16th August


After the miserable conditions of the last few days today's sunshine, warmth and waft of a breeze were welcome indeed - as well as being surprisingly productive. The day's really unexpected event was a short, sharp and spectacular movement of small shearwaters off the Bill an hour after dawn when c5000 Manx and c500 Balearics passed through in barely more than three quarters of an hour; such was the speed, volume and breadth of the movement - as well as the sheer surprise involved in as much as it developed without any warning and in the most benign of conditions - that it could only be quantified by rapid-fire sample counts but with Manx at consistently around 100 per minute and Balearics peaking at 67 in 5 minutes the overall estimates seem likely to be a pretty accurate reflection of the true numbers involved. With no more than a single Sooty Shearwater - along with 2 Arctic Skuas - tagging along it looks like large shearwaters have vacated local waters for the time being. Passage on the land was tame by comparison but interesting-enough nonetheless: Wheatear and Willow Warbler both topped out around the 30 mark at the Bill, where 6 Yellow Wagtails, and singles of Marsh Harrier, Merlin, Reed Warbler and Garden Warbler were amongst the back-ups; there was evidence from the mist-nets of Robin passage getting going as well. 

Although of only mildly esoteric interest, the Marsh Harrier over the Obs drew attention to how careful you have to be with interpreting photographs. When it was called we took the briefest of looks at it and then just blasted off a few photographs to have a look at later; it looked rather uniformly dark and we assumed it was bound to be a juvenile. In fact we kept assuming it was a juvenile even whilst looking through the photos until we got to the very last one of the 16 taken in which it had obviously pitched over a little bit and completely changed how the light fell on one of the wings - this revealed obvious moult going on in the primaries that clearly showed it couldn't be a juvenile (they won't be moulting their flight feathers until next year). On looking back more critically at the earlier photos it was possible to see, for example, the slight bulge in the secondaries where the new feathers are longer than the old feathers but this was really pretty subtle and easy to overlook when there was barely any colour-contrast visible between the old and new feathers. An interesting little lesson in how an apparently decent photograph - in fact 15 in this case! - isn't necessarily telling the whole story © Martin Cade: