Wednesday 14 September 2016

Vis-mig

A nice bit of visible migration today: 1 Sandwich Tern (seen by the other guys), 600+ Barn Swallow, 60 House Martin, 22 Sand Martin, 72 Meadow Pipit, 7 Yellow Wagtail, 3 Buzzard, 2-3 Hobby, 2 Sparrowhawk, 1 Chaffinch, 5 Cormorant, 3 Wigeon dropped in over night and the Avocet was still around too. Also Green Sandpiper and 12 Snipe. 
 612 moving south, first along a line east of the hide and then the line shifted to the west. Abated between 1200 and 1300, peaking somewhere around 1100. Also Sand Martin and House Martins moving. The Sand Martins were mixed in with the Swallows but the House Martins were moving alone (mainly in one group). 
 5 Cormorant- migrating Cormorants are a local feature in August and September 
 Juvenile Hobby- one of two to three today, presumably moving through with the hirundines

 Two eclipse male and female Wigeon 
Interestingly the Coot were being territorial in the Indian Summer conditions
 Synoptic chart for today- a light south easterly air flow on the flanks of a very weak depression as yesterday's high pressure (below) becomes a bit wobbly. The warm and weak air flow conditions are obviously conducive to visible migration. High pressures with an easterly air flow are often associated with migration at the farmlands. The least productive weather conditions for autumn migration locally are keen westerly airflows or sitting on the flank of a high pressure with light west winds. The most productive are easterlies with frontal conditions (classic flights, falls and vis mig conditions), thunderstorms (good for drop outs), weak westerlies with low cloud (good for flights and falls) and high pressures systems with easterlies (moderate to strong can be very interesting). 
Sabine's Gull weather (yesterday's chart) (Photo by Roger Browne) 
Totally gripped. More grippage HERE

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