Sparrowhawks responsible for House Sparrow decline says scientist (1 Viewer)

[citrinella]

Mike – I don’t think I’m in competition with agri-environment researchers, since I work on whatever grabs my curiosity rather than following where the money leads, which is probably why I haven’t had a farthing to do research from any source these fifteen years.

I'll let you off on that then Sounds like me - I do the conservation and worry after if I can get any money (not often).

My problem is not with agri-environment management per se, but with the underlying philosophy that all ills can be blamed on ‘agricultural intensification’, and that we need to create a simulacrum of the arcadia that existed immediately after WWII. This idea is so entrenched that the outcome of virtually every study is parlayed into evidence ‘in favour of’ or ‘consistent with’ the initial premise. The Hole study mentioned earlier is an example of this, as is the Peach study in the context of changes in the urban landscape.

I have this problem with "blame agriculture" too. However (see below) I do think there is a problem, and I want to help fix it. My problem with "blame agriculture", several actually are :
other problem areas are being neglected, in particular the behaviour of the general population*;
land managers, key to solutions, are being alienated, rather than encouraged to help. That is one of my biggest issues with the current subsidy system. Too much money for doing too little (usually nothing), too little money for doing a better job with, worse, incredible bureaucracy. Lastly, the reservoir of knowledge within land owners is being ignored and in the current climate, dissipated - ivory tower research means office based bureaucrats know best with their checklists and menu options, too simplistic.

*No, I don't want to turn a torrent of criticism at the populace. I want to spread information and encouragement as widely as possible. A little happens, but far more could be done. When I suggested public education on the benefits of native broad leaved species in people's gardens, the then Scottish Environment Secretary said "I am a gardener and there is no way I would tolerate weeds in my garden." OKAY, he wouldn't, but that is no reason why every gardener in the country should not be fed the information and given the choice.

I also find the Skylark study carried out under SAFFIE to be fishy to say the least. The premise is that Skylarks have declined because of a switch to autumn sowing, which means that the crop is too high for them to nest in by spring. We will therefore create 4x4m unsown patches for them to nest in and do an experiment on 15 sites with control plots and plots with unsown patches. Lo and behold, Skylarks density is higher and nesting success greater in plots with unsown patches. Except they aren’t nesting in the patches. Never mind, it must be because of improved food availability. Except the patches are so small they can’t possibly make a difference, and anyway, how could the Skylarks have known the patch plots were going to have more food? Is it possible the higher density merely shows that the patch plots happened to be on better habitat? I ask myself how much randomisation was done, or can be done when 5 hectare plots are being used.

Hah, so science has turned up an awkward answer that you don't understand. That is what is good about science. Doctors (mind, I work in a medical research department) learnt physiology, anatomy, biochemistry, basic science and traditionally worked out wehat to do themselves. Once it appeared to work for a patient or two, they went on and proapgated it as marvellous for everybody. That was how medicine developed until quite recently when Archie Cochrane stodd up and said RUBBISH. Fortunately he has been listened too. Better science has been applied and a lot of the mechanistic ideas have been shown not to work, even to do harm. Quite often we don't understand why. Robust, large scale, randomized trials rubbish approaches which appear based on sound principles. Things are sometimes shown to work long before we can work out why.

The SAFFIE randomisation on my farm seemed pretty good to me. Historic skylark densities were taken into account along with loads of other factors to try to minimize underlying differences between plots. For instance, one of my large fields was known to have lower densities at one end so was divided across so both plots had equal areas of high and low densities. Other fields had similar avearage densities to those plots. I was told that my farm had a bit more variation than desirable. However plot randomization was used, and across the whole UK (40 odd farms, not 15), that should have balanced out pretty well.

When funding is based on the premise that agricultural change destroys biodiversity, it’s essential to avoid drawing inferences that call this into question. It’s much better to do half-baked studies that produce equivocal results, which can then be spun into a favourable story. However, this is unlikely to provide a sound basis for effective management. Such equivocal outcomes also have the merit of requiring yet further research, so ensuring that the funds keep flowing, and that’s why they are so terrified of our paper. It provides a clear cut, unequivocal answer to a problem, and every time a problem is solved, a research career dies.

