, then keeping on south past Carn Gloose. At Gwennap Head, on the " corner," where the coast turns sharply from south to east, the coasting birds did likewise and travelled on east. At Carn-Du, where the coast turns north into Mount's Bay, we saw VOL. XLV.] VISIBLE MIGRATION AT LAND'S END 85

FIG. 2a. SUBSEQUENT MOVEMENTS FIG. 2b. SUBSEQUENT MOVEMENTS OF SKY-LARKS COASTING SOUTH­ OF SKY-LARKS COASTING WEST WEST DOWN NORTH COAST. ALONG SOUTH COAST.

FIG. 2C. KUCKZUG OF SKY-LARKS IN FROM THE SEA. two parties of Sky-Larks, one a large one, leave the coast and strike out E.N.E. over the bay. At Kynance Cove, on the Lizard peninsula, birds were heading south-east along the coast towards the Lizard Point, where we saw them turning east with the coast. We have not followed them further. Summarizing, the stream of Sky-Larks coasting down the north coast continues right round the Land's End peninsula, travelling first west, then south, then east, following every local turn of the coast between north-west and E.N.E., though we did not see them turn further north than E.N.E. From this coasting stream, parties detached themselves at inter­ vals and took off in two different directions, one group W.N.W., in the direction of Ireland, and the other group south, in the direction of Spain. Taking the latter movement first, as we saw much more of it, many of those coming down to Gwennap Head from the north proceeded straight on out south. We followed many parties to the limit of visibility. Some turned when a little way off-shore and rejoined those coasting east, but most kept straight on. Of those which coasted east, many turned and went out south at Hella Point, a headland a few hundred yards east of Gwennap Head, while 86 BRITISH BIRDS [VOL. XLV.

the rest continued on east. This coasting stream eventually reaches the Lizard Point, where we saw many others take off south out to sea, while the rest continued coasting east. The existence of a southward passage from further east was demonstrated by Clarke (1912), who saw parties of Sky-Larks heading south on October mornings, during his stay at the Eddystone Lighthouse.

