I joined David Norman for some early morning mist-netting at Oxmoor LNR — the site should be dripping with breeding warblers and, after the recent dismal weather, we were expecting to catch large numbers as they took advantage of the dry spell — the reality couldn't have been further from the truth; in the first net round we caught just a single bird, a Robin.
The bird is in heavy moult, growing a chunk of inner primaries and having dropped all of the tail feathers almost all at once. This photo was taken before dawn, so it seems that my new lens copes well in low light.
Sunrise behind the Eddie Stobart warehouse...
Things eventually started to pick up on the third net-round. We caught some juvenile Sedge Warblers, the first juvenile Acrocephalus warblers of the year — a minor success in what seems to be a dismal year for the species.
We also caught two of these beauties:
female left, male right — nicely illustrating the difference between blue-green and green-blue.
In actual fact, compared to the second individual, the orange on the bill of the first isn't *that* extensive. Here's the bird we sexed as a female to compare:
A male Bullfinch added yet more colour to the ringing
It's a second-year that's retained two juvenile greater coverts; and, of course, the obvious biscuity-tipped carpal covert.
This 2cy male Common Whitethroat had moulted its outer six primaries and inner four secondaries some time over the winter.
Back to Sedge Warblers, adults this time. We caught several female warblers with active brood-patches indicating that they were or had just finished incubating eggs; one of these birds had been recorded as being at the same stage when she was first ringed but, with not enough time between then and now to have completed rearing a first brood, it seems that she is trying again following failure the first time around. It was interesting to note the difference in wear between individuals. This individuals is rather fresh looking:
While this individual is considerably more worn:
Sedge Warblers are reported to follow two or three moult strategies. Some birds moult as soon as they arrive in Africa, then have a partial pre-breeding moult before spring migration — presumably that's what we're seeing with the second bird; the worn primaries suggest an early-winter moult while the apparently fresher-looking feathers on the mantle may the the product of a pre-breeding moult, though the worn tertials suggest that any pre-breeding moult was limited to the body. Other birds wait until they have reached their southern African wintering grounds before moulting; these birds do not have a pre-breeding moult — with fresh primaries, tertials and body feathers, that is presumably the moult strategy the first bird has followed. There is an intermediate strategy with some birds starting moult on arrival in Africa before suspending and completing once they arrive on southern African wintering grounds. A topic I've never really looked into much before and interesting to think that two birds from the same site could potentially have undergone such different wintering strategies. I wonder why? Definitely something to take a closer look at next time I handle some more Sedge Warblers!
This Reed Warbler was a known-age retrap, originally ringed several years ago:
Finally, this male Goldfinch was also a retrap. It had moulted all of the greater coverts and the central two pairs of tail feathers during its post-juvenile moult.
So, all-in-all I'm pretty pleased with my new lens. It's smaller and a lot lighter than my previous lens but still seems to do an equally good job, and the size and weight should make it a lot easier for transporting around — especially when I'm trying to stuff my life into a backpack ready to take the next EasyJet flight!