Sorry we have been drawn so far from the original topic. Yes, science needs to be challenged - Archie Cochrane initiated a complete (ongoing) revolution in medicine. I am quite happy with your paper (but no amount of research let alone one piece ever produces a clear cut, unequivocal answer, in science that is impossible). I am glad you are standing up to the criticism as it is important to accept that your research shows what it does. I just hope that is accepted, but it is built into a management program that accepts the influence of sparrowhawk within the wider food web, and does not attempt to destroy sparrowhawk in an attempt to distort the web.

If science does have a part to play in conservation on agricultural land, and I think it does, it needs to be hard-nosed science that isn’t afraid of challenging shibboleths like agricultural intensification, or indeed predation as we have done in our study. Unfortunately, the answers that such science can provide may be rather limited, so it holds no attraction for empire builders. The rest, as I suggested in the earlier post, should be down to judgment calls from the likes of yourself, suitably incentivised by results-based subsidy.

OK. You seem to be challenging the role of agricultural intensification in degradation of biodiversity, that the move from spring cropping to winter cropping is not harmful. I have lived on East Lothian mixed/arable farms all my life, (except two years on a farm near Dumfries), have looked at farms up and down the UK and abroad, and am astounded. The changes in agriculture have brought enormous simplification to ecosystems :
far fewer habitat types;
far fewer species;
far fewer food sources;
far less unimproved ground;
vast reduction in wet/water features;
far higher inputs of chemicals which may or may not have good sides as well as bad (I practice conventional agriculture).
These have been deliberate policies of intensification. It is not good enough to say that these effects are not linked to agri-intensification, they are how agriculture has been intensified.

Now, I see myself in the position of many doctors, astounded that the mechanistic principles they had used for so long could be proved wrong, but they were. I see cause and effect before my very eyes. Your role would be to get on and prove me wrong - please be my guest, world agribusiness surely would be delighted to make you very rich indeed, if you succeed

I am not saying that other things - urbanization including infrastructure across our rural areas being a prime example - are not important impacts on biodiversity. The challenge is to show that agri-intensification on its own is not an important impact.

Or is that not what you were suggesting ?

Mike.

 

[CPBell]

land managers, key to solutions, are being alienated, rather than encouraged to help. That is one of my biggest issues with the current subsidy system. Too much money for doing too little (usually nothing), too little money for doing a better job with, worse, incredible bureaucracy. Lastly, the reservoir of knowledge within land owners is being ignored and in the current climate, dissipated - ivory tower research means office based bureaucrats know best with their checklists and menu options, too simplistic.

Yep – we agree on that, and no mistake. However, I think the issues that particularly exercise me feed into this problem (see below).

Hah, so science has turned up an awkward answer that you don't understand. That is what is good about science. Doctors (mind, I work in a medical research department) learnt physiology, anatomy, biochemistry, basic science and traditionally worked out wehat to do themselves. Once it appeared to work for a patient or two, they went on and proapgated it as marvellous for everybody. That was how medicine developed until quite recently when Archie Cochrane stodd up and said RUBBISH. Fortunately he has been listened too. Better science has been applied and a lot of the mechanistic ideas have been shown not to work, even to do harm. Quite often we don't understand why. Robust, large scale, randomized trials rubbish approaches which appear based on sound principles. Things are sometimes shown to work long before we can work out why.

This is the kind of science I’m arguing for, but which I don’t think is being carried out. So much of the stuff that I read in this area talks the talk, but doesn’t walk the walk, and ends up being used to give an undeserved scientific imprimatur to ideas that are really no more than the kind of folk wisdom that you’re referring to. Writ large and implemented via a bureaucracy, it doesn’t work, though as you say, it might do in prescribed circumstances on the local scale.

Sorry we have been drawn so far from the original topic. Yes, science needs to be challenged - Archie Cochrane initiated a complete (ongoing) revolution in medicine. I am quite happy with your paper (but no amount of research let alone one piece ever produces a clear cut, unequivocal answer, in science that is impossible). I am glad you are standing up to the criticism as it is important to accept that your research shows what it does. I just hope that is accepted, but it is built into a management program that accepts the influence of sparrowhawk within the wider food web, and does not attempt to destroy sparrowhawk in an attempt to distort the web.

I have to take issue with you here. I think science can provide clear cut, unequivocal answers, but the important thing is that the answers should be capable of being shot down in flames. I would be fascinated to hear from someone who knows e.g. of a city in Europe where Sparrows have plummeted without a Sparrowhawk influx or vice versa, but the more I look the less I find. On the other hand, the agri-intensification hypothesis can never be disproved, because it doesn’t generate testable predictions. Our hypothesis could well be shot down, but then the improbable degree of correspondence that we discovered between Sparrow decline and Sparrowhawk recolonisation would be an even bigger mystery than the decline itself.

