The BBS report covering 2012 is out – here is the link.

The results: the results are the most important part of the report.  You should look at them, but here are some of the things that struck me, mostly concerning the long-term trends rather than the 2011-12 changes:

  • there are a lot more greylag geese, ring-necked parakeets and red kites in our little UK world than there used to be – only one of these is a thoroughly good thing, in my opinion.
  • great-spotted woodpeckers continue to increase in numbers
  • blackcaps and chiffchaffs are commoner, most warblers (of those covered by BBS) are much the same but the wood warbler continues to dive in numbers.
  • the Game and Wildlife Conservation Trust have failed to conserve the grey partridge despite their best efforts and it being one of the best-researched bird species in the world.
  • if you have never seen a turtle dove in the UK then you’d better get to SE England next year as you don’t have that many years to go at this rate.
  • the UK sparrowhawk population is about the same as it was when the BBS started – don’t worry about being overrun by them!
  • the UK magpie population is about the same as it was when the BBS started – don’t worry about being overrun by them either!


The report: the report is very well designed.  Considering it has lots of number-heavy tables (which I love! I’m not complaining) it looks very attractive and is readable.  This takes quite some thought to achieve and it is, again, well-achieved here.

I have two more detailed comments to make on the presentation of the report.  One is a niggle, but not a criticism as I think I understand the reason behind it, and the other is somewhat pedagogical in nature.

In the tables (eg Table 2) we are given the 1995-2011 trend and the single year, 2011-2012 change.  This makes it quite difficult to work out how much the overall change is from 1995-2012. Well, when I say ‘difficult’ it’s not beyond me but it isn’t completely straightforward (unless I have misunderstood (which is always possible)).  Here’s an example; the turtle dove trend was -85% between 1995 and 2011 and -14% between 2011 and 2012.  How much did it decline between 1995 and 2012?  Come on – quick! – how much?  I think its index in 2011 was 15 and that declined by 14% (a seventh) and so the index in 2012 was 13 and so it had declined by 87%.  Is that right? And, if it is, did we all get that answer – be honest now?

Might it not be easier to have the 1995-2012 trend and the 2011-2012 trends instead of what we are given? I doubt, but I may be wrong (or missing something), that many people want to know the 1995-2011 trend.  It’s a small niggle but it niggles me every year so I have unburdened myself of it  (and feel much better for it).

And now let me get this next point off my chest too – it’s not a complaint.  If you look at the graphs in the report (of population index against year over the period 1995-2012) they are very interesting.  Have a look at the greenfinch graph on p12 for example.   I love graphs!

By Milton H. Greene [Public domain], via Wikimedia Commons
By Milton H. Greene [Public domain], via Wikimedia Commons
Going back quite a while, the BTO used to get graphs ‘wrong’ in this and other publications.  They went through a phase of just giving us a line of best fit but not showing us the data to which the line had been fitted.  This is shocking behaviour and I am glad that it has ceased.  Just because one has a programme (or program) that will fit a line to any data doesn’t mean that you should, and even if you do, you certainly shouldn’t leave out the data so that the human brain can’t examine them too.  The variation from year to year is what is interesting – it shouldn’t be hidden.

You can maybe see what I mean if you do look at the greenfinch graph.  There are lots of nice black dots which represent the hard work of a few thousand people like me (and you?) and then there is a trend line fitted in the twinkling of an eye by some computer programme.  The graph is an interesting one, and I’m very glad to see it, and the line of ‘best’ fit isn’t a bad one – it curves beautifully likes Marilyn Monroe’s hips – but I would question whether it is the best line for those data.  And like Marilyn’s Monroe’s hips, it is a bit distracting – but I am made of stern stuff and am not easily distracted.

