Dispersal of Common Swift - UK (1 Viewer)

Andy Adcock · Jul 29, 2019

Over the years, I've noted that in Nottingham, most Common Swifts have gone by the second week in August yet, when I'm in St Petersburg, Russia, they are evident in to late August at least.

St Petersburg is a lot further North than Nottingham so why do birds linger there longer? Is it just that the Nottingham birds move to congregate on the coast before migration which the Russian birds don't need to do?

KenM · Jul 29, 2019

andyadcock said:
Over the years, I've noted that in Nottingham, most Common Swifts have gone by the second week in August yet, when I'm in St Petersburg, Russia, they are evident in to late August at least.

St Petersburg is a lot further North than Nottingham so why do birds linger there longer? Is it just that the Nottingham birds move to congregate on the coast before migration which the Russian birds don't need to do?

Might the air temperature be higher Aug.end of in St.Petersburg at that time than in the UK, which may have cooled somewhat by that date. (ie more flying invertebrates) in the higher temps?

Cheers

halftwo · Jul 29, 2019

When do they arrive in St. Petersburgh?

Nutcracker · Jul 29, 2019

They clear out as soon as the young fledge. So presumably the breeding season in St P starts and finishes ~2 weeks later - I'd guess the start of spring is equally later in St P.

Andy Adcock · Jul 31, 2019

halftwo said:
When do they arrive in St. Petersburgh?

That's a good question, I'm often not there when they arrive so can't answer?

Andy Adcock · Jul 31, 2019

KenM said:
Might the air temperature be higher Aug.end of in St.Petersburg at that time than in the UK, which may have cooled somewhat by that date. (ie more flying invertebrates) in the higher temps?

Cheers

I doubt it Ken, on the same latitude as Shetland!

KenM · Jul 31, 2019

andyadcock said:
I doubt it Ken, on the same latitude as Shetland!

We know that the continental land mass enjoys more extreme temps than “Island’ UK andy, thus it would be interesting to know if Summer by “mean” temperature arrives earlier and or stays later than it does in Blighty.

I have to assume rightly or wrongly, that their is a “mean” arrival/departure difference for Shetland Swifts and say London Swifts, particularly as the London Swifts are concentrated en masse by the various reservoir groups?

Remembering that perhaps three or four days at either end might make a difference, that was my thought...and fwiw I assume other European countries would have a “mean” arrival and departure date for this species, any differences might be of interest regarding their North/South range within?

Cheers

Britseye · Jul 31, 2019

12:40 31/07 Common Swift East Yorkshire Spurn YWT 11:00
2,842 flew south past Numpties

Andy Adcock · Jul 31, 2019

Britseye said:
12:40 31/07 Common Swift East Yorkshire Spurn YWT 11:00
2,842 flew south past Numpties

Is that an unusually large number for the time?

stevo · Jul 31, 2019

Or the further south that they nest,the longer they can stay.Due to a shorter migration?

Xenospiza · Jul 31, 2019

andyadcock said:
Is that an unusually large number for the time?

Would seem so, hourly averages are highest in early July: https://trektellen.nl/species/graph/5/285/249/0?language=english&g=&l=&k=&jaar2=&jaar3=

Xenospiza · Jul 31, 2019

Most birds cleared off this weekend in the Ruhr Area, Germany. Just a few individuals left where there used to be flocks.
The start of the breeding season sounds like a good explanation to me.
For example (also based on trektellen.nl), the peak of migration at Breskens (NL) is the first week of May, whereas in Latvia it appears to be the third/fourth week of May.

Hauksen · Jul 31, 2019

Hi,

Xenospiza said:
Most birds cleared off this weekend in the Ruhr Area, Germany. Just a few individuals left where there used to be flocks.

The 4-nest micro-colony in front of my window (near Hamburg) obviously has finished breeding, but maybe 40% of the neighbourhood birds are still around as they are having screaming parties pointing out the nests.

(I always wonder of the young take part in these parties, but from I've recently read, it seems they don't.)

I've tried to make sense of the ornitho.de statistics, but they might be too coarse to show the migration South.

Here's the overview for all of Germany for 2018:

Screenshot_2019-07-31 - www ornitho de.jpg

Regards,

Henning

Xenospiza · Jul 31, 2019

Hauksen said:
Hi,

The 4-nest micro-colony in front of my window (near Hamburg) obviously has finished breeding, but maybe 40% of the neighbourhood birds are still around as they are having screaming parties pointing out the nests.

I've tried to make sense of the ornitho.de statistics, but they might be too coarse to show the migration South.

If the other contributors are anything like me, they are much more likely to report a Swift in August than in June/July.

Hamburg/Ruhr Area is not Nottingham/St Peterburg, but it fits to the pattern!

Hauksen · Jul 31, 2019

Hi,

Xenospiza said:
If the other contributors are anything like me, they are much more likely to report a Swift in August than in June/July.

You're right, and I think I'm not all that different

The overview graph I posted is based on the maximum group size of swifts per square of the "TK25" topographical map, per 10 day period.

That should be pretty resilient against irregular reporting, except perhaps in very sparsely populated parts of the country.

Regards,

Henning

KenM · Aug 1, 2019

Xenospiza said:
Most birds cleared off this weekend in the Ruhr Area, Germany. Just a few individuals left where there used to be flocks.
The start of the breeding season sounds like a good explanation to me.
For example (also based on trektellen.nl), the peak of migration at Breskens (NL) is the first week of May, whereas in Latvia it appears to be the third/fourth week of May.

Does that mean that the further East that one travels at this time, the “mean” temps are lower, hence the earlier arrival times to the West?

Cheers

Andy Adcock · Aug 1, 2019

KenM said:
Does that mean that the further East that one travels at this time, the “mean” temps are lower, hence the earlier arrival times to the West?

Cheers

Well I can tell you that generally, St Petersburg's spring is almost a month behind Nottingham's.

I guess they breed later due to food availability so leave later?

KenM · Aug 1, 2019

andyadcock said:
Well I can tell you that generally, St Petersburg's spring is almost a month behind Nottingham's.

I guess they breed later due to food availability so leave later?

Kinda makes sense....:t:

Britseye · Aug 1, 2019

Thirty-one thousand three hundred and fifty Swifts passed south Gibraltar Point, Lincs yesterday:eek!:

KenM · Aug 1, 2019

Britseye said:
Thirty-one thousand three hundred and fifty Swifts passed south Gibraltar Point, Lincs yesterday:eek!:

Probably goes some way explaining just the two seen today over the house.

......and now c15. :eek!:

Dispersal of Common Swift - UK (1 Viewer)

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