Re: [SLN] Digest for swiftslocalnetwork@googlegroups.com - 8 updates in 4 topics

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John Denis Le Seve

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Jun 10, 2026, 8:40:15 AM (3 days ago) Jun 10
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Good news!
St Peter's Hospital (Maldon, Essex) renovation team are unanimously agreed that we should help the nesting swifts. 
They are going to remove the scaffolding before mid July.  (At present I don't think it is impeding access).
They will not block the holes. 
Furthermore they are happy to consider putting up more swift boxes.
On Friday I'm meeting the project manager and we will have a close look at the nest holes and look at how we can install more swift boxes.
Isnt that great!
John

From: swiftsloc...@googlegroups.com <swiftsloc...@googlegroups.com>
Sent: 10 June 2026 07:58
To: Digest recipients <swiftsloc...@googlegroups.com>
Subject: [SLN] Digest for swiftsloc...@googlegroups.com - 8 updates in 4 topics
 
<an...@tali.me.uk>: Jun 09 08:32AM +0100

Much of the rationale for demonising Crataerina seems to be based on its less than appealing appearance and unfortunate dependence upon Swift blood to survive.
 

 
But what are the facts? Review of the literature suggests that there is no evidence that infestation with Crataerina has any impact on the breeding success of Swifts. This seems at odds with common sense or “logic” which would surely dictate that any parasite which removes blood must be having a negative impact on survival?
 

 
However, we know Swifts and Crataerina must have evolved together over millions of years and so, on a population level, given that Swifts are still with us as a species, they can clearly cope with some blood loss. On the other hand, at the nest level, on occasion, perhaps an overwhelming Crataerina infestation can either be the consequence, or the cause, of chick weakness and death?
 

 
It’s worth bearing in mind that wild birds host an astonishing array of parasites. I have no information for Swifts but swallows, for example, have been found to host “..at least 16 species of helminths, 8 species of mites, 3 species of louseflies, 7 species of fleas, 1 species of feather louse and 11 species of protozoan blood parasites” (this is a quote from Ian Newton’s book Bird Populations) so leaping to conclusions about the one parasite which is actually visible may be unwise.
 

 
Returning to the statement that Crataerina has not been shown to have any impact on swift survival, might it be worth someones time to review the publications which were used to come to that conclusion? Did they have control nests (i.e. crataerina-free?) against which breeding success in infested nests was compared, or did they show that the level of infestation was unrelated to nesting success? Either way, surely now we can look at this in more detail?
 

 
Every year thousands of Crataerina-free swift nests are installed across the country, many with cameras. According to the literature the Crataerina lifecycle takes place entirely at the level of the nest site. Swifts leave for migration free of Crataerina and arrive back free of Crataerina, so the only way a nest site can become exposed to Crataerina is if a returning swift happens to visit an infested nest en route. Although recent work suggests this is more likely than was originally thought to be the case, you’d think that new site sites would only gradually be infested with the parasite, allowing us the opportunity to compare breeding success in Crat-free nests with that in infested nests. This would need a fair number of nests to obtain a meaningful conclusion but having the equivalent of a placebo-controlled trial to assess the impact of Crataerina would make for an interesting piece of research.
 

 
Andy Broadhurst
 

 
 
 

 
Member of SLN Swifts & Planning Group
 

 
abroa...@derbyshireswiftconservation.org
 
07941 349002
 

 
Derbyshire Swift Conservation is a Charitable Incorporated Organisation.
 
Registered Charity Number 1206439
 

 
From: swiftsloc...@googlegroups.com <swiftsloc...@googlegroups.com> On Behalf Of Hythe Scream
Sent: 09 June 2026 01:49
To: swiftslocalnetwork <swiftsloc...@googlegroups.com>
Subject: Re: [SLN] Crataerina - a problem?
 

 
Thanks for the links Dick. I'll take a look, but I can't get experimental data out of these without cooperation from the owners.
 
Thats why we have the best opportunity within our group, where the issue was originally mentioned and clearly upsets many of us.
 