OK. You seem to be challenging the role of agricultural intensification in degradation of biodiversity, that the move from spring cropping to winter cropping is not harmful. I have lived on East Lothian mixed/arable farms all my life, (except two years on a farm near Dumfries), have looked at farms up and down the UK and abroad, and am astounded. The changes in agriculture have brought enormous simplification to ecosystems :
far fewer habitat types;
far fewer species;
far fewer food sources;
far less unimproved ground;
vast reduction in wet/water features;
far higher inputs of chemicals which may or may not have good sides as well as bad (I practice conventional agriculture).
These have been deliberate policies of intensification. It is not good enough to say that these effects are not linked to agri-intensification, they are how agriculture has been intensified.

I’m primarily challenging the notion that agri-intensification caused farmland bird populations to go off the edge in the mid-1970s, which is the ‘emergency’ behind the government involvement and the consequent bureaucratisation of the response. Nobody questions the idea that intensification (more pesticide use, more chemical fertilizer, different sowing regimes, more efficient harvesting/storage of grains, more drainage, quicker turnover in general) has occurred, but I say that the unequivocal statements coming out of conservation organisations to the effect that limiting resources for birds have declined because of these changes are not backed up by evidence.

Now, I see myself in the position of many doctors, astounded that the mechanistic principles they had used for so long could be proved wrong, but they were. I see cause and effect before my very eyes. Your role would be to get on and prove me wrong - please be my guest, world agribusiness surely would be delighted to make you very rich indeed, if you succeed

Really? You wouldn’t have their phone number would you?

I am not saying that other things - urbanization including infrastructure across our rural areas being a prime example - are not important impacts on biodiversity. The challenge is to show that agri-intensification on its own is not an important impact.

Or is that not what you were suggesting ?

Not really! At the risk of opening another can of worms, that would be a bit like proving the non-existence of god. The challenge is to find the variables that best explain the variance at issue. If the explanation (in the statistical sense) is good enough, one can then argue that the variable concerned is the ‘cause’ you are looking for. This would also throw into question any folk wisdom that attributes the variance to a different cause.

 

[spencer f]

Interesting discusion,
I agree that intensive agriculture should not be used as a scape goat but theres no smoke without fire.

I've looked at several related studies and drawn a conclusion.

Ian Newton paper 2004

This was an apprasal of causal factors and conservation action in respect of farmland bird declines. This paper seems to state that although several species have shown a marked improvement since AES's, some have either continued to decline or remained at low levels.

Juliet. A. Vickery 2003

This study suggests an overhaul of agro-environment schemes is reguired, supported by better science and tighter managment.

Robert. A. Robinson 2001

This study concluded that AES's may need to vary between regions because of the association between arable land and certain species.

Mark. J. Whittington 2004

This study discusses the effects of changing habbitat structure on predation risk. This study suggests that predation could be a key factor in bird decline, but only in conjunction with major habbitat change during agricultural intensification.

I find this last one interesting as it supports what I've said before. Predation hypothesis and habbitat destruction go hand in hand. A study that supports predation but dosn't adequately address habitat quality, lets itself down. Equally, the agro-intensification study that does not adequately explain the predation factor, lets itself down.

Chris,
you mention Skylarks, the RSPB website states that highest densities occur in set aside and spring grown cereals, and the lowest in autumn sown crops and pasture. Also that the switch from hay to silage means that grass is cut too frequently for the bird to nest. Do you challenge this?

Its also said, for example that Lapwing have suffered severely from heavy grazing, land draining and silage.

Yes most studies end up saying more study is needed. Of course the study can never end, this is the only way a perscription for a given problem can be developed and perfected. Unfortunately money is at the centre of most things, but it is the way hte money is spent that must be scrutanised.

CPbells hypothesis conjures up images of waves of Sparrowhawks comming in like WWII bomber formations killing every bird in sight.

CPbells study has made me think more seriously about the role of predation in the big picture.

I remember going on a field trip to France as a kid. I was taken back by the miles of mono culture and lack of hedgerows. I remember thinking, how can anything live in such a wasteland.

