Falsterbo (Lesser Whitethroats)

I've done a few things over the last few weeks but they all fit into one of two categories: not interesting enough to blog about or vaguely interesting but lacking enough time to follow them up with a thought-out post. Other than the couple of birds I handled at Portland back in March, I haven't done any ringing since I was in Sweden last year. I took advantage of the bank holiday weekend and reasonably cheap flights from Heathrow and decided to head back out to Falsterbo for a couple of days rest and relaxation (if you can call a 03:30 start resting!).

Species of the day at the lighthouse was Lesser Whitethroat, with 11 ringed (along with 11 Willow Warblers, a Blackcap, a Dunnock, a Chaffinch, a Linnet, and three Greenfinches). Ten of the Lesser Whitethroats proved to be second-years plus one adult (3+cy).


The first bird we caught, a second-year, looked at first glance to have undergone an extremely extensive pre-breeding moult with four of the secondaries on the right wing new and the entire tail fresh.


On closer inspections, it seems like the bird had lost and regrown the tail and some of the secondaries on the right wing. Just one secondary had been moulted on the left wing, and the rest of the moult in e.g. the coverts was quite normal.


The second bird was easier to age as a second-year; it had retained three juvenile greater coverts:


This bird had retained most of the tail. Actually in a damn good condition for a second-year Lesser Whitethroat!

It was nice to catch an adult (3+cy) to compare with the second-years. The wing if overall much fresher and darker, while the primary coverts have a subtle grey fringe (vs brown on second-year birds).


This second-year nicely demonstrates the rather narrow juvenile flight feathers, compared to the adults broader primaries and squarer secondaries:


The first bird in the blog post shows a fault bar across the tail, indicating simultaneous growth of the feather tract. As I've said before(!), it's often taken that this means the tail must be juvenile (since juveniles grow the entire feather tract simultaneously when they're in the nest). In the case of the first bird in this post, that's not the case since the tail has been entirely lost and regrown — it's equally as likely that that could happen to an adult as to a young bird, so it gives no worth for ageing. This second-year, however, does show a fault bar in the tail that is a result of the juvenile feathers being grown simultaneously:


More useful, and something that can be used as an ageing criteria, is the 'same' continuous fault bar across the wings. We can safely assume that this must have happened in the nest; an adult bird losing all of it's flight feathers at the same time surly can't stand much chance of survival! Beyond the fault bars, this bird shows the typical suite of plumage features associated with a second-year.


Finally, this second-year bird had its face encrusted with pollen; not from a local food source!