FIG. 3. AUTUMN MOVEMENTS OF SKY-LARK IN W. EUROPE. Fig. 3 shows that if these birds continue south, they will strike land in north Spain, 400 miles away. Goodbody (1950) likewise saw Sky-Larks heading south from south-east Ireland, and these birds would have to travel 600 miles before reaching land. Goodbody points out that a small deviation to the east would bring them to Cornwall, but we did not see birds arriving from Ireland in this way. Further, the existence of a southerly passage over the Bay of Biscay is confirmed by our observations in October, 1949 and 1950, at Hendaye, on the Franco-Spanish frontier, and at St. Jean de Luz. Here we saw large flocks of Sky-Larks arriving in off the sea, flying south, presumably having crossed the Bay of Biscay, but starting VOL. XLV.] VISIBLE MIGRATION AT LAND'S END. 87 from further east than the longitude of Cornwall. On reaching the coast, these birds proceeded straight on south inland, and we saw them later passing high over a 3,000 foot mountain, 'fait (1924) observed large movements of Sky-Larks in October south down the Portuguese coast, and as the birds arriving in the Hendaye region did not coast west, those seen by Tait presumably crossed the Bay of Biscay further west. They may well be the birds from Ireland. The evidence therefore suggests that Sky-Larks cross the Bay of Biscay southwards on a broad front, setting off from various English and Irish headlands. The flight from Ireland to Spain is of similar length to that over the Gulf of Mexico, which Lowery (1946) has shown is regularly undertaken by passerine birds. It came as a surprise when we first saw a party of Sky-Larks coasting south near Cam Gloose break away and set off out to sea W.N.W. We had not considered the possibility of the coasting stream including birds bound for two different destinations, nor had we thought that birds eventually travelling rather north of west towards Ireland would temporarily coast due south. Later we saw several other parties take off from near Cam Gloose in this way, also one party from Pendeen Watch. Several other parties even followed the coast as far south as Gwennap Head, and there took off over the sea, first south, then turning south-west, then west and eventually north-west ! Occasionally, also, flocks came down to Gwennap Head from the north, reached the southern cliffs and then turned back north, presumably taking off W.N.W. from further up the coast. This is not yet the full story, for we found another coasting movement of Sky-Larks, west along the south coast of Cornwall, the subsequent movements of which are shown in Fig. 2b. These birds arrived at Gwennap Head from the east, where many of them struck out W.N.W. over the sea in the direction of Ireland, while others turned and coasted north. We traced the latter to Land's End, where we saw many more taking off W.N.W., while others continued coasting north. Likewise at Cam Gloose and Cape Cornwall, other parties took off W.N.W. and the rest continued coasting north. At Pendeen Watch, where the coast turns east, we saw two parties of Sky-Larks continue out north or N.N.E. over the sea away from the land, perhaps bound for West Wales. Further observations are needed here. One might expect that birds destined for Ireland would be reluctant to coast east, though in a strong wind Chaffinches did so on one occasion (see later). The Sky-Larks heading for Ireland left between north-west and just north of west, most of them about W.N.W. Fig. 3 shows that this would bring them to south-west, not south-east, Ireland. Ruttledge (1938) recorded a large passage of Sky-Larks north up the west side of Ireland in October, these perhaps being the birds that we saw taking off for south-west Ireland, which later turn north up the west coast, and presumably from there spread graduallv 88 BRITISH BIRDS. [VOL. XLV. inland to their wintering grounds*. On our one visit to the Lizard, the wind was south-east and hence unfavourable for Sky-Larks coasting west (see later). We did, however, see one party arrive from the east, make two attempts to take off out to sea south and then continue on west. Further, two Pied Wagtails (Motacilla alba) came coasting west and then took off south-west out to sea. Also, at Carn-Du we saw a party oi Sky-Larks arrive from the east and then strike out to sea due south. These observations suggest that the birds coasting west along the south coast, like those coasting west along the north coast, included not only individuals heading for Ireland but others heading for Spain. We have therefore shown arrows southward in Fig. 2b, but the regularity of such movements needs confirmation. It may be suggested that the Sky-Larks passing through the Land's End region and then proceeding westwards towards Ireland have come chiefly from Central Europe, and are those seen by Eagle Clarke (1912) crossing the North Sea due west, while those passing through the Land's End region and heading south towards Spain have come chief!}' from Scandinavia, and are those reported by Clarke arriving on the northern coasts of Britain from the north-east. Fig. 3 shows the geographical relations of these various movements. We saw one further movement in the Land's End area, of Sky- Larks coming in from the sea, the direction of flight usually being north-east at Gwennap Head, east at Cape Cornwall and south­ east at Pendeen Watch, i.e., at right angles to the coast, as shown in Fig. 2c. On arriving at the coast, these birds normally went straight on inland, and they often pitched if they reached fields suitable for feeding. We conclude that this was a " Ruckzug " of birds which started to cross the sea but turned back and headed for the nearest coast. As a result of these various movements, we were sometimes able on the same day to see Sky-Larks migrating in appreciable numbers in five different directions at Gwennap Head! Those coming from the north (i) went out south or (ii) coasted east; those coming from the east (iii) went out W.N.W. or (iv) coasted north ; and there was (v) a Ruckzug in from the sea north-east. All those setting off south towards Spain arrived from the north, and nearly (but not quite) all those setting off W.N.W. towards Ireland arrived from the east. It may be suggested that this is because nearly all those coasting west and south along the north coast which are destined for Ireland have already taken off over the sea before getting as far south as Gwennap Head ; likewise those coasting west along the south coast and destined for Spain have similarly taken off before getting so far west. A glance at Fig. 3 will show why this should be so. The numbers that we counted coming from each direction to Gwennap Head are shown in Table 2 for the peak hour each day. *I. M. Goodbody writes that recent observations by the Irish Ornithologists' Club have revealed a strong north-westerly movement of Sky-Larks arriving on the east coast of Ireland from the direction of England. VOL. XLV.] VISIBLE MIGRATION AT LAND'S END. 89

