An interesting discussion, and there are other
predators involved too, like the bigger Gulls. See photo below -
the Swifts were nesting beneath the Roman tiles and were
literally picked off as they emerged. (The photo is copyright
and from Jerry Firth.) Of course, these Yellow legged Gulls were
not present in Rome until very modern times, and the same
applies to Herring Gulls here in the UK.Formerly maritime, they
are now commonly urban. Nest colony size - a very difficult one
to work out as many colonies in Southern Europe are immense, and
there are arguments that a great crowd of birds in the sky makes
it very difficult for a predator like a Peregrine to "lock on"
to its target and pursue it amidst other fast flying birds -
hence the value of moving in a crowd, and also why Peregrines
often pick on the last bird in the flock as it goes by. A lone
bird has hardly any chance against a predator, two birds each
have a 50% chance of survival or better, but in flock of 100 you
have only a 1% chance of being caught. More observations needed!
Best wishes, Edward

"martin....@sky.com" <martin....@sky.com>: Sep 28 12:44PM
Hi All,At the Gledhow colony in Leeds, we've had similar experiences to Mark in Bristol.The colony consists of a concentration of boxes on my house, with around 22 pairs and then another 18 pairs spread out over houses on the rest of my street. The overall numbers of pairs increased this year from 33 to 40, but the colony was subject to visits from a Sparrowhawk and at least 6 adults were predated.In the part fully monitored with cameras, 18 pairs made breeding attempts, laying 47 eggs. 5 eggs were ejected, 5 failed to hatch and 3 chicks died. 31 chicks fledged here and 3 more fledged after care from Linda Jenkinson at the Leeds Swifts sanctuary.With 34 fledging from 18 attempts, the productivity is 1.9 chicks.However, in one of the breeding attempts, both eggs were deliberately and strangely ejected after 16 days of incubation, so disregarding that attempt gives a productivity of 2.0 chicks. It was a tough year to witness, but overall the colony grew and spread to more houses in the street.I witnessed one Sparrowhawk attack. The Hawk was on the roof and took a Swift as it was leaving a nest box, as it started to climb after flying downwards and away from the box. Luckily, the Hawk landed with the Swift in a nearby drive and I was able to startle it into releasing the Swift, which thankfully, after rest, was ok.Best wishes,Martin, Leeds Swifts.
On Wednesday, 27 September 2023 at 08:18:15 BST, 'Mike Priaulx' via swiftslocalnetwork <swiftsloc...@googlegroups.com> wrote:
Hi Mark/ all,
Regarding colony size and predators, this is an interesting point and has come up in our Swifts & Planning Group - the post was Swift Colonies and Predators on 23/08/23,
which stated:
"One point raised at the recent Swifts & Planning Group meeting was that some large colonies are attracting predators and it's a factor that should be borne in mind when designing installations.
Whilst some level of predation is normal we aren't really helping if we inadvertantly give predators an easy lunch.
Swift bricks and boxes are mostly predator-proof but the birds need to access the boxes and it's at this point they are vulnerable to a range of avian predators: Hobby being the classic species we all know about but there are incidences of Kestrel, Peregrine, Sparrowhawk and even Magpies being a potential threat.
Avoiding obvious perches for predators (both above and below the colony), and excessive concentrations of swift bricks & boxes, are the basic precautions.
There may be more specific tips that people have from experience?
Perhaps some sort of design guide could be a long-term aim?"
Thanks to all so far who have posted yearly summaries so far, very interesting to see the variation around the UK.
Thanks,
Mike
Member of SLN Swifts & Planning Group
Bristol Swifts <bristo...@gmail.com>: Sep 26 02:58PM +0100
Hi All
Not such a good year here in Bristol re; chick fatalities...
ps. Another topic for discussion for another day is can you have too many
swifts nesting in one location? We have almost 20 pairs and they make quite
a bit of noise especially in the evening. Their activity definitely hasn't
gone noticed by the local predators. The last couple of years we've been
targeted by sparrowhawks who have worked out how to ambush the swifts as
they return. Maybe having fewer pairs would make their nest sites less
conspicuous. Maybe there's an optimum number which once passed is
counter-productive to the overall health of the colony.
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Mike Priaulx <michael...@yahoo.com>: Sep 28 01:44PM +0100
Hi all, the State of (UK) Nature report has been released today. In summary, it could be better, although some glimmers of hope due to the hard work of people like us. Here's the report:
https://stateofnature.org.uk/
There are some useful infographics if you don't have time to read the report:
https://stateofnature.org.uk/infographics/
This report always seems to overlook urban wildlife, but a reminder that does get some coverage in the State of the Urban Environment report (here is the last issue of it):
https://www.gov.uk/government/publications/state-of-the-environment/the-state-of-the-environment-the-urban-environment
There's been a demonstration at DEFRA today:
https://twitter.com/ChrisGPackham/status/1707310583530291234
Here's how you can help:
https://stateofnature.org.uk/get-involved/
All the best,
Mike
Member of SLN Swifts & Planning Group
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My short experience with boxes is that magpies are quite interested while the local gulls haven’t bothered with the boxes on my house. And after 6 years I finally have sparrows which I don’t mind as they signpost the nest sites to other birds, hopefully swifts!
I think it is better to have boxes up than no boxes, I’m sure insects will use them if birds don’t initially use them.
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Hi all
You can read our latest blog about the Hospital of St Cross, Winchester here https://www.hampshireswifts.co.uk/post/hospital-of-st-cross-update-1?utm_campaign=a7d0ced0-95bb-4656-80b7-f4fec2e5475f&utm_source=so&utm_medium=mail&cid=f6871a71-8312-4eb7-a899-3b07dde87ba9
Cheers
Tim Norriss
Hampshire Swifts