CO NT EN T S The Scottish Zoological Park; and other Editorial Notes

An Account of the Destruction of Methil Dock Gates by Marine Organisms (I llustrated)- J ames Ritcltie, 1J£. A. , D .Sc.

O n the Decrease of Blackgame in Scotland-L eonora J effrey Rinto1tl and Evelyn V. Baxter ( Contimted from p. r 3)

Bird Notes from Fair I sle, r 92 6- Surgeon Rear-Admiral .f. I:!. Stmlwu se

Notes on the Coccidce of Scotland- E. Ernest Green, F E .S. , FZ. S. (Concluded)

Notes :

A Large Dog Otter- Donald Ross, 44 ; Risso's Dolphin stranded in Caithness-Dr J ames Rite/tie, 6o ; Records of large Foxes-riarry fl. Bootlt, 6o; Eastern Less~r vVhitethroat on Hyskeir-J olm Bain, 44 ; Leach's Fork-tai led Petrel in D umfriesshire - riuglt S. Gladstone, 44 ; Wild Geese alight ing on Trees-Alec. T. Crmvjord, 6o ; Further Records of breeding of Pochard at Dudclingston Loch- Dr J. Jl£. Dewar, 6r ; The Golden Eagle in Galloway-Sir Herbe1·t Ll£axwell, 62 ; Sweden to Britain : Migration of Rough­legged Duzzard- Einar Lonnberg, Stocldwlm, 63 ; Young John Dory off \tV es tern Inverness ·sh ire-A. C. S tepltm, 44 ; Unusual Colour Variety of Haddock- Dr J as. Rite/tie, 62.

Book Notices

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The Scottish ;-,!, Naturalist

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88 THE SCOTTISH NATURALIST

THE SPIDER FA UN A OF THE WESTERN ISLA NDS OF SCOTLAND

By W. S. BRISTOWE, B.A., F.Z.S.

THE July of 1922 was spent cruising amongst th e islands off the West Coast of Scotland in a 16-ton yawl, and most of the time spent ashore was g iven up ·to th e collection of spiders. Ten islands were visited, but in most cases I only had a few hours on each, owing to my companions being yachtsmen rather than naturalists, and in this time I naturally cannot claim to have made anything like an exhaustive collection on any of them.

In the present paper I have combined all the scattered records of other collectors with mine to form a list of the spiders known up till now from these islands. The islands visited in chronological order were as foll ows:-

The Isles of the Sea or Garvelloch I sles (outside Scarba), Kerrera (Oban), Mull, Eigg, Rum, Skye, Priest I sland and two of the Summer Isles off Ross and Cromarty, the Outer Hebrides (Lewis and Harris), and the Shiant Isles (off Lewis).

On the whole the spider faunas of the different islands up the coast of Scotland appear to be very simila r. A ll the species found on the islands a re common on the mainland

)

but the converse is far from being true. It is said that broadly speak ing the temperature fa ll s

I oF. for each degree of latitud e north or south of the equator, and that the same fall occurs for every 300 ft. ri se in altitude. The faunas of mountain tops and arctic reg ions are often compared, but in these comparisons the lowness of the t emperature is usually looked upon as the limiting factor. In actual fact th e mnge of temperature is probably of equal importance or, to include another factor, name ly wind, which would in practice be difficu lt to eliminate from our consideration, we can put forward another factor of importance which can be called "exposure." It is probable that both "temperature" and "exposure" as defined above

I ·

SPID E R FAU NA OF WES TERN ISLANDS OF SCOTLAND 89

act as limiting factors on different species, and, whilst realis ing tha t they cannot really be sharply differentiated, since the t empera ture va ries appreciably with exposure, some notes follow which show the effects on d istribution of these two roughly defin ed factors.

W eb-building spiders are res tricted to the more sheltered situations on the island s. T etragttat!ta extmsa is a wide­spread and hardy species found from the Mediterranean to L apland and from temperate to a rctic N orth A merica. This species is common on the is lands but its relatives T. so!andrz'z' and T. pz'nz'cola, although found quite far north on the mainl and, do not even approach the west coas t of Scotland. These species a re most comm on ly met with in woods . . Of the 40-odd Epeirids recorded from a rctic regions the majority a re · res tricted to the ma inl ands of arctic Europe a nd A merica. N o rep resenta tives at a ll of th e family A ttid ae we re found and the only one recorded in this li st is Euop!t1J'S erratz'cus, from A rran, which is otherwise comm on un der stones on the mainland. A bout 20 species have been recorded from arctic regions, but these a re chiefly from the mainlands of arctic Europe and A merica as in the case of the a rctic A ttidae.