It is not possible to talk in unequivocal terms when it comes to intensive agriculture. The vast area, the number of species involved and the problems complexity, means that you can only weigh up the evidence and obervations to hand and make an informed judgement.

 

[CPBell]

Spencer - The Newton paper is a summary of the orthodox view ca. 2004, and like most of his reviews aims to present conclusions at their face value rather than looking at works from a critical standpoint. I think I read the Robinson paper some time ago, but I haven’t read the Vickery or Whittingham papers. Thanks for flagging the latter up in particular – give me a couple of days to read it and I’ll give you an honest opinion.

The issue of Skylark and set-aside is a good example of the gulf between theory and practice. When set-aside was brought in it was confidently asserted that Skylark populations would soar, but it didn’t happen. My impression, without having looked at the issue too closely, is that linking Skylark decline with nest destruction through silage cutting may depend to some extent on extrapolation from Corncrake, though I couldn’t swear by it.

Leaving aside formal studies for a moment, I have to say that my own experience of change in the countryside doesn’t really chime with that of some other contributors to the thread. I can remember back to the late 1960s, and I can’t say the countryside that I used to roam about in back then is all that different now. There may well be more chemical fertilizer and pesticide use, and of course there wasn’t any oilseed rape back then, but there are just as many hedges, ditches and rough patches as there ever were. I also grew up in a mainly pastoral area with the odd arable field, and on the whole the same fields are still arable.

I can also remember the effective propaganda at the time as to how the countryside had been ruined since WWII, the great bugbear then being the grubbing out of hedges. The countryside always changes, and bird populations always go up and down, so like the poor the ‘changes in farming cause bird declines’ argument will always be with us.

 

[spencer f]

When I suggested public education on the benefits of native broad leaved species in people's gardens, the then Scottish Environment Secretary said "I am a gardener and there is no way I would tolerate weeds in my garden." OKAY, he wouldn't, but that is no reason why every gardener in the country should not be fed the information and given the choice.
Mike.

This is discraceful. To think that someone in this position could have such a narrow minded view.

This promotes the view that a gardener should not have native plants in their garden. A 'weed' is a plant in the wrong place and not necessarily a native. I am sickened by this backward thinking. This person is supposed to be a spokesman for the environment, these people need to get with the programe and educate themselves on the importance of urban biodiversity, UNBELIEVABLE.

 

[CPBell]

Spencer f – As promised, I’ve had a look at the Whittingham paper. It’s important to bear in mind that this is a conference presentation, and the purpose of conferences is to provide jollies and cheap publications for academics. Peer-review is fairly desultory for conference proceedings.

The paper creates a raison d’etre for itself by stating that there is a polarised debate between advocates of habitat change and predation as a cause of bird declines, but that the authors are wiser than this since they understand that habitat and predation risk interact. We are then treated to several pages of discussion along the lines of e.g. short vegetation is good because birds can see predators coming, but it's bad because it contains less food and predators can see them; big hedges are good because nests are easier to hide and they provide cover, but bad because some birds like to nest in small hedges and predators can also hide in them. There is some pious waffle about how all this proves that varied habitat is best (this is known in the trade as a ‘hand-waving’ argument), and then there is then a classic sign off:

“..change in habitat structure has the potential to provide significant benefits in terms of reducing predation risk and hence enhancing foraging rates, but the crucial question is ‘could it affect population size?’ We cannot answer this question with current data, but if the response is affirmative then targeted habitat management of micro- and meso-scale habitat may be a key part of the design of future agri-environment schemes.”

In other words after being unwise enough to sit down and read this, you’re none the wiser, but I’ve come up with a cute rationale for my next research grant. The reality is that nobody who studies the effect of predation can afford to ignore habitat and vice versa. If they do, their work will be a waste of time and will never get into print (bar conference proceedings perhaps). For instance, our paper (remember that?) discusses the differing effects of predation in urban and rural environments, and the effect of predation risk on habitat viability.

The idea that the answer to bird declines lies in some subtle interaction of change in habitat and predation rates is just another example of the school of thought that says ‘there must be an incredibly complex explanation that will need loads and loads of research going on for years in the future to uncover, hopefully keeping me and my friends gainfully employed until we retire.’ The downside of this is that scarce resources are wasted that could otherwise be invested in work that provides practical solutions to real problems. The lack of any concrete conclusions also means that the discussion can be wound into a rationalisation supporting the orthodox view, and that the study can then be added to the supposedly ‘overwhelming’ evidence in support of the same orthodoxy.