During our visit as a whole, the total arriving from the north was rather similar to the total arriving from the east, but on any particu­ lar day one or the other group tended to predominate greatly, the coasting passage being stronger against the wind. Thus with a south-east wind, the birds coasting south then east predominated, while with a northerly wind the birds coasting west then north predominated. This was corroborated at Cape Cornwall, where the coast runs north and south. Here we watched on eight days, on six of which the wind was between south and east and the coasting movement was almost exclusively southwards, and on two of which the wind was northerly and the coasting movement was almost exclusively northwards. The birds arriving at Gwennap Head from either direction split up into two groups, those continuing on out over the sea and those turning along the coast. As this division often took place a short distance before the birds reached the cliffs, it was not possible to count both groups accurately from the same place. In Table 2, therefore, we have given only a general indication of which movement was the stronger (see note ii for the terms used). If the directions taken by the birds are compared with the wind directions, it will be seen that Sky-Larks tended to set out over the sea chiefly with a following wind, or when to turn along the coast would have given them a following wind. Conversely, they tended to turn and follow the coast when this brought them, head on to the wind, or when the sea crossing would have been against the wind. In addition, more set off out to sea in sunny weather with a light wind, than in fog or with a strong wind. Hence the coasting movements of the Sky-Lark occurred chiefly when conditions were less favourable for migration, and in particular with an adverse wind. Further, big movements of Sky-Larks, perhaps the main ones, occur at night (Clarke 1912). Perhaps, therefore, the coasting movements, which are the main phenomenon seen by the field observer, are only a small and unimportant part of the migration of the species. MOVEMENTS OF CHAFFINCH Chaffinches were migrating on all suitable days from October 13th to November 1st, but not between October 8th and 13th, although two days (9th and 10th) seemed suitable. The movements of the Chaffinch were similar to those of the Sky-Lark but less complex, and we have therefore shown all of them on one map, Fig. 4. The birds travelling west along the north Cornish coast were seen at Hudde Down going west, at Cape Cornwall and Cam Gloose going south, and at Gwennap Head going south, then turning sharply east with the coast, while at Carn-Du two Chaffinches coasting east there left the coast and struck out over Mount's Bay E.N.E. The route round the Land's End peninsula was therefore the same as that taken by coasting Sky-Larks. As in the Sky-Lark, also, there was a coasting movement in the opposite direction, the birds travelling 90 BRITISH BIRDS. [vol.. xi v.