The most successful forms are those which live under stones, etc. (Linyphi idae, Lycos idae), or in holes and burrows (Segestrz'a, Textrz~-o, Amau.robz'us and certa in Lycosids). T hese will escape to a great extent both the limiting factors with which we a re dealin g. Major Hingston has shown * how on Mount E veres t at IJ,ooo ft. the temperature beneath a stone va ried through only 1 2 ° F. du ring the t wenty-four hours, ·whilst in the same period the temperature of th e air va ried through 44° F.

If our contention is correct, namely, th at ex posure is a n importan t limiti ng factor, in comparin g t he faun as of mou ntain tops and the arctic, we shoul d make th e com­parison more especially with a rctic island s. In th e co urse of our crui se a number of mounta ins were climbed , and a lthough some were on the ma inland I give below a list of th e species collected on each. On 8th July I climbed

·•· Geograj;ltical J ottrnal, May 1925.

go THE SCOTTISH NATURALIST

Halival (Rum). At the summit of this mountain, which is 2300 ft., several alpine-arctic plants grow, such as Silene acaulis and various Saxifrages. By turning over the stones amongst these I obtained the following spiders :-

Robertus lividus. Leptyphantes z immermannii.

, pallidus. Ceratinella brevipes. Centromerus prudens. M acrargus abnormis.

Crypha?ca silvicola. Troclzosa terrico!a. Tarentula pulveru!enta. Nemastoma lugubre

(Opilionid).

On the following day the weather forced us to stay in Loch Nevis, so we set out on foot to climb Ladhar Bheinn {3300 ft.). A very heavy mist descended on this mountain, however, so we had to content ourselves with a 2000 ft. one close to it. Here I collected the following :-

Robertus !ividus. Leptyplwntes zimmermannii.

, erzca?us. Centromerus prudens.

M acrm'gus abnormis. N emastoma lugubre

(Opilionids). Mitopus 11lorio.

On the way down I found the webs of Epei1'a cornuta in a valley between the two mountains a few hundred feet from the summit.

On 12th July we anchored in Broadford Bay (Skye) and I climbed Ben-na-Caillich (2400 ft.) which is one of the Red Hills. On the way up, at 1000 ft., I captured Lycosa traillii, which looks like an overgrown L. amentata. At the summit by turning over stones I collected the following:-

Robertus lividus. Leptyphantes zim11ler11lmmii.

, w!tymperi.

M aro .falconerii. Neriene rubens. Pa?ci!omta g-lobosa.

On our return journey we again came to Skye, anchoring this time in Loch Scavaig (25th July) and ascended one of the Cuillins, Sgurr Dubh-N ada-dheinn (3000 ft.). Conditions at the top of this mountain were very different. Vegetation, consisting of Silme acaulis, Saxifraga oppositifolia, etc., was very scarce, and the summit really consisted for the most

SPIDER FAUNA OF WESTERN I SLANDS OF SCOTLAND gr

part of jagged bare rock. The best part of an hour's hunting produced but three species:-

l-f£!a£ra frz"g-ida . Coryphceus lw!mgnn£. ~Va!ckencera capito.

When we reached Lochinver on 18th July (our turning point) we climbed Suilvin (2400 ft.). The following were collected :-

Robertus lz'vidus. L eptyplzantes zz'mmermmmii. Hz'! a ira fr£gida. Caledonia evansii. M acrargus abnormis.

Pceci!oneta g!obosa. Tarmtu!a pulverulmta. N emastoma lugubre

(Opilionid).

An examination of these lists shows us immediately that all the species are either forms which live under stones, or in the case of Tarmtu!a a nd Troc!tosa, burrow manufacturers which wander about on the g round when conditions are fa vourable. I noticed that just below the summit on the lee side of the mountains the number both of species and individuals always increased rapidly, and by comparing my results with those of Dr R. Jack son from some of the higher mountain s of Scotland, one find s that two extremes of altitude exist in any g iven locality:-

I. The extreme altitude at which a species will occur at the summit (limiting factor "exposure").

z. Extreme altitude below a summit (always greater than the last owing to the limiting fact or here b eing "temperature").