I am happy to facilitate everything and report on the outcomes, but I need data from those with problem boxes, and the ability for the conditions to be changed and monitored for a couple of years. If no one comes forward, then we lose our chance to help these lovely birds. If anyone reads this message, please read my previous one too, and message me privately if you want to take part. You can use a different email address to the one you use here if you wish (send me a message to hythe...@gmail.com <mailto:hythescream@gmail.com> Put "Crataerina survey" in the subject line.) I will not divulge your name or location, I will just speak with you individually and collate the results anonymously. If you know anyone else outside of this group that would like to take part, then talk to them and show them my previous email if you are able to.
 
To take part in this important research, you need to have boxes where they are monitored with a camera, currently experience flat fly infestation, and where you are able to remove the box for treatment during the off-season.
 

 
I know that many of you will be worried about the swifts under your control and the affects that this parasite has on their general wellbeing. It's horrible to watch, so let's help them to lead happier, and more comfortable lives, and to be more productive towards our goals to slow their demise in the UK.
 

 
Thank you
 
Ron
 

 
On Monday, 8 June 2026 at 12:29:35 UTC+1 Dick Newell wrote:
 
Well Ron,
 
If you want to study this issue, there are plenty of Swift webcams here: https://gierzwaluw.website/webcams.html
 
Let us know when you find one with a big infestation.
 
Dick
 

 
On Mon, 8 Jun 2026 at 12:18, Hythe Scream <hythe...@gmail.com <mailto:hythe...@gmail.com> > wrote:
 
Ok folks, let's deal with this sensibly. Some of you are getting confused.
 

 
I'll start again with the problem, the evidence, the cure and the benefits.
 

 
The problem.
 
From camera footage, it's clear that the birds visually suffer from this infection. That clearly upsets them, and also upsets me to watch any animal being uncomfortable. There is some suggestion that they will leave their nests even. But onto the physical effects, it's got to affect their production. Maybe not every time, but if the weather is bad, food supply a little low, and you have the straw that breaks the camel's back. No one knows how many young swifts perish from this in their first flight to Africa. The motality rate is high, and somewhere around 50%. They might struggle to get there for all we know because of this problem. Until they can shrug off the fly, they will be weakened and struggle to get enough food.
 
The evidence.
 
Firstly, all known animals that lose blood will fail to perform at their best. This can be demonstrated by taking half a cup of blood off you each day (the swift equivalent scaled up) and then sending you down to Tesco's to get me some food 20 times a day. I am guessing that it will soon have an effect on my food quantity! You can observe those with anaemia to see how they suffer. In the real but strange world of cycling, riders used to ride in the mountains to improve their blood, then take a few pints to pop into the freezer. On race day, they would replace their blood with the 5* frozen blood variety to win their races. Blood quality and quantity is important. Now onto blood sucking parasites. Research has suggested that there are ZERO known cases in ANY creature on this earth where blood sucking insects give any benefits back. A parasite and symbiosis are two completely unrelated things. Most blood suckers will cause blood loss and even spread disease. Human equivalents of that are Malaria, Dengue fever, Lymes disease, Zika, Trench fever, the Plague and many more. They all, without fail, disable people. The massive loss of swift blood is bad enough, but they may even have a disease that's not yet been discovered. It could even be part of their recent demise. A disease can be newer than 50 million years old. Take HIV as a recent example. Lots of diseases spread across species these days, and for all we know, a "relatively harmless" fly could now be spreading blood borne diseases too. They might kill the birds after 6 months! Think about that for a minute!! Reading the swift article, the evidence quality around this fly is very sketchy to say the least.
 
The cure
 
We can't cure this disease, that's clear. But we are in control of their population increase in the UK, and we want the best for our swifts. When I used the word "disinfect", that doesn't mean hoovering out their nest or using bleach!! I explained that the best way is to put the box into a bag, and then into the freezer for 48 hours. Alternatively, you can hand pick the pupae. Obviously, many boxes are no longer accessible. But we have a plan. In my own case, I don't yet have any birds in my boxes, but I designed them to be taken off easily so I can do this when it's time. I suggest that when it's possible, you install boxes in such a way that they can be maintained. You might need to remove dead chicks or unhatched eggs as well. Many boxes are designed with removable fronts. But it's better to take them down if possible. (As a side issue, I'm working on a box design that can be removed and put back up from the ground. This would revolutionise this issue)
 
The nest itself should not be damaged by sweeping it all out. As mentioned, this is important. I pre-feather my new nest cups before installation anyway.
 