FIG. 4. MOVEMENTS OF CHAFFINCHES, BOTH THOSE COASTING FROM NORTH COAST AND THOSE COASTING FROM SOUTH COAST. west along the south coast and turning north at Gwennap Head, and continuing north past Cam Gloose and Cape Cornwall. Further north at Pendeen Watch, one party left the coast and struck out N.N.W. over the sea, a route also taken by Sky-Larks and Starlings, but many other parties turned and followed the coast east, and temporarily even south-east. This was with a strong south-east wind, but even so it was a remarkable direction to be taken by birds presumably destined for Ireland. Coasting Chaffinches took off over the sea far less often than Sky- Larks. On October 25th, with an east wind, there was an unusually heavy passage south past Cam Gloose, and three parties, involving over 150 birds, broke away and went out W.N.W., being followed a long way without changing direction. Even on this day, however, most parties kept on south, though several cut south-west across Whitesands Bay towards Land's End, a sea crossing of 3 to 4 miles, which we did not see them undertake on other days. The only other day that we saw Chaffinches taking off in the direction of Ireland was October 30th, after a hold-up due to bad weather. In still fine weather just after dawn, three parties, involving at least 120 birds, circled up from roosting places near Cape Cornwall and went straight out to sea between W.N.W. and north-west. A little later, near Cam Gloose, small flocks of Chaffinches appeared from the south coasting north, and most of these set off out to sea between W.N.W. and N.N.W., in all ten parties totalling 72 birds leaving between 08.20 and 10.35, while three parties totalling 20 birds continued coasting north, and two individuals coasted south. In similar weather at dawn on November 1st, many parties started by circling up, but all then coasted south; none went out to sea. We apparently saw many fewer Chaffinches migrating than have been reported coasting west in north Devon. Should this conclu­ sion be confirmed in other seasons, it may be suggested that many of these coasting west in Devon are destined for Ireland and have already taken off over the sea before getting so far south as Cape Cornwall. We saw no Chaffinches take off south over the sea. On fine days VOL. XLV.j VISIBLE-MIGRATION AT LAND'S END 91 with a light wind, many of the parties coasting south to Gwennap Head rose high on reaching the cliffs, and went some way out to sea, but all eventually turned back and coasted east, though some did not turn until well off shore. The Chaffinches coasting south and then east in this way presumably cross the Channel later, probably at night, as found by Clarke (1912) at the Eddystone. As, however, Chaffinches crossing the sea by day sometimes do so at a great height, it is possible that a diurnal passage over the Channel has been overlooked. On any one day, the coasting movement of Chaffinches was wholly or almost wholly in the same direction, though a very few individuals occasionally flew in the opposite direction for at least a short way. The data for Cape Cornwall and Gwennap Head in Table 3 show that the coasting movement was nearly always against the wind. With an east or south-east wind the birds coasted south, turning east at Gwennap Head, and with a northerly wind they coasted north, having turned from the west at Gwennap Head. To this there was one exception, since on October 19th with a light north­ east wind, all the birds coasted south then east. Table 3 also shows that the movement south from the north coast was much larger in size than that north from the south coast. The maximum passage northwards, in very favourable weather, was 75 in the hour, the maximum passage southwards was ten times this figure. On October 26th, with a strong south-east wind, Chaffinches were coasting south at Cam Gloose, but at Pendeen Watch, only four miles to the north, the movement was north-east up the coast, then south-east round the headland and on east. 120 passed in this way in an hour. Further observations are needed to interpret this. Chaffinches on passage roosted each evening in large numbers a little inland of Cape Cornwall, and we often saw a coasting migration start from here. On this day, the birds evidently left in two direc­ tions from these roosts. As Chaffinches cross the sea mainly at night, or in high flights by day, it is more obvious than in the case of the Sky-Lark that the coasting movements seen by the observer are an unimportant frac­ tion of the migration of the species. MOVEMENTS OF STARLING We saw the first Starlings migrating out to sea on October 14th and small parties left on most of the following days, but the passage was not large until October 25th, and much the largest flocks were seen on October 30th and November 1st, our last days. The move­ ments of the Starling, set out in Fig. 5, were much simpler than those of the other species, as there was little coasting. We saw most departures from the west coast, between Land's End and Cape Cornwall. Big flocks came from inland about dawn and went straight out to sea W.N.W. or north-west towards Ireland. Later in the morning, smaller flocks came down to the coast, some of them flying straight out, others turning and coasting (usually 92 BRITISH BIRDS. [VOL. XLV.

