Tuesday, 27 October 2015

27th October 2015 Beachy SE1-2

Marsh Harrier 1 female-type
Pallas's Warbler 1
Short-toed Treecreeper 1
Long-tailed Tit 10

Short-toed Treecreeper in the Old Trapping Area (John Cooper)
One of JFC's superb images showing the long billed appearance, brown fore-supercilium, off-white rear supercilium, dark brown forecrown, rather plain mantle with patterning virtually restricted to pale shaft streaks, white throat contrasting with greyish-washed breast and brownish-suffused flanks and isolated white spots at the tips of the primaries. In an attempt to compare critical detail the wing has been photographed off the monitor and shown below:
Beachy (left), Short-toed Treecreeper (centre) and Common Treecreeper (right)
Colour-coded captions below from http://10000birds.com/terror-from-the-trees.htm
(Italics comparing to JFC's image of the Beachy individual)

Pink: the pale pattern on the alula is usually more extensive on the outer web on Common than on Short-toed, but there is considerable overlap. On the birds above, it’s not really working.
(Complete narrow pale fringe to alula visible on JFC's image)

Blue: this is quite possibly the most important feature and the one most likely to be assessed without a photograph to analyze. The pale bars on primaries 6, 7, and 8 (counted from outside towards the center of the wing) overlap to almost equal extend in Common, forming a “stairway”. In Common, there is considerable overlap between primaries 7 and 8, but almost none between 6 and 7, forming a large right-angled blackish “corner” on the folded wing. Note also that the border of the pale bar towards the tip forms a more prominent saw pattern in Short-toed compared to Common.
('Stairway' a very close match lacking the right-angled blackish 'corner'. Perhaps just as important are the shape of the tips of the pale bars being particularly saw-toothed at the tips)

Red: A small pale spot is usually present on the fourth primary in Common, but often lacking in Short-toed.
(Position of outermost bar a neat fit with Short-toed Treecreeper)

Green: the dark wing bar below the pale wing bar on the secondaries is quite evenly broad in Short-toed, but less well-defined and narrowing towards the primaries in Common.
(Dark wingbar clearly consistently broad and not narrowing)

Yellow: the visible spacing of the primaries 6 to 8 is rather even in Short-toed, but more uneven in Common, with the tip of p7 being very close to p8, and a big step between p6 and p7. This is sadly not visible on the pictures above due to an unfavourable angle on both pictures.
(If anything, the pale tips to the primaries appear even more isolated than that of the Short-toed Treecreeper)
There are more features on the wings, e.g. regarding the exact shape of the pale primary tips and the contrasts between the outer & inner web and the tip of the largest tertial.
(Inner web of the largest tertial clearly dark and therefore hardly contrasting with the outer web)
Short-toed Treecreeper (left Liege, Belgium) (right Beachy) from: 
Being of the closest of the forms B.c. megarhyncha of Short-toed Treecreeper to the south coast of the UK it is reassuring the individual photographed at Liege, Belgium proves a very close match. It is interesting to compare the many striking similarities including most-importantly the long-billed appearance of both individuals, the narrowing tips to the pale bars being pointed (saw-toothed) at the tips (more rectangular on Common), the consistently broad dark wingbar, the dark inner web of the longest visible tertial and the isolated white tips to the primaries lacking white hook-backs. In addition, the contrastingly white throat is striking on both birds as are the similarities of the near-identical pattern, colouration of and streaking to the crown, the shape and colouration of the supercilium, strength and width of the eye-stripe, patterning to the ear-coverts, colouration of and patterning to the mantle, the shape of the pale tip to the alula and colouration and pattern of the tail with regard to both the darker shafts of the longest tail feathers and in darkening distally on both individual.