The benefits
 
Firstly, the swifts will live comfortably, and be able to get on with the job at hand. We will know that they are not suffering, even if we can't watch this on camera. Any marginal gains can have a massive impact on their population's plight, although we cant measure this.
 
The science
 
If there is anyone with cameras and known infections, would they please raise their hand if they are able to help with some citizen science. The chances of a PHD being conducted in this day and age are near to zero, so it's down to people like us. We are the knowledgeable custodians. We need boxes with infections and cameras. We need someone to hand pick, someone to freeze, and someone to monitor a control box. The more participants the better. I'm happy to design an experiment and collate the data.
 
As the original OP stated, watching them suffer is horrible. No one wants to see this. It's possible to stop it for any birds in your custody. That is a positive enough reason to do something about it.
 
Without real scientific studies, it's easy to dismiss this problem, but using logic and experience of other animals including humans, there's a good hypothesis to proceed with some remedial action. Every little helps as you say.
 

 
Thanks for listening to me repeating myself ;-)
 
Ron
 

 
On Mon, 8 Jun 2026 at 10:57, Tony Croft <the.cro...@gmail.com <mailto:the.cro...@gmail.com> > wrote:
 
Nest provision more important than the effect of the parasite I think based on what Dick is saying...still don't like seeing them there though!
 
 
Best Regards
Tony
 

 
On Mon, 8 Jun 2026, 10:08 'Jean Stafford-Baker' via swiftslocalnetwork, <swiftsloc...@googlegroups.com <mailto:swiftsloc...@googlegroups.com> > wrote:
 
Thanks for the reassurance Dick. We've seen Crataerina for the first time this year. It's good to know they won't negativity impact the Swifts.
 
We have no intention of touching the nest. We waited 8 years for our Swifts to choose our box & wouldn't interfere in that way.
 

 
Jean (Norwich)
 
Yahoo Mail: Search, organise, conquer <https://mail.onelink.me/107872968?pid=nativeplacement&c=US_Acquisition_YMktg_315_SearchOrgConquer_EmailSignature&af_sub1=Acquisition&af_sub2=US_YMktg&af_sub3=&af_sub4=100002039&af_sub5=C01_Email_Static_&af_ios_store_cpp=0c38e4b0-a27e-40f9-a211-f4e2de32ab91&af_android_url=https://play.google.com/store/apps/details?id=com.yahoo.mobile.client.android.mail&listing=search_organize_conquer>
 

 
On Mon, 8 Jun 2026 at 9:18 am, Dick Newell
 
<dick....@gmail.com <mailto:dick....@gmail.com> > wrote:
 
For those of you who still think it is desirable to clean out a nest box at the end of the season, I can say that if you remove the nest, that is a terrible idea. The Oxford museum did this at one time, with negative effects on breeding success. They stopped doing it.
 

 
We proved conclusively that Swifts occupy nest boxes with a nest form much more quickly than nest boxes without. They are more likely to breed, as they don't have to first build a nest.
 

 
Preserving their nests intact is hugely more important than removing a parasite that has been proven to have no negative effects.
 

 
Besides, climbing a ladder to take down a nest box to put it in the freezer, then climbing the ladder again to put it back up, is twice as much ladder-climbing as putting up a box in the first place. Why not put up 2 more nest boxes for the same amount of ladder-climbing?
 

 
And as for chucking chemicals into the box, what are we thinking of?
 

 
What am I missing?
 
Dick
 

 
On Mon, 8 Jun 2026, 08:24 Tony Croft, <the.cro...@gmail.com <mailto:the.cro...@gmail.com> > wrote:
 
Good thinking....
 

 
We really don't know what's best...
 

 
Just wonder if we "disinfect" the nest box would thus put off a returning pair...?
 

 
We could try various practices in different colonies if that were possible? Perhaps interest someone in doing / orgaising a controlled trial across a few sites for a pHD or similar?
 

 
Just a thought....
 

 
To clean and sterilise or not to?
 

 
 
Best Regards
Tony
 

 
On Sun, 7 Jun 2026, 22:56 Hythe Scream, <hythe...@gmail.com <mailto:hythe...@gmail.com> > wrote:
 
Thanks for the research link Audrey. I read it!
 
