Monday 6th July 2009 Cornwall Bird Reports

Pendeen – A four hour seawatch from 8am at Pendeen today produced European Storm Petrel (20+), Balearic Shearwater (2), Blue Fulmar, Common Scoter (2), Roseate Tern (2 lingering) and an Ocean Sunfish (Thanks S Votier & S Bearhop)

PorthgwarraCory’s Shearwater (2) flew past Gwennap Head late morning

HayleBlack-tailed Godwit (1), Dunlin (1), Redshank (10), Whimbrel (2) and Curlew (50+) on estuary this afternoon.

Padstow Med Gull (9) on Camel Estuary this morning.

2 thoughts on “Monday 6th July 2009 Cornwall Bird Reports

  1. John Foster

    Sorry, but the two terns lingering at Pendeen were Arctics for the following reasons. Structurally they didn’t have long enough tails for Roseates and looked hunched, with their centre of gravity apparently between their shoulders as do Arctics. Plumage-wise they weren’t strikingly pale and didn’t have the dark wedge in the outer primaries. They had a neat dark trailing edge to the primaries on the underwing. They didn’t have the exaggerated bouyant flight action of Roseates. Roseates feed by power-diving forwards into the sea, these birds hovered, flipped, dived vertically and dipped at the surface.

  2. Steve Votier

    John Foster asserts that the 2 terns lingering at Pendeen were Arctic terns. Assuming that they were same birds seen earlier in the 2 (and this is a reasonable assumption given that they were the only terns we noted during the morning) we very strongly disagree. We carefully watched these birds on and off for about an hour from the base of cliff and they were most definitely Roseate Terns. Having never seen this species in the SW (although we do have extensive experience of Roseate Terns in Norfolk, Northumberland, Borders, Lothian, Anglesey, Ireland, The Azores and one bird summering in an Arctic Tern colony in Shetland), we were very careful to check their identification. These birds were strikingly pale, recalling Sandwich Terns in colour, lacking the grey tones of Arctic/Common. They also showed a dark wedge in the outer-primaries (contrary to the comments above) – although this was apparent only at close range (the wings appeared largely uniform at distance). The structure was also consistent with Roseate, with a relatively long head and bill, lacking the ‘flown into a wall’ look of Arctic. The flight action was also distinctive, being almost Little Tern-like at times (rather jerky at times) – nevertheless this difference was not always apparent as this jerky flight varied depending on wind conditions and was less obvious when these birds were actively foraging. The foraging behaviour described by John Foster is a rather simplified version of events. Foraging differences between the Arctic/Common/Roseate group are subtle and far from absolute differences. Moreover, on occasion these birds were seen to dive forwards from a relatively low height into the water, which is consistent with Roseate and different from the normally high diving Arctic. There were also other valid features we could see at close range. One bird had much longer tail streamers than the other, as well as pink flush to the underparts (this was only visible on the very closest views), perhaps suggesting a pair. The black extended well down the nape and the bill looked long and all black.
    In summary these birds were Roseate Terns for a number of different reasons. We thank John Foster for his comments but respectfully suggest that he re-thinks the identification. These birds are not always easy to identify on a seawatch, but these presented an excellent opportunity to exam this species in some detail for a prolonged period.

    Steve Votier & Stuart Bearhop

Leave a Reply