The line of ‘best fit’ portrays the highpoint of the greenfinch trend (2006) as a bit of an outlier whereas, in my opinion, there is a ‘better fit’ line that follows the trajectory of the 1995-2005 increase and then plunges more sharply down after 2006.  The actual points on the graph, the real data, suggest that greenfinches were increasing, gradually, year-on-year, right up to and including 2006 and then something happened – and the population started to decline sharply before the 2007 counting season.  But the line of ‘best’ fit would tell you that greenfinches started to decline in 2006, in fact they may well have been thinking of declining and trying to decline in 2005 – it moves the decline point by two years.  The dots are ‘real’, the line is a computer programme attempt to describe the data.

I feel better for that too – and part of the reason for making this overly long point is that it’s really good that the graphs are very clear so that we can see what actually happened. There is a place for fine curves – Marilyn Monroe was a very fine place for quite a few – but I’m glad we can see our scruffy data too.


The logos: just have a look at the logos of the three organisations supporting the BBS.

The BTO logo (hardly ‘new’ any more) looks good.  It’s friendly and birdy, and has, in some strange indefinable way, a touch of humour to it.

The RSPB logo is new, but since it has hardly changed it seems hardly new!  However, it struck me that the new strapline ‘giving nature a home’ looks at its most twee (tweeest? twee-est?) on the cover of a report such as this.  But that means that it will look right in lots of other circumstances, I guess.  But maybe they are circumstances where I won’t see it much.

JNCCLogoAnd then there is the JNCC logo.  I bet hardly any reader of this blog really knows what the JNCC is, what it does or why it needs a logo.  I, myself, wonder sometimes.  And I’d be surprised if, at this size, on this post, you can tell what the logo is trying to do. I’ve got it now but I did spend some time trying to work out what that white (sometimes dark) shape was – until I realised I should be working out what those three black (sometimes light) shapes are.  It’s probably just me, but I dislike generalised birdy shapes (particularly dove-like generalised birdy shapes for some strange reason!). And is that a leaf – I’m not sure (it might be a plaice!)?


The changes for next year: how exciting! I’ll have to do something a bit extra and a bit different next year (well it’s voluntary but I am a participant in life so I’ll probably give it a go).  The BTO (and new-logoed partners) are asking us to record whether we first record birds by sight, call or song in order to calculate bird densities more accurately.  This will mean a bit more data entry for me (and you if you survey a square) which might make people moan a bit but it goes with the territory (as it were).

The more data entry is done by the observers, as volunteers, the better.  The better because we are the people most likely to spot any typing errors (my data entry errors on BBS usually come from not remembering the species codes and ending up entering a gannet instead of a greenfinch – don’t worry these are always (?) corrected.  But also the better because data entry costs money. And just as I am paying for the fuel that gets me to my BBS squares I am contributing my time freely to the data entry – this generates a huge saving for the organisations involved and should speed up everything a lot.  If you are still wedded to paper, please get divorced and choose to enter your data over the web.


A few thank yous: the BBS is a great monitoring scheme and I’m pleased with the part I played in helping to set it up (see Fighting for Birds Chapter 4).  It’s traditional to recognise the contributions of the volunteers at this point, often in a rather cringe-making way, but we just love getting up early, spending our time and money and seeing birds, so no thanks are needed.  Instead I’d like to thank the BTO for their work, especially, I guess, Kate Risely who is the current BBS National Organsier (but also all others involved).  And let’s remember the funders too.  Some of our taxes are well-spent through the contribution of the JNCC to this work and I’m glad that that happens.  Also, the RSPB is a major funder of this work and has been since the start of the BBS (in fact, before the actual start) – I know this because I had to find the money out of ‘my’ budget and it wasn’t always easy.

I’d also like to thank my regional BTO organsier, Barrie Galpin – Barrie is great!  I only met Barrie for the first time at the BTO Conference at Swanwick last year but he has been telling me what to do for years.  He is very good at sending around emails,  personal emails and general reminders, to us all that we ought to be getting ready for the next census challenge.  And he’s great at feedback too.  After I enter the data online I always get a message from Barrie which shows that he has noticed that I have done my bit and always demonstrates that he has had at least a quick look at the records too because he comments on interesting sightings. So thank you Barrie, and all the other regional reps (even if they aren’t all as brilliant as our Barrie).  There’s a list of Regional Reps at the back of the report and I recognise quite a few names.  There are not enough women’s names, although a slightly higher proportion than I expected, so maybe that is an area which is improving.