Three of the commonest species on the islands are JJ!Jeta meriance, Segestria senocu!ata, and Textn>c denticu!ata, None of these are found at high altitudes, nor do they ext end into the arctic (the nearest approach be ing Textn~1: in the Orkneys). It seems probable, th erefore, that temperature governs the d istribution of these species. Lycosa pu!!ata, Tarentu!a pu!veru!enta, Robertus Nvidus and the Opilionid Nemastoma !ugubre on th e other hand a re limited to a greater degree by exposure than temperature. Their range extends into the arctic and they are to be found at fairly hig h altitudes on the Scottish mountains. The Lycosa does

THE SCOTTI SH NATURALIST

not seem to like the summits, but Dr Jackson record s it on the Cairngorm s in sheltered situation s at between 3000 and 3500 ft. Tarentula, Robertus, and Nemastoma have been collected on summits at 2400 ft., but in the Cairngorms below the summit at between 3000 and 3500 ft. The hardiest species appear to be .Hilaira fngida, COJyjJ!ta:us ltol11lgnni, Leptyplzantes whymperi, and Walckenaera rapito. The first two have been found at th e summit of the Cuillins (3000 ft.) and Cairngorms (4300 ft.), and their range in the arctic includes various islands and is probably wide-1-Iilaim has been recorded from Greenland and J an Mayen, and Coryplzmus from Nova Zemlya, Spitsbergen, Bear Island, and J an May en. L eptyplzantes w!t;mzperi, which I found at the summit of Ben-na-Caillich (2400 ft .), was found by Dr J ackson at the summit of the Cairngorms (4300 ft. ), and on Ben Nevis above 4000 ft. wherever stones occurred am ongst the snow. This species has been recorded fr om Greenland. Walckencera capito was one of the three species at the summit of Dubh-Noda-dheinn (3000 ft.) and Dr Jackson found it at the summit of Cairntoul (4200 ft.). This species has not been recorded from the a rctic up to the present time.

Before leaving the subject of distribution I should like to draw attention to the similarity of the spider fauna of the western islands of Scotland to that of ( 1) the Irish Islands, and (2) the Norwegian I slands. Mr D. Pack Beresford records 108 species from Clare Island which is situated off the west coast of Ireland. His list includes all the species most commonly found on the Scottish Islands such as Seg-estria senoculata, Textrz~r denticulata, C1J'}Jhmca silviro!a, A maurobius simi!z'.s, Robe1'/us lz'vidus, M acrarg-us abnormis, Engone arctica, Tetrag-natha extensa, ll1eta meriance, M. seg-mentata, Lycosa pul!ata, T rocfzosa te1'ricola, Tarentula pulveru!enta, Xysticus cristatus, and the Opilionid N emastoma !ug-ubre. In addition three A ttids are recorded, namely, Neott reticulatus, Euoplzrys frontalis, and Heliophamts cupreus " in sheltered nooks facin g South or vVest."

Cond itions experienced on the Norwegian coast are very simila r to those on the west coast of Scotland; when near

SPIDER FA UNA OF WES T ER N I SLANDS OF SCOT LAN D 93

Bergen for a short time during the summer of 192 1 I made a sm all collection of 42 speci es, and this was sufficient to show how strikin gly similar the spider faun as of the two regions are. A ll were British species and the list included a ll the most typical Scottish forms such as :-

Segestria senocu!ata, T extn:-r dentim!ata, LJ;cosa pzt!lata, T7'ochosa terricola, A maurobizts ft1Zest7'alis, Robertus !ividus, T !teridion bel!icosttm, Leptyphantes r.:immermamzii, En'g·one arctica, P ll?ci!o7teta g!obosa, Mac7'arg·us abnor111is, M eta meriam:e, and the opilionid s Nemastoma !ztgttbre, lJ!!egabtt7ms diadema, and Obisizt71Z 11tztscorzt11l.

The majority of spiders included in the li st which follows belong to the dominant section which have colonised the whole of the British Isles. A few a re typical southern species such as D rassodes pubesce1Zs, Xyst icus p ini, LJ;cosa mmulata _- but only s ingle records for these species exist, a nd it is possible that the iden tification is at fault. Some a re northern species- En'gmte a?'ctica, T!Valckenmra crrpito, T !teridzo1Z bellicosum, and Lycosa traillz'i for instance-and three may be cl assed as arctic forms, namely Coryphll?us !tolmgreni, H ila ira fn'gida, and L eptjpltantes w!tymperi.

I a m indebted to Mr E . J. Pearce and Mr H. B. Cott for small collections of spiders from Jura and Skye respectively, and, in addition, I am including an unpublished list of forty species made by Mr A. Pickard from the island of Colonsay and written into a copy of his uncle's paper on" The Spide rs of Scotland," published in T!te Entomologist, 1877 (the late Rev. 0. P ickard-Cambridge). This paper has recently come into my possession and, seeing that Mr A. P ickard was in the habit of sendin g his uncle spiders to identi fy, the Jist is in all probability perfectly tru stworthy. A list of species has been collected from the records of the late Mr W. E vans for A rran and Bute, which embodies the earlier records of F. L. Grant, 0 . P. Cambridge, and Professor Traill. In addition to solitary records for which references are given la ter, I include a list of the spide rs of St Kild a made by 0. P. Cambridge and records of Chelifers from some of the islands published by R. God frey.

