<strong>Scottish</strong> Bird NewsBirdSpot - Oh no, it’s a Commic Tern!When I first mooted the idea ofdoing a BirdSpot item for SBN,Jimmy Maxwell immediatelysuggested the subject ofseparating Common and ArcticTerns - so here goes. <strong>The</strong> task ismade easier by the superbphotos taken by Bob Furness inShetland.<strong>The</strong> return of the “sea swallows”to our coastlines means spring isreally here. <strong>The</strong>ir elegant flightand loud calls brighten up anyday. But sometimes the doubtover knowing which speciesyou’re actually looking at can takethe edge off the enjoyment ofwatching these wonderful, fartravelledcreatures.<strong>The</strong> secret to successful IDHow best to tell them apart? I’lllet you into the secret at the end.But first, it is essential to armyourself with one of the “new”generation of Bird ID books -these will provide just about allthe information you need. <strong>The</strong>two that I use most are LarsJonsson’s Birds of Europe, andthe Collins Bird Guide byMullarney et al. <strong>The</strong> latter is lightyears ahead of the field guidesmany of us were brought up on.What a great start the youngstersof today have! I prefer the largeA4 format version, whichalthough too large to take out inthe field, does provide (almost)enough space to do justice to thewonderful illustrations - which inthe pocket version are socrammed together as to bealmost confusing. Or is it just thatmy eyes need all the help theycan get these days?Next do a bit of revision BEFOREyou go out in the field. Timespent in reconnaissance isseldom wasted! Try to rememberthe key features that you shouldbe looking for: Common Tern -dark wedge on the upper side ofthe primaries, shorter tail andlonger legs when perched;Arctic Tern - Translucentprimaries with no dark wedge(but with a dark line along thetrailing edge), longer tail andshort legs, often with a greyishwash on breast and belly.<strong>The</strong>n find a place to watch yourterns. It’s best not to go to acolony where the melee oftwisting and chasing birds makesidentification difficult. Better topark yourself on a headlandsome way from a colony and pickthem off one by one as theycome and go. Common Ternsgenerally fish closer inshore thanArctics, and so are often theeasier of the two to get prolongedviews of. To see Arctics you mayneed to visit a more exposedheadland close to tidal rips.One of the problems with“commic tern” ID is that thebrightness and angle of light canmake the plumage featuresdescribed in the field guideseither glaringly obvious orimpossible to see! So it is best toconcentrate on structure andshape, particularly that of thehead and neck and the shape ofthe wings.Common TernSlightly longer head and neckthan Arctic, flatter crown andlonger bill give a slightly “mean”appearance. A useful plumagefeature that is only mentioned inpassing in the field guides is themore extensive wedge of whiteon the lores (between the billgape and the eye) of CommonTern, which further emphasisesthe long-headed/long-billedappearance (to my eyesreminiscent of a miniatureCaspian Tern!).<strong>The</strong> head end thus projects wellforward of the leading edge ofthe wings - which in combinationwith the shorter tail gives thewings a more central position onthe body. Primaries tend to havea more convex trailing edge,giving the wings a fullerappearance. Flight a little strongerand more stable than Arctic, andwhen fishing, hovers and divesdirectly into the water.Arctic TernShorter bill and shorter and morerounded head appears sunk in tothe shoulders. In combinationwith the long tail, this takes thebirds centre of gravity furtherforward than on Common. Trailingedge of primaries tends towards aconcave outline, giving the wingsa sharp appearance, especially atdistance. Flight generally dancing,bouncy and erratic, perhaps themost graceful of any British bird.However, beware of the CommonTern’s display flight (withexaggerated deep wing-beats)which is extraordinarily elegant.Finally, the Collins Guidedescribes their distinctive fishingbehaviour well: “often dives with‘stepped hover’, dropping a shortdistance and hovering againbefore final plunge”.Hopefully you’ll be able to seemost of these features in thephotos. If not, the illustrations ofCommon and Arctic Terns in flightin the Collins Guide show allthese features well.And finally the secret - practice,practice and more practice.Clive McKayPlates 53–56 (above). Arctic Tern © Bob Furness & Clive McKay.Plates 57–60 (below). Common Tern © Bob Furness & Clive McKay.<strong>Scottish</strong> Bird News70<strong>Scottish</strong> Birds <strong>29</strong>:1 (2009) <strong>29</strong>:1 (2009)<strong>Scottish</strong> Birds 71