If I write much more it’ll be time for next year’s survey! The most important thing is that we are privileged to have such a wonderful, reliable, annual snapshot of the state of the populations of commoner bird species.  It’s fantastic!  The BTO is fantastic!  We birders are fantastic!

I, Daniel Schwen [GFDL (, CC-BY-SA-3.0 ( or CC-BY-SA-2.5 (], via Wikimedia Commons
I, Daniel Schwen [GFDL (, CC-BY-SA-3.0 ( or CC-BY-SA-2.5 (], via Wikimedia Commons

23 Replies to “BBS”

  1. Birders are fantastic? Can’t argue with that! I’m sure the BTO will note a massive increase in data submission this morning. I’m finally getting round to entering mine right now!

    Definitely much better that we all do it than one or two poor souls in an office spend half their lives tapping in data. I’m sure they would spot your gannets though, or the two dunlins which were almost just recorded as residing with yellowhammers in a Hampshire hedgerow 😉

  2. Hi Mark – Kate Risely wanted to reply but she’s out at a meeting today, so just a few words from me.

    Firstly, thanks very much for your supportive words (and for your counts of course!) Yes, it’s not easy to make a report on annual trends exciting and colourful but I think Kate’s done a great job again here.

    Secondly, you raise a good point re the trends. Actually, you kind of answer it yourself, when you go on to talk about smoothing vs actual index points. The point is that the long-term trend is based on the smoothed line, i.e. comparing the smoothed value in 2011 to that in 1995. This is felt more appropriate that comparing the actual index values because to do the latter, you’d be very prone to the vagaries of one-off peaks and troughs in both the start and end years. Your long-term trend would jump up and down a lot between years, which we’ve always felt is potentially more confusing than using the change in the smoothed values.

    So why, I hear you ask, don’t we compare 1994-2012 smoothed values then? Well, it’s because the statisticians tell us that when we’re adding a smoothed line through a series of points, we should be very wary of the end points, and should remove them. This makes sense – clearly, a smoothed value for 2012 is (in due course) going to depend strongly on the 2013 value, which we don’t yet have. Hence, we’ve always been advised it is safest to chop off the start (1994) and end (latest, here 2012) smoothed values and describe the difference between the second and penultimate years instead.

    Of course, this is the 2012 report though, so there’s lots of interest in what happened in 2012. So, we try to balance the desire for the most up-to-date picture vs the statistically recommended long-term approach by also giving the % change between 2011 and 2012 actual index values (not smoothed values).

    So, your quick calculation of overall 1995-2012 change is ROUGHLY right, but not quite, because it’s combining the smoothed 95-11 with the unsmoothed 11-12.

    Anyone still following?! In short, it’s difficult to come up with the ideal solution for summarising the results, but this is what we’ve got. Indeed, the best approach if you’re interested in a given species is to look at the individual graphs – these are all online at (and you can get graphs for individual countries and English regions here also).

    Finally, good points on the graphs and I agree it’s best we show both the “real” index points and the smoothed line. The other presentational point that I remain undecided on though is whether the y-axis should always go down to zero, or not (the latter is the current approach, e.g. the Greenfinch graph on p12 has a y-axis between 50 and 150). I personally have a feeling that there may be an argument for the former? There are pros and cons both ways – would be interested in opinions?

    Thanks again for your support anyway. Hopefully see you (and other readers) at Rutland this coming weekend at the BTO stand (or wandering around as usual, trying not to buy too many books on obscure insect groups!)

    Andy Musgrove

    1. Andy – many thanks, indeed, for that. What a very full answer. If I’d really thought about it enough I could have got there myself I guess.