There's no real evidence either way, but I would say that's because proper studies haven't or can't be carried out accurately enough to have a clear outcome.
 
Some consensus is the idea that there's a hidden symbiotic arrangement. That's possible, but there's no evidence at all to suggest this. There are two types of parasites, some like the "cleaner fish" do a good job for the host, but some just live off the host and survive in their own balance by not killing them. There's no rule about being symbiotic. Take flu as a virus example. There's nothing symbiotic about that! From what I have read, and understand about blood loss and irritation, there's no doubt that swifts do NOT benefit from this parasite at all, and it could easily cause them to move out of a perfectly good nest, or be weakened detrimentally to their output of fit offspring. I would advise anyone that has the capacity to disinfect their boxes to do so. It's down to "marginal gains", and the swift population needs every gain it can get. If you keep your swifts fit and strong it can only be a good thing, and until better research comes along it makes sense to follow that guidance if you can. I'll reiterate the importance of this; Just two swifts gained from any cause related to this parasite, could, in theory, create over 500 additional swifts in two decades. There will be other losses in these totals of course, but it shows what the long term impact could be. Every little helps, as Tony said earlier.
 
If anyone in this group has a faithful, regular pair under a camera, where the flies can be clearly seen at the moment, and/or where the swifts show irritation - would they please disinfect the nest this winter and check what happens next year and consequently? This citizen science is the way we can do some of our own research.
 

 
Thanks
 
Ron
 
On Sunday, June 7, 2026 at 1:45:09 PM UTC+1 audrey...@gmail.com <mailto:audrey...@gmail.com> wrote:
 
In case you haven't seen this and it is of any interest.
 
From Edward Mayer a while ago.
 

 
https://pmc.ncbi.nlm.nih.gov/articles/PMC3029137/
 

 
On Sun, 7 Jun 2026, 11:03 Carol Collins, <carolwc...@gmail.com <mailto:carolwc...@gmail.com> > wrote:
 
Hi Tony,
 
Yes, it would be good to think you might be but I have no idea how long the pupae can survive - obviously over one winter but perhaps longer? My experience of watching them does make me wonder whether a build up of Crataerina numbers might cause a colony to move? There are dozens of old nests under my eaves (apprarently a mixture
Dick Newell <dick....@gmail.com>: Jun 09 08:59AM +0100

I must say Ron, after many years of watching swift webcams, I have never
witnessed the kind of distress that you describe. I see Swifts fidgeting
all night when there are no flat flies, and I have seen swifts with a lot
of flat flies which they seem to ignore. They also fidget.
 
Do you not think that the immense fear that some people have of spider-like
things is colouring their thinking?
Personally, I like spiders.
 
This year, so far, I have seen very few flat flies. This surprises me when
we have had quite a few warm days this spring, which is supposed to be
favourable for them. I spent some time scrolling through Jaap's webcams and
didn't find any.
 
Good luck with your research.
Dick
 
Hythe Scream <hythe...@gmail.com>: Jun 09 05:47PM -0700

Some people don't like spiders, but I don't think this has got anything to
do with that really because we don't usually handle them. Ive seen one run
up a re-habber's arm very quickly though 😀
If it's a bad year for the Crats, then that's a bonus.
I'm only responding to the initial OP's comments really. It made sense on
reading the info, watching youtube, and listening to responses that I've
since had and read about from various other sources, that it's time to see
what can be done, if we are able to. It's not about wiping out a parasite,
which can't be done. It's about maximising your output to this worthwhile
cause, and knowing that you are helping a sentient creature to live a
comfortable life and maximise their chances of a long and productive life
which goes towards the aim of saving the swift from further demise.
 
I've offered to take this research on board, and will ask formally for
volunteers in a seperate post. If anyone comes forward to take part, then
I'll do the paperwork. If they don't then I'll leave a summary of advice
that I've collected so people can do what they wish going forward.
 
Thank you to all those who have contributed to this conversation. I've read
them all.
 