FIG. 5. MOVEMENTS OF STARLING. north) for a short way, others settling temporarily and then either taking off over the sea or moving further along the coast. The coast­ ing movements were rather indefinite and were not easy to dis­ tinguish from feeding movements of resident flocks. On October 30th, a peak day at Cape Cornwall, one party of 5-10,000 birds left out to sea at 07.25, another flock of 1,000 at 07.40, while between 07.40 and 07.45 three more flocks, each of several hundred birds, came from inland and turned north up the coast. Between 08.20 and 09.20, another 15 parties came from inland down to the coast and turned north, 500 in one flock near the beginning and later parties of 25 to 120 birds, once 300, in all 1,800 birds. Another 500, in six flocks, passed in the next half-hour, but the movement then fell off markedly. Likewise on November 1st at Cape Cornwall, a flock of about 3,000 left out to sea at 07.20, and in the next 40 minutes 11 more parties, totalling some 1,600 birds, came down to the sea from inland, all in this case leaving out to sea about north-west, though two parties coasted a short way south before doing so. At Gwennap Head, the Starling movement was on a smaller scale than at Cape Cornwall. Thus between 08.40 and 09.40 on October 30th, when 13 parties involving about 1,000 birds passed at Cape Cornwall, only seven parties involving 166 birds passed at Gwennap Head. This difference is probably due to the fact that the Starlings mostly fly W.N.W. or north-west from inland, hence few would reach Gwennap Head, in the south-west corner of the peninsula, except those travelling along the south coast. • Combining our observations for all days at Gwennap Head, we saw ten parties arriving from the east along the coast, five of which set off out to sea W.N.W. or north-west while the others turned north up the coast. In addition, we saw two parties of 50 birds come coasting down from the north, join up, and set out south over the sea. They were followed a long way, and did not change direction, so were presumably bound for Spain. This was on October 17th. Three days earlier another small party headed south out to sea, but then turned and coasted VOL. XLV.] VISIBLE MIGRATION AT LAND'S END. 93 east. Clarke (1912) recorded a southerly passage at the Eddystone but only at night. At Pendeen Watch, where we saw one flock of Starlings take off in the normal direction just west of north-west, in the direction of Ireland, two others (on different days) set out N.N.E. and N.N.W. respectively, presumably making for west Wales or eastern Ireland. More observations are needed here. Starlings, like Sky-Larks, were also seen coming in from the sea at right angles to the coast, north-east or east at Gwennap Head, east at Cape Cornwall, and E.S.E. or south-east at Pendeen Watch. The numbers involved were far smaller than of those setting out, the flocks usually consisting of under 50, often under 10, individuals. Once, however, soon after dawn, about 1,000 birds came in from the sea together, in a straggling front extending for about half a mile. These birds appeared 15 minutes after a flock of some 3,000 had set off, at a time when the coast was clear but there was mizzling rain out at sea. We sometimes saw part of a sea-going party break off and return to land, and others presumably did so further off shore. The returning parties often alighted in the fields. This Ruckzug was exactly comparable with that seen in the Sky-Lark. OTHER MIGRATING SPECIES Five other small passerine species were seen travelling along the coast occasionally, but it was difficult to be sure whether they were migrating, or merely local residents. These were the Goldfinch {Carduelis carduelis) and Linnet (C. cannabina) in flocks of six to 30 birds, the Meadow-Pipit (Anthus pratensis) in parties of seven or under, chiefly in the first half of our stay, the Pied Wagtail (Motacilla alba yarrellii), usually travelling singly, in twos or threes, and the Reed-Bunting (Emberiza schceniclus), of which one and then two were seen on October 23rd. Some of these coasting parties were almost certainly migrating, as we saw others taking off out to sea, as follows: Goldfinch, 25 out south-east from the Lizard on October 10th, and five possibly out W.N.W. from Gwennap Head on October 17th ; Linnet, parties of four, 14, 20 and 30 out south-west from Gwennap Head on October 14th, and parties of six and nine out south-west and a party of ten out W.N.W. from Gwennap Head on October 17th ; Meadow-Pipit, small parties out south, sometimes with Sky-Larks, from Gwennap Head on several days in the first half of our stay, the maximum being 17 birds in one morning; Pied Wagtail, two coasting west which then took off south-west, from the Lizard Point on October 10th, and three out W.N.W. from Gwennap Head on October 17th. These four species, like Sky-Larks, dropped low down over the water when setting off seaward. We also saw small parties of Swallows (Hirundo riistica) and House- Martins (Delichon urbica), the largest flock consisting of nine birds, usually coasting against the wind, and once drifting southwards out to sea from Gwennap Head. A late Swift (Apus apus) coasted south past Cape Cornwall on October 13th. 94 BRITISH BIRDS. [VOL. XLV.