      The fact that the long-term trends are based on the smoothed trends and the year-on-year changes aren’t, explains, of course now I think about it, why the year-on-year changes sometimes seem quite big – it’s because they are but they won’t seem so big when they are smoothed out (next year)! I would hazard a guess that there aren’t many people who look at the tables and realise all that. And there may be very few who care, but I care, and now I feel I understand them even better – thank you!

      It can’t make much sense to chop off the first year – ‘cos you can’t go back in time, ever, to do the year before. Why not chop off the first two years? or the first three?

      And I would, partly because no one should have their life run by statisticians, be inclined to use the last year (the year of the report!) in the long-term trend tables. And for two reasons: first, that is what we are all interested in and second, because you use them in the graphs (as you point out) so it is inconsistent not to use them in the tables (and how did you then persuade the statisticians that you could use the Scottish linnet graph – which appears to be based solely on one year (cakes – having and eating them?)?). The trends jig about a bit from one year to the next anyway so you aren’t really protecting the reader from having to change their mind a little about what is going on through this device. You must not pander to the insecurity of statisticians too much. But, I’m so thrilled with the report, and my thrill-quotient has been topped up by your reply that teaches me some more stuff, that I really don’t mind what you do.

      Your point on the Y-axis – I wonder what others think. I see your point. For presentation sake if you made the ‘100’ very obvious in each graph and also broke the axis if it didn’t go to ‘0’ that might get the message across.

      Thank you for your comment. And thank you all for a fantastic report. See you at the Bird Fair!

      1. With regards to the y axis and whether it should go all the way down to zero I guess it depends on how carefully you expect people to read the graphs. For someone who is going to scrutinise them thoroughly and think hard about what they show it probably does not make too much difference but for someone (such as a politician) with a more superficial approach it can be important. When presenting something like the unemployment figures the presentation people can make a small improvement seem much more significant if the y axis is truncated (although of course only a cynic would imagine that politicians would stoop to such a cheap trick!). The flip-side, of course, is that it can become too difficult to see small changes from year to year if the y axis goes all the way to zero on a long scale.

      2. Good answer Andy, it took me awhile figure it out too.
        One more point for consistency: As you have decided to always ignore 1994, except for calculating the trend line, should not the graphs be normalised to 1995 at 100. Right now, as, I think you have set 1994 to 100, then the decline you give is not 100 minus the y value on the graph – which it logically should be, because the y value is based on 1994 and the decline is based on 1995 – kind of inconsistent.
        Also i assume that when you have the 2013 report, the index value for 2011 might change a tad? Which is OK by me.
        Now a dig – when are you going to replace the silly numbers on the y-axis pf the graphs by sensible ones, so one has a chance of reading some values.
        These reports make fascinating reading every year – well done BTO/JNCC/RSPB

        1. Dick – there really isn’t any justification for dropping 1994 unless it is thought to be an odd year. I can see dropping the most recent year (just about) because things might change.

          1. Hi Mark,
            I think that either:
            Keep 1994, normalise the graphs to 1994 and quote the change each year relative to 1994
            Drop 1994, only using it as an input to the trend calculation for 1995, normalise the graphs relative to 1995 and quote changes relative to 1995. I don’t mind which, it is the inconsistency I don’t like.

    1. Douglas – thanks! I’m just not quite sure what the JNCC logo has on it – I’m such a poor naturalist.

      1. I had never looked closely at the JNCC logo, which, if that is true of most people, is perhaps something that should worry the JNCC. Initially I thought it was an image of the Earth, which didn’t make sense. Then I mystified as to why the JNCC would think anyone would notice there is a dolphin, bird, and, oh yes that does look like a leaf…

        There are some logos that make sense, and some that make you marvel at that someone got paid lots to create that!

  3. The designer of the JNCC logo states:
    “It is a leaf from recollection” (quote).
    There you go Mr.Avery…. you were quite correct with your first assumption.

  4. JNNC try and do a useful job…they have just published a red data list for bolete fungi….a very significant step towards the conservation of the missing third of our biodiversity!

