Over Allden's

Two exciting events have occurred during the last week, both involving species migrating over Allden’s Hill, as the wheels of spring begin to turn. On Sunday I was treated to a notable movement of my favourite vis-mig species: Meadow Pipit. This was somewhat eclipsed, however, by the first decent noc-mig session of the year on Monday night that delivered not one, not two, but three Common Scoter flocks!

Meadow Pipit, Allden's Hill, 17/3/2019.

I’ll start with the Mipits. In very windy conditions on Saturday there was a marked arrival of the species in-off the Channel, all along the south coast. I figured many would then hunker down, before moving when the winds dropped (significantly) in the evening and overnight. This turned out to be the case and several of those wonderful squeaks could be heard as soon as I opened the car door atop Allden’s about quarter of an hour before sunrise.

In one hour I logged 165, with the largest single flock some 18. If I was better prepared I’d have stationed myself on Broomy Down where I would have picked up more with the wider field of view. All birds were pretty low, all north/north-west, and movement had virtually ground to a halt about half an hour after sunrise. I’ve harped on about it a few times before but Mipit migration, particularly in late March, is my absolute favourite when it comes to vis-mig. At Thorncombe Street at least, it’s the first real sign that spring is here. 165 is my second-best spring count and came about a week or two earlier than usual. Perhaps I’ll be treated to another push later in the month.

With the battering westerlies of the past few weeks preventing any nocturnal sound recording, I wasn’t the only one pleased when they finally stopped at the end of the weekend. On Monday night, a gentle south-westerly with low cloud (and even some brief and light rain) felt ideal. It turned out to be a relatively busy night, highlighted by three separate flocks of Common Scoter: at least two at 20:59, at least six at 23:36 and another two or more at 04:35.

Common Scoter sonogram, from 18/3/2019.

The concept that this species hasn’t just passed over here/inland once or twice, but indeed does so fairly consistently and on a broad level, still blows my mind (also bear in mind females don't call, and all drakes over two years old produce audible wingbeats, so what we're hearing is an absolute fraction of the birds moving). The spaced-out timings of these three flocks suggest the departure was on a very broad level that evening, probably throughout the English Channel and right the way down the French Atlantic coast. If Common Scoter fly 92 km per hour (Berman & Donner, 1964), and if the ones over Thorncombe Street followed the Arun north (which is quite easily not the case), then the first group would have left the Channel about an hour after sundown. On that basis, the latter flocks would have departed from further down the French coast.

This is all highly speculative, though, and Matt having a flock over Pulborough at 21:50 doesn’t add much proof to the Arun theory. Perhaps the flocks don’t follow any topography and simply plan to fly so high that it doesn’t matter, with cloud/precipitation forcing them low? This is quite possibly the case, and with such ideal conditions after such a windy period I bet loads of seabirds and ducks chose to move that night; I'm sure there would have been an inland 'fall' of bits had there been any morning fog. Over the next few years it’ll be fascinating to find out if Common Scoter isn’t a rare Surrey bird, but indeed a regular, annual spring migrant at night. Mid-March to mid-April is doubtless the best time, with associated weather needed, but I would even suggest they are twitchable … something I might consider, especially as the first group moved over at a perfectly reasonable hour.

Mute Swan, Bonhurst Farm (mega extralimital record!), 18/3/2019.

It was a fairly busy night, with three Moorhens, nine Redwings and singles of Coot and Mandarin logged. There was also a huge flock of Canada Geese and a presumably disturbed local Carrion Crow, along with three owl species. A great way to kick off the year. A clip of the first scoter flock can be heard here. A review of my first year of noc-mig will feature in the upcoming 2018 Thorncombe Street Area Report, along with a focus on Common Scoter and Ortolan Bunting.