Birding in Scotland<strong>Scottish</strong> BirdsPlate 61. Black-throated Thrush, Isle of Bute, February 2007 © Phil Kirkham.Black-throated Thrush, Isle of Bute,January–March 2007R. FORRESTERMcMillan’s kitchen window, although it oftendisappeared for long periods of time. AlthoughI was keen to release the news, there wereobvious access difficulties, as the garden couldnot be viewed from a public right of way andIna McMillan did not want a continual string ofbirders in her kitchen. I discussed the situationwith Angus Murray of Birdline Scotland and itwas agreed that information could be releasedlate on Sunday 28 January, thus avoiding apossible large influx of birders over theweekend. <strong>The</strong>re was public access to an openarea of ground 40m to the rear of Elmlea andthe initial announcement on Birdline Scotlandadvised that the bird might possibly beviewable from there, but Elmlea was notpublicised as the exact location where the birdhad been seen. <strong>The</strong> bird was seen on theMonday by visiting birders and over the nexttwo months at least 200–300 birders visitedthe island and saw the bird, which continued tofrequent Elmlea, but probably spent more timein a large garden to the rear and which wasBirding in Scotlandpartly visible from the public right of way.Visiting birders all behaved very well and noneof the residents voiced any complaints. In factit proved an excellent public relations exercise,with Ina McMillan very generously invitingmany birders to view from her kitchen window.<strong>The</strong> bird was last seen on 26 March.Description<strong>The</strong> bird was similar in size and structure toCommon Blackbird, a species often nearby fordirect comparison. It was fairly uniform greybrownabove, with light edging to tertials andcoverts. <strong>The</strong> underparts had a light grey washwith dark flecking, particularly on flanks. <strong>The</strong>throat and upper breast feathers were blackwith pale edging, giving a ‘scalloped’appearance. <strong>The</strong>re was a yellow base to thelower mandible, with the rest of the billblackish. Dark legs. Dark eye.Ron Forrester, <strong>The</strong> Gables, Eastlands Road,Rothesay, Isle of Bute PA20 9JZ.Ina McMillan who lives at Elmlea, Minister’sBrae, Rothesay on the Isle of Bute feeds birdsin her garden each day. She knows the regularspecies, but does not claim in any way to haveany expert knowledge of birds. On 18 January2007 she saw an unfamiliar bird in her gardenthat she could not name, although shebelieved it to be a species of thrush. As shecould not find it in her book of garden birds,she visited the local library, which by chancehad a copy of Simms’ Thrushes, from whichshe identified the bird as a Black-throatedThrush Turdus ruficollis.<strong>The</strong>re was some disbelief of her claim by theinitial persons she contacted, but fortunatelyher insistence and persistence paid off. It wasnot until the evening of 23 January that shecontacted a local birdwatcher, Ian Hopkins, andhe visited her house early the next day. Seeingthe bird briefly and believing that the identificationwas correct, he telephoned me andasked if I would check it out to confirm identification.I arrived at her house and saw the birdfor 2–3 minutes at 10:15hrs at a distance of10m when it was perched in a Eucryphia tree.Identification was straightforward and easilyconfirmed as a 1st-winter male Black-throatedThrush. I saw the bird again on 25 and 26January at distances down to 25ft (8 m),although it proved elusive and was only visiblefor 2–3 minutes on each occasion.Up to that time the bird had only been seen inthe small garden of Elmlea, a mid-terracedhouse and it had only been viewed from InaPlate 62. Black-throated Thrush, Isle of Bute, February 2007 © Tom Marshall.72<strong>Scottish</strong> Birds <strong>29</strong>:1 (2009) <strong>29</strong>:1 (2009)<strong>Scottish</strong> Birds 73