This is how approaches to conservation that are really only based on subjective judgments acquire scientific respectability, so it’s not just harmless flummery.

As I said earlier - an honest opinion, no more, no less.

http://www.cpbell.co.uk

 

[pianoman]

Am seeing many more sparrows in recent years in my area.

About 20 years ago the population plummeted in a very short time, shrinking to particular population centres. In that time I've watched it recover at about 50m radius at a time.

Finally, about 3 years ago the breeding population reached my garden. there was a rapid increase in the numbers in my garden over that time, which has now more or less stabilised. HOSP is now the commonest passerine in my garden.

To me, all that points to a specific event in the past, such as a fairly specific disease perhaps. Since that time it looks like a steady gradual recovery to me.

Not that scientific an appraisal I know...

 

[CPBell]

I've put some material on YouTube for anyone who hasn't made their mind up yet.

 

[captaincarot]

the greatest question raised by this so called research is how long before the gathering of data began were the conclusions written

 

[Motmot]

'I would be fascinated to hear from someone who knows e.g. of a city in Europe where Sparrows have plummeted without a Sparrowhawk influx or vice versa, but the more I look the less I find.'

In the city of Madrid, House Sparrows are also declining a big lot. Sparrowhawks can't be blamed for the decline there. Just an example, many other european cities share the situation.

 

[spencer f]

cpbell

You make a very convincing argument and your study seems pretty sound to me. However I am not sure the situation is so black and white, I feel the re-colonization by sparrowhawks may be inter related with other factors. Many of the large old trees remain in the urban landscape which may favour nesting sparrowhawks, however as I have said before, there have been dramatic changes to peoples homes and gardens over the same time period. I think there is a fear that blaming sparrowhawks may lead to their persacution. The answer must lie in enhancing the habbitat for both birds so they can both thrive.
There is a growing number of observations that suggest that the sparrow population is begining to pick up in many areas. It would be interesting to find out exactly what is causing this. I hope that you get more support for your work because fighting amungst ourselves dosn't get us anywhere.

 

[CPBell]

Spencer

Thanks for the comment on the YouTube channel. I've posted a response there.

Motmot

Thanks also for the Madrid heads up. Do you have a published reference for this?

 

[King Edward]

CPBell,
Assuming you are correct that Sparrowhawk predation is the main cause of House Sparrow decline in towns and farmland, to what extent do you think other factors such reduced food supply and habitat simplification are likely to be a contributory cause? E.g. if the habitat changes mean that sparrows have to spend more time looking for food further away from cover, this may not be a problem in the absence of predators but leaves them very vulnerable when Sparrowhawks are present.

To turn the question around, how much could the effects of increased predation be mitigated by habitat improvements?

 

[spencer f]

Here are some of my personal observations that have brought me to my conclusion thus far.

Nine times out of ten when I've investigated houses with large privet hedges, old dense shrubs or Ivy, sparrows are present. On one 300 yd stretch of road near me 95% of front gardens have disappeared under paving, the small percentage that remain have old established shrubs with sparrows flitting about in them.

Strangely, the only type of conifer I have seen sparrows nesting in is the golden
variety. I've heard that sparrows are particularly attracted to the yellow colour. Does anyone have a different experience, I would be interested to know.

There are cats everywhere, they seem to spend all of their time waiting for some unsuspecting creature to pounce on.

I have dedicated my home and garden to the attraction of a sparrow colony, but the only time I am successful is during the breeding season when members of several colonies converge on my garden for live mealworms. This would suggest that they either find the worms irresistable or they have to travel much further for insect prey.

This summer I observed a fledgling sparrow tweeting inocently on some gravel at the front of someones home. A magpie hopped towards it, the sparrows tweeting got more high pitched, as if it was pleading with the magpie. The magpie briefly looked at it then scooped it up and flew off with it. This is why I cringe when people talk about the beauty of nature. The sparrow has sveral predators, all of which have had a marked increase since the seventies.

I would have to say that no matter which theory is correct, a good thick hedge is key to sparrow success for it can provide protection from predators, invertibrate food and nesting oppertunities. Remembering that not any old hedge will do because it needs to meet certain criteria for sparrows.