With these add itions the list comprises 14 0 spiders (one

·-

94 THE SCOTTISH NATUR ALIS T

of which, 1/llz'cryphantes beatzts, Camb., is new to Scotland), I I Harvest spiders, and 3 Pseudo-scorpions. I am g reatly indebted to Dr A. Randell J ackson, who has himself made valuable additions to our knowledge of the Scottish Spider Fauna, for examinin g practically a ll the spiders I collected and checking my identificat ions.

The initials inserted beside the different localities refe r t o the records and collections of the following:-vV. S. B. = W. S. Bristowe; 0 . P. C.= Rev. 0. P ickard-Cambridge ; H. B. C. = H. B. Cott; W. E . = W. Evans; R. G. = R. Godfrey; F. L. G.= F . L. Grant; J. E . H. = Rev. J. E. Hull; E. J .P. =E. J . Pearce; A. P. =A. Pickard; S imon= E. S imon ; Strand = E. Strand.

Oonops pulcher, Tempi. . Segestria senoculata, Linn ..

Drassodes !apidoms, Walck.

trog!odytu, C. L. K.

pubescens, Thor. Ptosthesima petiverii, Scop.

Micaria pu!icaria, Sund. . C!ubioua trivia/is, C. L. K.

lwloserica, De Geer.

?'ec!wa, 0. P. C. diversa, 0 . P. C. comta, C. L. K. terrestris, \,Y estr.

ARANEJE.

Bute (W. E.). Bute and Arran (W. E.); Colonsay

(A. P.); I sles of the Sea, E igg, K.errera, Priest I s., Summer I s., Lewis (W. S. B.).

Bute and Arran (W. E.); Colonsay (A. P.); Skye (H. B. C.); E igg, Rum, Skye, Kerrera, Mull, Priest I s., Shiant Is. (W. S. B.).

Bute and Flannan I s. (W. E.); Mull (W. S. B.).

Arran (W. E.). A southern species. St Kilda (0. P. C.); Priest Is., Summer

Is. (W. S. B.). Colonsay (A. P.). Arran (W. E.) ; Orkneys (0. P. C. );

Lewis (W. S. B.). Bute and Arran (F. L. G.); St Kilda

(0. P. C.); Colonsay (A. P.) Bute (W. E.). Bute (W. E.). Arran (W. E.). Bute and Arran (W. E.).

(To be continued.)

NOTES 95

NOTES Large Dog Otter.-! was rather surprised to see in your las t

issue a dog otter weighing 21 lb. described as large, for in my article on the length and weight of otters in Tlte Annals of Scottish Nat1tral History (rgog), I gave the average weight of an adult dog otter as more than this, viz., from 2 r to 24 lb. At the same time, and also in the rgor vol., I gave instances of really large dog otters, viz., those on record of over 30 lb. in weight. The largest otters I ever came across were those living in the sea in the Inner Hebrides, and it would be interesting to have statistics of such from readers living or visiting these islands, for some of the skins I saw in farm­houses and crofts there must have belonged to enormous otters of

30 or more pounds in weight-H. W. RomNSON, M.B.O.U., etc.

Gannets on the Bass Rock.-As I have not seen many notices concerning the time the first Gannet's eggs are laid on the Bass Rock, it may be of interest to state that the first egg was found thi s year on 1st April, which is earlier than usual.

As I have, as yet, had no returns from the roo young marked there with rings last year, perhaps your readers will examine· any dead Gannets they may come across for rings and record the same, especially so as the on ly two records of those marked there in a former year are somewhat puzzling.-H. W. RoBIN SON.

Hawfinch nesting in Kirkcudbright.-On 2 rst April, I was handed a I-Iawfinch which bad been picked up dead near Dalskairth, Maxwelltown, Kirkcudl>right. Last year (1926) a pair of these birds nested at Dalskairth and hatched their young, which, however, were destroyed just L>efore they could fly.-Hucu S. GLADSTONE.

Great Snipe in Forfarsbire.-A rushy marsh at E lliot is a favourite resort of snipe on arrival from oversea. On 13th August last what at first sight seemed to be a very small W ooclcock feeding along the muddy margin of the marsh proved to be a Great Snipe. Several Common Snipe were partly visible in the vegetation on the opposite side, thereby enabling the two species to be compared. Probably it was the same bird which was seen again on the r6th on a grassy plot occasionally subjected to flooding, and fin ally on the 2oth at the marsh. -DoUGLAS G. H uNTim, Arbroath.