The Ness Terns Good

After an intense week of exams, a day’s birding on 19th May was on the cards as a break from revision. I opted for a day’s birding by foot at Girdle Ness, what with the recent run of easterly winds. When I woke up that morning to see crystal clear blue skies my hopes of passerine migs immediately dwindled, but out of dedication I decided to work The Ness anyway.

Arriving at 11, I worked the whole headland from the North Bank to Nigg Bay. No passerine migrants were at the allotments, but a House Martin was hawking the golf course here. I proceeded down to  the sycamore, where a resident Sedge Warbler and a Whitethroat sang, and then along the North Bank. It was all seeming quiet, with a smart drake Goosander by the Skate’s Nose with Eiders being the best of it along this stretch. The Battery managed to oust my suspicions of there being any migs at the Ness whatsoever, only holding yet another resident Sedgie and an endearing family of Pied Wagtails.

It was clear that the Ness was quiet, yet without reluctance I continued my circuit down to Greyhope Bay, where there was finally some action. Firstly, a group of 25+ Purple Sandpipers were a pleasant surprise as numbers tend to dwindle post winter. It was pleasant to see many of them in summer plumage with their all dark bills. One bird sported several colour rings, the colour scheme of red and turquoise on the right leg and yellow on the left indicating that this bird had been ringed by the local Grampian ringing group. Unfortunately I couldn’t read any of the rings due to a harsh wind and distance. Alongside them was a summer plumaged Dunlin.

locally colour ringed Purple Sandpiper, Girdle Ness (19/5/12)

My concentration turned towards a fairly substantial group of terns widely spread out on a couple of clumps of rocks to the right of the Purple Sandpipers. Overall about 60 Common Terns were present, amongst them which were a maximum of 10 Arctic Terns, and about 30 Sandwich Terns. The Sandwich Terns were largely concentrated on the furthest left clump of rocks, where only a few Common Terns were sat. As I scanned through the Sandwich Terns for the first time I picked out an outstandingly pale tern that was largely concealed behind a Sandwich Tern but about the same size as a Common. Very interested, I waited patiently to get a full view of the bird. In the mean time I moved the scope from the bird in question to the few Commons that were present on this particular rock, and it became clear that the bird in question was much paler than all of them. After 5 minutes the Sandwich Tern moved aside, revealing that this mystery tern had a largely black bill with vivid red legs…

I was certain this was a Roseate Tern. The wind was blowing at a rate of knots and my eyes were watering so I was struggling to concentrate fully on the bird. Out of determination against the conditions I examined the bird, moving to the primaries and tail to see if the bird had the diagnostic outstandingly long tail streamers. On inspecting the streamers, I became concerned. They seemed quite short, not extending outstandingly far beyond the wing tip as expected from a bolt on Rosy; in fact only very slightly extending beyond the wingtip. An inspection of the primaries didn’t seem to show the obvious dark trailing edge to the outer primaries contrasting with the uniformly pale inner primaries, which I’d  have expected to have been obvious on this bird. I now wasn’t 100% sure, but nevertheless got a few digiscoped pics, the best of which are below. At one point all the terns took to the air, but I wasn’t able to catch on to this bird in flight. They landed again, and on the basis of its outstanding paleness I relocated the bird in question on a seperate set of rocks where all the terns had now congregated. It remained here for 10 minutes, before the whole flock took to the air and most flew out to sea.  Thus I hadn’t heard it call or seen the streamers in flight…

Roseate Tern, Girdle Ness (19/5/12). In its original stance,where it had previously been hidden behind a Sandwich Tern

in its second stance

Despite the potential set backs of the primaries and length of the streamers, I feel there is enough evidence to confirm this as a summer plumaged Roseate Tern. I have consulted a number of people about the bird, and the majority have been pro Roseate.  The following pro features were noted at the time and also from photos:

• Striking uniform paleness of upperparts. Initial eye opening feature, outstandingly paler than nearby Commons. Harsh lighting only slightly exaggerate the true outstanding paleness of the bird.  Mantle particularly pale.

• Underparts similarly an oustandingly pale white, as evident in pics where this part of the bird is not victim to harsh lighting.

• Bill appeared largely black in the field (more so than shots show) with some subtle deep red at the base.  Decurvature and length in comparison to Commons was striking.

• Primaries uniformly pale white, not showing outstanding dark primary wedge as on many of the Commons present.

• Black outer primary visible on the lower wing tip in the last three shots. Zooming on this area of the bird on the camera/computer reveals this to be the case and not dark colouring from the rocks behind.  This is particularly evident in the first of the last three shots, contrasting with far paler other primaries.

• Slightly smaller than Commons with strikingly bright red legs.

• Elegant and ‘neckless’ jizz clear. When combined with lengthy, decurved bill gave it a somewhat ‘top heavy’ appearance.

• Extremely dark cap with gap by eye creating semi-circular shape and ‘slit-eyed ‘ effect (Collin’s shows in illustration of spring birds)

Regarding the potentially concering feature of the streamer length, I believe that this feature does not cast great doubt on the ID of this bird as a Roseate. Variation in streamer length amongst Roseate Terns is well documented. I spoke to a local birder that deals with the tern colony at the Ythan Estuary, who told me that of 4 adult Roseate Terns in the colony last year two had the standard outstandingly long streamers extending well beyond the wingtip, whilst one had streamers extending just beyond the wingtip (like this bird) and one which had barely any streamers whatsoever.  With this in mind and also that this is almost certainly the same one seen at the Ythan the week before where all terns at Girdle Ness come from, streamer length arguably isn’t a huge concern in this respect and means that this was probably the Ythan bird.

Regarding the lack of contrast between the inner and outer primaries, the bird does show a dark outer primary feather which is pro Roseate. In addition, the same local birder suggested that the contrast between the inner and outer primaries becomes more obvious later on in the summer and that the primaries as a whole are more likely to be bleached and thus not show the same extent of obvious contrast during the spring. This gradual strengthening contrast between the inner and outer primaries in late summer could feasibly correspond with the more extensive red at the base of the bill that many Roseates have acquired by this time, and perhaps also in the development of tail streamers to their full length, even though this varies regardless.  This could well be why this bird didn’t show such an obvious contrast between the outer and inner primaries and could potentially explain the streamer length conundrum.

With most consulted having agreed this is a Roseate Tern and the vast majority of pro Roseate features that the bird showed, I am happy with it as such. Whilst I am confident, any opinions on this bird would still be appreciated; please leave a comment if you wish to share your opinion. 

***

Enthused, I moved on and had a look offshore from the Coo which was quite fruitful, with hundreds of Kittiwakes and Auks heading north and also a considerable passage of Gannets. This kept me entertained and was nicely rounded off by 2 Manx Shearwaters north. The walled garden revealed 11 Wheatears, whilst another was at an otherwise quiet South Bank. Nigg Bay held 3 Red-throated Divers but little else. Having completed my circuit, I made my way back, cutting through the golf course. As I went back along the North Bank I bumped into Mark Lewis, who I showed my photos of the tern to. I soon found myself doing a whole round of the Ness with him, keeping a look out for the tern at Greyhope Bay once again. It was pretty unfruitful at first but very enjoyable company. Things finally kicked off as we were both sat at Greyhope Bay as an Osprey was picked up offshore heading north, a riveting patch first for us both and a big highlight of the day. As we headed through the allotments a Goldcrest was seen, the only genuine migrant of the day.

I didn’t get home until 8pm, having been at The Ness for over 7 hours (!) . Retrospectively it was a great day’s birding at The Ness and my efforts had been rewarded, despite it being quiet on the wider scale of things.

Thanks for reading,

Joseph