  5. Hi Mark,

    Thanks very much for your kind words about the BBS report – I’m really pleased that you think it’s attractive and readable!

    Thanks also for your comments about the smoothed/unsmoothed trends, and the graphs. I think Andy has covered everything I would have said about these, but you have made me think about how these figures aren’t necessarily as clear as they could be, and I’ve got a few ideas about how to improve the interpretation for the next report.

    Just to clarify a small point in your discussion with Andy above – when we smooth the trend, and present the trend between the second and penultimate years of the series, this doesn’t mean we discard the data from the first and last years. These are still used, thus ensuring that the years we use for the trend (the second and penultimate) have data ‘on either side’ to help with the smoothing.

    You say in your blog that ‘The variation from year to year is what is interesting’ – but I’d make the point that this depends on what question you are asking! I tend to think of the smoothed and unsmoothed trends as very different tools to be used for answering different questions, depending on whether you were interested in the ‘real’ annual population fluctuations or the (also real!) long-term population changes. I definitely agree that both should be presented on the graphs.

    Great to hear that you’re up for trying the new survey methods next year – I look forward to a blog about it! And finally, what nice words about Barrie Galpin, who is just one of our very many invaluable, hard-working Regional Organisers.

    Sorry for leaving Andy to respond; I was at Stamford helping to plan this year’s New Networks conference. Hope you are planning to come again this year?

    Thanks, Kate

    1. Kate – thanks. You’ve had a long day then. Great survey and great report. Thank you.

      See you at the Bird Fair and yes, I’ll be in Stamford (I think I may be chairing the last session).

    2. I will definitely be using the new recording techniques next year. Anything that reminds me of the detail of Common Bird Census recording gets me excited (how sad…). I enjoyed using the Short Field Recording sheet this year, and I think this extra data can still be accomodated on that sheet, but not a problem if it can’t. I am also a great fan of entering data online for the reasons stated elsewhere. And I enjoyed the report very much this year. Following Mark’s lead, thanks to Kate and her colleagues at the Nunnery, and also Tom and Muriel Cadwallender, the Northumberland reps who are currently holidaying in Australia.

  6. Gannet and Dunlin might be readily picked up but I have one salutary tale about mis-recorded species codes. During our local (tetrad) atlas project for Cheshire and Wirral 2004-06 we were fortunate to have, as well as the usual BBS transects, data from some extra squares that were visited on behalf of DEFRA by professional (paid) surveyors, using BBS methodology to monitor the effectiveness of ELS (Entry Level Stewardship) in helping to conserve farmland bird populations.

    I was surprised to see that Marsh Tit appeared to be relatively common on Cheshire farmland – noticeable because we are one of the counties where Marsh Tit is scarce, scarcer indeed than Willow Tit ( – and eventually I realised that one of the surveyors had used MT as code for Mistle Thrush (which should be M.). His records had been entered by someone else, without local knowledge, and the error not spotted until I noticed it, a year or two later!

    1. David – I always find mistle thrush (M.) difficult to remember, but I find marsh tit (MT) difficult to see. Thank you.

  7. The BTO surveys are excellent and always produce interesting data for discussion. In the end, of course, it is how this data is used for bird conservation. The data highlights many species that appear to have serious problems eg turtle dove. Who is going to work to reverse these trends? Now that the focus of the rspb is “Wildlife” not birds, the rspb will have to balance its reserves portfolio eg by buying and managing flower and invertebrate rich chalk grassland sites and by funding non avian taxa projects eg saving hedgehogs. To compensate for this will the BTO now seek funding not only to identify the problems facing some bird species, but also solutions to the problems? Does the BTO have plans to seek funding to buy and manage important sites for breeding nightingales?

  8. Clearly the JNCC is all about fish. The one on the right is clearly a typical fusiform fish, the bottom-left is a plaice or similar and the top-left one is a slightly wonky mobula seen from the side.

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