 

[earleybird]

I would have to say that no matter which theory is correct, a good thick hedge is key to sparrow success for it can provide protection from predators, invertibrate food and nesting oppertunities. Remembering that not any old hedge will do because it needs to meet certain criteria for sparrows.

Interesting observations Spencer. I have seen great changes in the prevalence of BOP here in Somerset over the past 30 years.

In 1979 I travelled all the way to the New Forest for the day to try to spot a Buzzard without success. Today they are literally everywhere. ! We have Sparrowhawks nesting in next doors garden for the past 4 years .

It is understandable therefore that there is a tendancy to draw a correlation between the rise in prevalence of birds of prey and the decline in the sparrow populations.

My personal observations would concur with yours. I suspect that the decline in sparrow populations may well be linked to the erradication of hedges in the past two decades due to

Increased need for off road parking in urban front gardens (most houses today having 2+ cars)
and in the countryside around fields, where maintenance of hedges and ditches are an unwelcome annual expense for Farmers.

My neighbour planted a beech hedge at the bottom of my garden 12 years ago. It is now 8 feet high a metre thick and 30 metres long . The past few years we have seen a year on year increase in sparrow populations. Last week I took pictures of a pair of sparrows building a nest a thatched roof ..in November !

 

[spencer f]

You are indeed lucky to live in such an environment, I can only dream of such things. In days gone by people had to take precautions to prevent birds from nesting in the thatch. I would be interested to know what species the new hedge consists of. If I were to take a guess I would say hawthorn, but if it were cypress that would be interesting. I feel that peoples personal expieriences are greatly underestimated and would carry great weight in discussions such as these.

 

[spencer f]

Sorry earlybird you clearly state that it was a beech hedge that was planted, I must be tired. Yes here in the city I've noticed that beech is often utilised although they are quite rare in the city nowadays.

 

[CPBell]

Spencerf, Earleybird, King Edward

I've posted a video response - a bit rambling, but I hope it makes some kind of sense.

 

[earleybird]

interesting argument CPBell and persuasive reasoning but speaking from my personal observation I have to say that your supposition that ‘hedges are increasing in the countryside all the time certainly does not apply here in Somerset. It certainly hasn’t been just a ‘post war phenomena anywhere in the South West to my knowledge’ Perhaps Essex and the Home Counties are different !

Here it can be clearly observed that over the past decade or so, arable fields have had hedges removed to increase the size of fields and make them more manageable and economical to harrow,sow and harvest particularly for some of the newer crops like rape for example .Witness the vast fields of rape in Wilts for example

In the past 10 years my work took me into Devon, Dorset, Wiltshire and all parts of Somerset often travelling up to 1000 miles per week and I have never seen any evidence whatsoever of Farmers planting hedges ? I have seen many removed however, particularly in Somerset and Wilts.

To be honest hedges and ditches are a continual nuisance to farmers and the rural community alike. Farmers rarely seem to have the manpower and resources to cut back their hedges and clear their ditches, even to boundaries to public highways. Some of our back roads and droves are almost impassable in the summer months with vegetation from both sides touching in the middle.!

Regarding your comment that there are now ‘manageable environment and wildlife schemes

I’m not sure about the relevance of ‘Councils being concerned about creating green spaces and habitats ? I understood that this discussion was specifically regarding the decline of sparrows in gardens as evidenced by the annual RSPB garden bird count? I do not see how the two vastly different habitats and environments can be considered together.?

There does not appear to have been a similarly dramatic decline in any other garden birds spieces as there has been with sparrows and unless someone can convince me that sparrows are the preferred diet of the sparrow hawk I think that the conclusion that the ‘decline in sparrow populations is due primarily to sparrow hawk predation’ has yet to be proven .

 

[King Edward]

Quote from video response by CPBell: "we have found a solution to this problem"

Could you explain what you mean by the word 'solution'? Do you mean simply that you have explained the cause of sparrow decline, or that you have found a way to reverse it (e.g. Sparrowhawk removal)?

Regarding hedges and rural habitat, a lot of the hedges round here are 'managed' by aggressive flailing, especially in the more arable areas. I don't think there has been that much recent change in total hedge length over the last century, but I'm sure their suitability for birds and other wildlife has declined substantially. You just can't equate a kilometre of neatly flailed hawthorn hedge, surrounded by autumn ploughed and sown intensive arable monoculture on either side, with the same length of good quality hedge surrounded by seed- and insect-rich habitat.