At 10.15 a.m. on October 23rd, a Heron (Ardea cinerea) set off south over the sea from Gwennap Head, circling, flapping and gliding at a moderate height above the water, until lost to sight a long way out. Clarke (1912) recorded this species passing south at the Eddystone at night. Finally at 10.35 a-m- on October 15th, we saw a Buzzard (Buteo buteo) set off S.S.E. from Carn-Du, disappearing into mist when some distance off shore, so we cannot be sure that it was migrating. We also saw a number of uncommon passage migrants along the cliffs, including a Snow-Bunting (Plectrofihenax nivalis), a Richard's Pipit (Anthus richardi), several Ring-Ousels (Turdus torquatus), several Black Redstarts (Phoenicurus ochrunts), a Short-eared Owl {Asio flammeus), several Merlin (Falco ccsalon), and a Pink-footed Goose (Anser fabalis brachyrhynchus). Further, both Fieldfare (Turdus pilaris) and Redwing (7". musicus) appeared on the cliffs several days earlier than we saw any inland. These records are of no special interest, except in suggesting that the coastal route is used by other, including nocturnal, migrants, and details will appear in the Annual Report of the Cornwall Bird Watching and Preservation Society. GAPS IN OUR KNOWLEDGE We would stress that we watched regularly only round Gwennap Head and Cape Cornwall (with Cam Gloose). The arrows on our maps for other places are based on very few observations, and movements almost certainly occur there in directions additional to those observed. Pendeen Watch, Carn-Du and the Lizard would particularly repay further study, as would many localities further east. We have, however, carried the problem a stage further, and hope that this paper will stimulate others to take part in the exciting sport of migration-watching. There are large areas of coast and many inland localities concerning which nothing is yet known, and where the pastime might be pursued with both profit and enjoy­ ment. We would stress, too, that the biggest gap of all may be the migrations that we cannot see, because they occur either at night or at too high an altitude by day. Visible migration may, in fact, be only a small and unimportant part of the total migration of the species studied in this paper, in which case the coasting movements which have attracted so much attention may give a misleading im­ pression as regards directions taken, times of movements etc. of the main migatory flights. The real problem for future research is perhaps " invisible migration ".

SUMMARY 1. Sky-Larks coasted west along the north coast of Cornwall, turned south round the Land's End peninsula and then east, and they continued on east at least as far as the Lizard. Others coasted west along the south coast, turned north round the Land's End peninsula and up the west coast but have not yet been traced further. Both groups included birds which took off over the sea south in the VOL. XLV.] VISIBLE MIGRATION AT LAND'S END. 95 direction of Spain and W.N.W. in the direction of Ireland. 2. Chaffinches had similar coasting movements in both directions, but probably took off over the sea chiefly at night, though some­ times by day in the direction of Ireland.. 3. Sky-Larks chiefly took off over the sea in fair weather and often with a following wind. Both Sky-Larks and Chaffinches coasted mainly against the wind. 4. Starlings took off W.N.W. from the west coast of the Land's End peninsula, coming from inland. A few set off south. Coasting movements were rather indefinite. 5. Migration was seen most commonly in sunny weather with a light wind, and least in fog, heavy rain, or strong wind. It was commonest in the first two hours after dawn, the peak time varying somewhat with the species. The behaviour when starting off, and when crossing the sea, is described.

REFERENCES ALLEN, N. V. (1944). " Migration of Chaffinches and other birds on the south-west coast." Brit. Birds, 37 : 212-213. BANNERMAN, D. A. (1944). "Chaffinch migration on the south-west coast." Brit. Birds, 37 : 177. CLARKE, W. E. (1912). Studies in Bird Migration. London. Vol. I, esp. pp. 221-237, 252-267, 280-323. GOODBODY, I. M. (1950). " Sky-Lark migration in S.E. Ireland." Brit. Birds, 43 : 265-271. HARTLEY, P. H. T. (1945). The Cornwall Bird Watching and Preservation Soc. Ann. Rep., 15 : 13, 15-16. HOLT, E. G. (1950). " Autumn migration along the Bristol Channel." Brit. Birds, 43 : 271-273. HURRELL, H. G. (1944). " Chaffinch migration in the south-west." Brit. Birds, 38 : 10-11. LACK, D. AND E. (1949). " Passerine migration through England." Brit. Birds, 42 : 320-326. LOWERY, G. H. (1946). " Evidence of trans-Gulf migration." Auk, 63 : 175-211. RUTTLEDGE, R. F. (1938). " Bird-migration by the overland route between Killala Bay and Galway Bay." Brit. Birds, 32 : 130-135. SIMMS, E. (1950). " Autumn bird-migration across the South Midlands of England." Brit. Birds, 43 : 241-250. TAIT, W. C. (1924). The Birds of Portugal. London, pp. 52-53. WOOD, J. D. (1950). " Further notes on passerine migration through England." Brit. Birds, 43 : 274-278. (96)

