Sunday 20 September 2020

Sunday 20th September

A little less overcast but otherwise similar conditions to yesterday, so with better attentiveness on the skies from dawn, 'vis-mig' was busy for many hours with a massive total of 595+ House Martin, the highest count here since Sep 2006 and only the 11th in excess of 500 birds. Also 192 Siskin was the highest count since Oct 2010 and, including yesterday's count, was only the 12th in excess of 100 birds here.  At 08:50, eight Avocet flew in off the sea, remained high as they circled the estuary corner, and perhaps unable to see anywhere suitable to land (it was nearing high tide) double-backed and flew out to sea; only the second record of the year.  Also overhead 47+ Swallow but larger non-estimated numbers apparently passed through offshore; 25 Meadow Pipit, 18 mixed 'alba' wagtail including at least two White Wagtail; 13 Grey Wagtail (best count here for six years), three Grey Heron high in off (flew west), three Lesser Black-backed Gull flew south, two Yellow Wagtail, two Lesser Redpoll and a Buzzard.

This type of birding is not easy and is advisably done with company. A few rough calculations to illustrate this - if someone has 20:20 vision and if birds were similar in perceptibility as distinguishing letters from each other, let's say by comparison to a Snellen eye chart, then given the wingspan of things like Siskin, Meadow Pipit and House Martin, should be visible to the unaided eye at distances of c.150 to c.215 metres away, but if features on such birds were a tenth of those sizes, then 10x binoculars would be needed to ID them, notwithstanding difficulties of lighting, shaking and, of course, the bird is flying (not the sorts of challenges one experiences during a standard eye test!). Whilst human eyesight has impressive 180° vertical x 135° horizontal FOV (field of view), some binoculars have only approximately 6°, so that's a lot of scanning around to do to find birds that are more distant, and to identify them.  And furthermore, if a bird was identifiable at 150 metres distance and leisurely flew by at 20 mph, one may still only have c.25 seconds to spot it, but this reduces to only 16 seconds if earnest movement approached 30 mph, and often a lot less time than that as birds are found already part way through and bins will be needed to get those crucial features.  Competence in identifying bird flight calls evens the odds and many of the individuals and flocks passing through were first picked up this way today.  

Little was supported in the bushes with counts of just three Chiffchaff and single Blackcap and Whitethroat. In open areas, there was a minimum of 55 Goldfinch since small parties continued to arrive and leave; 40+ Linnet, nine Greenfinch and three Wheatear. Later in the afternoon a tit flock moved through that contained most of the 16 Long-tailed Tit, 13 Blue Tit and five Great Tit.  Regularly reported popular residents were nine Stonechat, three Cirl Bunting, two Great Spotted Woodpecker and two Bullfinch

The high tide was covered throughout and highlights were three Pale-bellied Brent Goose with five Dark-bellied Goose and another three Dark-bellied flew in off later. An adult drake Eider snoozed on Finger Point and later flew out to sea; perhaps the same as yesterday's imm/♀ was close offshore.  The only counts actually gathered were 262 Wigeon, 190 Dunlin, c.30 Ringed Plover, 25 Cormorant, 24 Great Black-backed Gull, ten Sandwich Tern, four Turnstone; all the usual species were present.  Beach depth had visibly eroded since last night's huge tide and along the shoreline were 34 Sanderling (29 juvs, 5 moulting adults).

Only five Common Scoter and a solitary Gannet offshore.  On the Main Pond, ten Teal (more in the estuary) early morning only; four Moorhen and a Kingfisher.  The main viewing gap, repeatedly re-blocked by TDC to obscure viewing of this attractive vista since November 2019 (!) was re-opened a few days ago to allow access onto a screened viewing platform.

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