Heavy Overhead passage today. (1 Viewer)

Jane Turner

Well-known member

• Oct 29, 2012

• #1

Just back from a trip to Red Rocks where I have seen more migrating passerines in an hour than I'd guess for the rest of the year.

Got to do some work for the rest of today, but here are a couple of shots. The first flock is a tiny part of a Starling flock that reached from north of the point, out of sight over West Kirby.

I've no idea how many... I've guessed 18k.... but on reflection, had this flock be waders, then there would have been 30-40k in the one flock. I should have a better idea of numbers after I've estimated the photo.

 

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PYRTLE

Old Berkshire Boy

• Oct 29, 2012

• #2

C'mon Jane, stop teasing and attach the photos,ta. Still regular movement down here of starlings, thrushes and blackbirds - no joy (yet) on squeezing out a rouzel in the parish.

 

Jane Turner

Well-known member

• Oct 29, 2012

• #3

Sh!t,.... could be out by an order of magnitude.... a flock 20-30 birds thick for 2km! And there were two flocks of this size, the restwere just in the 100-1000 range!

 

Jane Turner

Well-known member

• Oct 29, 2012

• #4

I'm about to count the photo....but using a photo taken at the same distance from the same place at the same magnification, I can estimate that this is about 10% of the flock by angle.

I might also be able to work out the size of the flock by its average width and density of the flock, ie the space between them based on the wing span of a Starling!

I could see the flock went as far as half way down the Marine Lake (which is actually 5km)

 

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Jane Turner

Well-known member

• Oct 29, 2012

• #5

7-800 is my guess on the numbers in the above photo...

20k for the flock?

 

rosbifs

PutAin STOP

• Oct 29, 2012

• #6

oh to be a peregrine - and a fat one....

 

Jane Turner

Well-known member

• Oct 31, 2012

• #7

750 is looking like quite a good guess for the numbers in the photo... c250 a square section though the flock. Just need to work out how many times wider the flock was now.... though I got my scale wrong before - its 2.5km since I measured a 500m scale

 

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Last edited: Oct 31, 2012

Jane Turner

Well-known member

• Oct 31, 2012

• #8

The only internal measure that I have in my photos are the starlings themselves.

I guestimate that you could fit 80x wing span (40cm) wide starlings wide would make my big squares about 3.2m (250 birds) The flock was more straggly further south, so lets pessimistically drop the average number of birds per square to half of the end I photographed, ie 125 birds per square

1 could fit 180 squares into 2.5km

Which would be 22,500 birds for the biggest of the three immense flocks. (There was another after I left that stretched most the way to WK)

That would be about 2/3 of the density of a Dunlin flock...which feels about right

 

Last edited: Oct 31, 2012