Horrid autumn- 11/9/17

11/09/17
06:30-08:20

Point- Just one Blackcap; persistent rain after dusk seems to have stopped most overnight migration higher up the country. One Willow Warbler in halfhearted song at the start of the causeway.

Viz mig- Four Meadow Pipit over the point, with another two over the shoreline. Single Sand Martin and 221 Swallow, all west.

Offshore- A young Marsh Harrier trying hard not to be harassed out over the estuary by a party of Crows. In addition to the large numbers around the Hill, clear that a distant Wallop Stone was full today; 240+ Grey Plover, 320+ Black-tailed Godwit, 40-ish Curlew among the easier to estimate.

When is Swallow movement actual migration? With Motney holding two roosts this year (Sewage Farm and Wildfowlers' reserve), how hard is it to discount numbers as roost dispersal?

My own rule of thumb, based on years of tape-luring Swallows for ringing. The vast majority will leave a roost pre-dawn, but birds can also mooch over the reedbed before deciding what to do. Some may loiter for an hour or so. As diurnal feeders, Swallows will be better off feeding when the insects are active. Unless a big movement day, when birds can continue through dawn 'til dusk, passage takes place for the first couple of hours. Steady movement, no feeding. Only when they reach the next suitable habitat do they pause to feed. Why ringers catch a lot of Swallow after 9, 10 o'clock in the morning this time of year; they don't respond to tape lures until ready to feed.

So, although I enjoyed clumps whizzing low over water and head height over the Hill, I was also sorry to see some of the birds were pausing and circuiting over the extensive cordgrass on Nor to feed; more than likely birds that will loiter around the estuary all day. Of my viz mig fig, about 40% looked like loiterers. Why so hard to interpret raw figures. One Swallow does not a migration movement make. Deep down I know I shouldn't think of Swallows as being in active migration flight mode unless I've had 3-400 whizz past me (and keep going) in those first couple of hours.

Harrison's 'Birds of Kent': "a map of the spring (red) and autumn (blue)
migrations of the Hirundinidae and Apus apus apus"
Based on records between 1905 -1951- now you know where I get it from.