Knot (Heysham) (1 February 2003)
A number of MRG members went to Heysham to join Morecambe Bay Wader Group in cannon-netting Knot Calidris canutus. After a number of interventions by one or more Peregrines Falco peregrinus, the last of which sent some 10,000 Knot away from the site, we ended up with 10,000 to play with, about one-quarter of whom are in the photo:
If anyone would like to count them, please let us know the answer! For those who haven't been there, this photo was taken from Jack Sheldon's van and the tarmac area in the foreground is the hardstanding of the helipad itself, used for the emergency helicopters to/ from the Irish Sea gas-rigs. The dog-walkers in the background are beyond the fenced area of the helipad.
The Oystercatchers Haematopus ostralegus mostly stayed along the edge or on the concrete seawall, and the Knot did not want to go beyond the large stones that had been set as net-markers but eventually some gentle pressure from John Wilson's car pushed the corner of the flock within catching range, and we caught 282. We were surprised to find that 278 of these Knot were 'new' and only four were already ringed, two from Morecambe Bay Wader Group and two British-ringed from elsewhere. Considering that we ringed 1,750 there five years ago, with one smaller catch since then, the proportion of retraps is remarkably low.
All but one were in winter plumage and looked grey, but one was a precocious individual showing how they get their new name of Red Knot:
If this catch was representative of the whole flock, Knot had a poor breeding season last year as there were few first-year birds. The photo below shows the characteristic feathers (coverts and tertials) with their dark subterminal band, generally brownish colour and frayed tips. Almost all of the white terminal colouring on each feather has been worn away - remember that the lighter-coloured parts of feathers are structurally weaker than darker-coloured bits: melanin gives the feathers strength. This bird, like all of the first-years, had undergone a fairly extensive post-juvenile moult involving its lesser and median coverts and some of the feathers between the tertials and the scapulars (I'm not sure what these are called). But notice that there are still some 'old' (juvenile) feathers on both sides of these new ones, including obviously the big feather immediately to the left of the three longish new ones.
We also noted that many of the 'adults' had two generations of contour feathers, roughly (but not exactly) corresponding to the same tracts of feathers that the first-years had. I wonder if this is indicative of a Euring age 7 (third calendar year) bird, but the BTO Wader Guide (A.J. Prater, J.H. Marchant and J. Vuorinen. Guide to the identification and ageing of Holarctic Waders. BTO Field Guide No. 17, 1977) is equivocal - it is now 25 years old and in my opinion a new edition is sorely needed, with updated knowledge and ideally with modern, in-the-hand photos.
An example of one of the adults is shown in the photo below, clearly showing its two generations of contour feathers. But if they have a partial post-juvenile moult, I wonder why they don't moult the tertials, which are the most exposed feathers and take the most bleaching and wear. Also, this bird seems to me to have a moult limit in its greater coverts, but it's the 'wrong way round' in passerine terms, with the newer four (?) feathers on the distal (outside, away from the body) side. Sorry that the feathers are a bit messed-up and not easy to count.
We still have quite a lot to learn.