top of page

Dear BTO - part 2

Following our earlier blog about the BTO website which you can read here - and the earlier pdf which is linked on that blog - I have written directly to the BTO (see emails below) and asked them to change what I believe is a misleading statement on their website about the reasons for the decline of Swifts. I’m told that there may soon be a change to that wording which is good news, though whether it will go far enough remains to be seen, so we’ll wait and see.

I understand scientists’ caution in this regard but I have quoted several examples from here in Hampshire where providing Swift boxes/Swift bricks can, in time, greatly enhance a population which would have either gone extinct or simply not have existed at all. And I could quote many others like the Hospital of St Cross in Winchester which has gone from two pairs with young last year to nine pairs rearing young this year all in internal boxes installed just three years ago. A blog about that exciting development will follow soon. More importantly I know of no sites where we have installed Swift boxes where the number of Swifts is declining rather than increasing. And Dick Newell in Cambridgeshire (not far from the BTO Thetford HQ) has quoted similar examples on churches below, and could no doubt quote many others. How can that possibly square with “the loss of insects is the reason for the decline”? We know that Swifts can take some time to adjust to using boxes or Swift bricks but once they do the increase in population size can be dramatic.

What research has the BTO done to show that that is the case? What effect does the BTO believe the loss of nesting sites due to installation of plastic fascias and soffits on existing houses in the last 25 years has had on our urban bird species? Do they think it is none? What effect does the BTO believe that changes in building practices on the construction of new homes in that time has had on our urban bird species? Do they think it is none?

The reason this is important is that during the last 25 years we have lost ~65% of our swifts, that’s approximately 100,000 pairs and they are still continuing to decline at ~5% per annum. Putting up Swift boxes, however much fun it is to save our local colonies, is not the solution on its own. We have to be installing huge numbers of Swift bricks at an average rate of one per dwelling in all new homes as well, and to do that we need to put pressure on Government. We can’t put pressure on Government if the BTO's website says that the reasons for the decline aren’t clear. Even then it will be years before we can stop the decline nationally. This is on your watch BTO. And it has been since the 11,269 survey forms were returned to you in 2004 showing that 7% of those people had had gaps in their roof blocked in the previous year alone. Please correct your website.

Sometimes scientists do excellent, valuable science but sometimes they get things wrong and sometimes they don’t do the right science. That’s the nature of science and peer review. And often science can be slow. Far too slow sometimes.

Time is not on our side. With COP26 rapidly approaching and a new Minister for Housing in place we do have a slim chance of getting the Government to listen and do something positive to help our urban birds.

Tim Norriss

BTO member

See below full emails to the BTO and information from Dick Newell on Swifts nesting Swift boxes on churches

Swift emerging from a Swift brick. Photo: Simon Stirrup

From: Tim Norriss Sent: 31 July 2021 15:01

To: BTO Subject: FW: [SLN] Church swift project occupancy

I thought you might be interested in the email below from Dick Newell showing increases in Swifts in all but one of his churches with swift boxes this year. It doesn’t seem like a loss of insects is a problem here!

The problem I have with the BTO not stating very clearly that the problem is a loss of nesting sites is that it gives a mixed message to Government, Councils, ecologists and everyone else that as we don’t know what the reason for the decline is there’s no point in putting a ‘swift brick’ into all new properties as requested by the RIBA, RSPB, NHBC and many other conservation orgs as it might just be a waste of time and money.

These are the reasons given for decline of Swifts on the BTO website:

“The causes of the decline are unclear. Modern building design and refurbishment of old buildings may have contributed to the decline by depriving Swifts of nest sites, but the complications in monitoring trends and nests (as described in the Status Summary) make it is difficult to confirm and identify the likely main drivers of change.”

Putting it bluntly, that is not true. ‘…may have contributed to the decline’?? It is blindingly obvious to everyone working in Swift Conservation that the two reasons given are the two main factors in the decline. Since the BTO website is the go-to point for information on this subject it is extremely unhelpful for misinformation like this to be put there as it just lets the Government and Councils off the hook and allows them to carry on doing nothing to help our crevice-nesting birds. I would ask the BTO to correct this highly erroneous statement.

Is this the reason why the housing minister declined a request for Swift bricks in new housing to be made mandatory? - quite probably. Is it the reason why Winchester City Council haven’t agreed to make Swift bricks mandatory in their Local Plan that is currently being finalised? – quite probably.

And for Starling the BTO give the reasons for decline as:

‘There is good evidence that changes in first-year overwinter survival rates best account for observed population change. Although the ecological drivers of Starling decline are poorly understood, changes in the management of pastoral farmland are thought to be largely responsible.’

There is not a mention of loss of nesting sites as being even a potential cause of the decline. My own view is that the BTO is doing our crevice-nesting birds a great disservice. Is it not quite possible, or even likely, that the cause of the decline might be in part the same as that of Swifts?

Whilst I suspect that you would say that there isn’t the science to prove it, I would just say that’s because the BTO haven’t done the right science. What does your data on Swift fledging success show? Surely modelling on effects on nesting birds in houses could be done by analysis of roof repairs done, soffit replacement with plastic and modern house-building methods?

We have lost 2/3rds of our Swifts in the last 25 years and they are continuing to decline at 4-5% per annum. When will the BTO do the right science?

I’d be grateful if you could pass this email on to Prof. Juliet Vickery.

Many thanks


From: On Behalf Of Dick Newell Sent: 27 July 2021 08:13 To: Swifts Local Network Subject: [SLN] Church swift project occupancy

We (Simon Evans, Bill Murrells, Matt Dijkstra and I) have recently inspected a number of our belfry nest boxing projects, finding a total of 187 boxes out of 345 occupied by Swifts. The summary breakdown is below.

All churches increased this year except Worlington, where we suspect a predator problem. We don't know of any other single building colonies larger than St Mary's Ely with 58.

St Neots 47/60: 78% Worlington 20/43: 47% Ely 58/96: 60% St John’s, BSE 42/60: 70% Landbeach 16/68: 24% Santon Downham 4/18: 22%

Totals 187/345: 54%

450 views0 comments

Recent Posts

See All


bottom of page