TABLE I. INFLUENCE OF WEATHER ON MOVEMENTS Number passing in best hour Wind Weather Dates in Sky-Lark Chaffinch Starling October (out to sea)

Light Sunny 9, io, 13, 229, 124. -f-, 70 (o, 0), 100, (0, 0, 0), 14, *9, 23, 80, 126, 193, 79, 120, 46, 35, 9> 5o, 24, 30, i.XI 404,215, (—} 433, 75. 400+ 250, 6000, 4600 -f Average 1J9 Average 179 Light Fog (once heavily ft, ID, n, H* 7, 16, (0, 0, 0), (0, 0, 0), overcast) 15, 16, 18 10, 6, 12 0, 2, 0 0, o, 0 Average n Average 1 Light Showery 25 75 788 450 Strong Sunny- 17 124 8 100 Strong Showery 21, 22, 26, 51, 43. ", 0, 0, 30, 0, 0, 496, 28 12 15 300 ^ verage 29 Average 11 Strong Heavy rain 27, 29, 31 °> 9> ° 0, 0, 0 0, 0, 0 Strong Heavily overcast 12 18 to) (0) NOTES r (J) ror Sky-Lane and Chairmen all migrants were counted irrespective of direction;, but for the Starling only those setting off out to sea. (ii) (o) Means none seen but too early in the season for migration to be expected. Such cases have been excluded in calculating the averages, (iii) On 1,XI we counted only for about half an hour around dawn, too early for Sky-Larks.

TABLE 2. SKY-LARK MOVEMENTS AT GWENNAP HEAD Date Wind Coming from N. and Coming from E. and In from out S. or coasting E. outW.N.W .or coasting N. sea N.E. Direction Strength Peak hour Most left Peak hour Most left Peak hour

9.X S.E. Mod. 220 More out S. 0 _. 5 I2.X S.E. Strong 18 Back N. 0 0 I4.X S.E. Mod. 64 More coasting 30 (not noted— ) 6 E. I7.X N.N.E. Strong 49 Mixed m .Mixed 0 18.X None (fog) 10 Coasting E. ' 0 1 19X N.E. Ligh—t 34 Mixed 01 Out W.N.W—- . 0 20.X W. Mod. 24 Out S. 6 Coasting N. 0 2.1.X W. Strong 0 5i Coasting N. 0 22.X N. Strong 3 — 40 Coasting N- 0 23.X N.E. Light 67 OutS.— 150 Out W.N.W. 32 24-X E. Light 283 Coasting E. 70 Out W.N.W. 72 30.x N.W. Light 7 OutS. 185 Out W.N.W. 20

TOT AJ, ...... 779 696 136 NOTES : (i) The peak hour was not always the same for each direction, hence totals do not always correspond with Table i. (ii) When most birds left in one direction, this only is given; " mixed " means that con­ siderable proportions left in both directions ; " more " means some in both directions but a preponderance in one, (iii) Visits normally from about 08.15 hours (sun-time) but on October 20th only in late morning.

TABLE 3. CHAFFINCH MOVEMENTS AT GWENNAP HEAD AND CAPE CORNWALL Wind Direction of Number in Date Direction coasting movement peak hour

13.X. S.E. S. 100 14.X S.E. S.-E. 70 17.X N.N.E. W.-N. 8 lo.X N.E. S.-E. 120 2J.X N.E. W.-N. 23 24.X E. S.-E. «3 2j.X E. S. 788 26.X S.E. 3" 28.X S.E. s. 15 30.X N.W. W.-Ns. . 75 r.XI S.W. S. 400+ NOTE: Two directions are given when the observations were made at Gwennap Head, as the birds turned there, but only on-' direction at Caj>e Cornwall where the coast runs north and south.