Cheers
Ron
 
On Tuesday, 9 June 2026 at 08:59:45 UTC+1 Dick Newell wrote:
 
Edward Mayer <edward...@zen.co.uk>: Jun 09 10:13AM +0100

Erich Kaiser who had  a colony of about 90 Swifts used a cage-bird
insecticide sold by the pet trade to eliminate Craeterina. He also
collected the black pupae if ever he found them in his accessible nest
boxes. His colony was extremely successful. A simple disinfectant will
not kill Craeterina, unless used in massive quantities when it will harm
everything else too. But something like this could do the job, maybe?
 
www.fabfinches.co.uk
 
Vetafarm Avian Insect Liquidator (AIL) Bird Mite Spray - Safe directly
on birds, newly hatched chicks & in nest boxes - Fab Finches UK <#>
 
Vetafarm Insect Spray eliminates and controls mites and lice on all
birds and their housing. Protects for up to 6 weeks. It is safe enough
to spray on newly hatched chicks but deadly to insects including mites,
lice and ants! Recommended for: Use on bird mites, lice, flies, spiders,
ants or any situation where external parasites are a problem, including
nest boxes, flights, perches, aviary floors, indoor cages and for direct
application to the bird. Ensure your birds housing is Mite free
 
🔗
https://www.fabfinches.co.uk/product/vetafarm-insect-liquidator-for-mites-lice-cage-bird-disinfectant-cleaner/
<https://www.fabfinches.co.uk/product/vetafarm-insect-liquidator-for-mites-lice-cage-bird-disinfectant-cleaner/>
 
 
 
Tony Croft <the.cro...@gmail.com>: Jun 09 10:58AM +0100

That looks interesting. Thanks for posting Edward.
 
 
Best Regards
Tony
 
On Tue, 9 Jun 2026, 10:13 'Edward Mayer' via swiftslocalnetwork, <
Hythe Scream <hythe...@gmail.com>: Jun 09 05:21PM -0700

Thanks for that Edward, I'll add that to the research plan.
 
On Tuesday, 9 June 2026 at 10:59:10 UTC+1 the.crofties~Hathern wrote:
 
Nick Brown <brown...@gmail.com>: Jun 09 07:49PM +0100

Hi again
 
Many thanks to everyone who has now registered one or more events for *UK
SAW2026.*
With just under two and a half weeks to go, the national list now has* 80
events* taking place within the nine days of SAW with several more either
side as well so that's all helping to build SAW into something big across
the country.
 
Please do keep them coming so we can reach the same number as last year!
The umbrella of SAW provides the very best opportunity to promote what you
are doing locally.
 
*Here are the links to:*
The essential SAW registration event form: *https://tinyurl.com/SAW 2026
event registration <https://tinyurl.com/SAW2026eventregistration>*
The national AfS list and map so far: Action for Swifts: SAW events 2026
<https://actionforswifts.blogspot.com/p/saw-events.html>
The RSPB's list of SAW events so far: Swift Awareness Week
<https://www.rspb.org.uk/whats-happening/swift-awareness-week> (This will
be updated before the week starts).
 
And just a reminder to get your *publicity *organised early and also to
include the *SAW logo *to show your event is part of a big national one.
 
Best wishes and let's hope the weather picks up by the 27th!
 
Thanks,
 
Nick and Peta
[image: SAW logo 2026 final at 23rd March ssLL.jpg]
Ros Taylor - Kendal Swifts <rosalin...@gmail.com>: Jun 09 02:21AM -0700

We have a bit of a mystery from our swift watching last night (Monday
8th).
We watched a swift circling around the side of a building where we have
seen swifts and house martins nesting in natural sites for some years.
Finally the swift tried hard to enter a site which we have only ever seen
occupied in 2018. However, the swift did not get in (acting much like a
banger), and eventually, I am sure that a House Martin went in to that
spot. No sign of usual mud nest cup.
Has anyone seen this happening? Is it likely to be a banger, or an adult
which has occupied the nest site before.
Many thanks
Ros Taylor
Kendal Swifts
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Heidi Collishaw

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Jun 10, 2026, 8:45:28 AM (3 days ago) Jun 10
to swiftsloc...@googlegroups.com
That's great news John. Well done for securing this outcome, and do please pass on my/our thanks to their team, for making a good decision 😉.
Regards
Heidi
Westow swifts. North Yorks.

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