The following was a recent comment posted by Jit at my Birdageddon article. It is reproduced here in full, since it serves as a worthy article in its own right.


The story goes like this. Puffins are stubby little cute things. They eat tiny fish called sand eels. The eels are declining owing to climate change. Climate is changing because human civilisation is emitting more CO2 than the Earth can handle. Because of this, we’re really worried about the puffins and we have to change our ways.

Of course you would not be surprised to find that there is more to this than meets the eye. It is probably true that should sand eels decline for any reason, then puffins will suffer. (Puffins do not always major on sand eels, and this varies by location and time of the year.) The puffin is an iconic bird. It’s one of three on the cover of my copy of Peterson (the other two are a hoopoe and a lapwing).

The first question I suppose is, are sand eels threatened by climate change? JNCC thinks so, & they are not alone. [Note: puffins are also said to be at threat from increased storminess; a “wreck” a few years back was blamed on climate change. Nevertheless, there is a long history of wrecks; but I can’t definitively say that climate change won’t cause more storminess.]

In another thread, Vinnie Burgoo mentioned a paper by Wanless in 2004. (For someone I presume is not an ecologist to pluck a memory of this paper out of the ether is impressive.) My memory of Wanless et al 2004 is that it made quite a stir at the time, and that I didn’t believe the results (my memory may be faulty; I certainly didn’t believe the results). Wanless et al measured the lengths of innumerable sand eels at a sand bank call Wee Bankie off the Firth of Forth (relevant to foraging by the Isle of May puffin colony). They had data from ’73 to ’02, and over that time the average length of a sand eel had declined by 20%. In terms of mass and therefore nutritive quality for a chick, this decline was larger.

A fishery started in the area in 1990 and persisted until 2000, when it was curtailed over fears for the puffins. But according to Wanless et al, this was not the cause of the decline, which was more likely due to environmental factors. To give them credit, Wanless et al did not pin the blame directly on warmer water, as has been done since. Indeed they mentioned that sand eels might shrink if the water was too warm or too cold.

Simply increasing temperature could not by itself shrink the sand eels. Fish are dependent on the temperature of the water for activity and metabolic levels. If the water gets a little warmer, sand eels grow faster, not slower… so long as there is enough prey to go around.

So now we have to rewind to Fromentin & Planque 1996 where it was noted that one of the key prey items of the sand eel is affected by the North Atlantic Oscillation. This beast is a planktonic copepod called Calanus. There are two very similar species in the North Sea (I think there is a third species found further north). Calanus finmarchicus is more abundant when the NAO is in its negative phase, and Calanus helgolandicus is more abundant when the NAO is positive. When the NAO is positive, there are more westerlies. The surface of the sea is more mixed. The spring plankton bloom is delayed. This favours helgolandicus because its reproductive timing is later. This may also explain why helgolandicus is less nutritious prey for sand eel larvae.

So the picture is now: carbon dioxide goes up. NAO trends positive. Plankton bloom delayed. Less nutritious species of zooplankton dominates the community. Sand eel larvae perform less well. Young sand eels settling into the sand are smaller, and don’t catch up. Puffins have to catch more sand eels to feed their chicks. We’re still worried about the puffins.

What happened next? To their eternal credit, Wanless and colleagues kept collecting data on sand eel lengths. And after a couple more years of continued shrinkage, the trend reversed and the eels started to grow again (although average sizes are not yet back to 1970s levels).

I was not inclined to believe the NAO story. There was another rather obvious potential driver of sand eel shrinkage: fishing. The North Sea sand eel fishery has risen from nothing in the 1950s to levels of up to a million tonnes in some recent years. Such a cull does not just affect population size. It also exerts selection pressure: the biggest predator is now the net. Thus if an eel waits too long to reproduce, or until it has reached a certain size, there is now a better chance that it will never reproduce at all – it’ll be in someone’s fish cake. And while the local fishery lasted only from 1990 to 2000, a species with planktonic larvae has its genes “sieved” over a much larger area. Fishing pushes reproduction to happen earlier at smaller sizes. And as you might expect, fishing at this scale has also reduced the spawning biomass of sand eels. This happens a lot with fisheries. Fish stocks are treated as infinite, since most (bony) fish have very small eggs and lots of them. Then at some point recruitment falls.

What is normal? We hear a lot of doom and gloom about puffins. And compared to the pristine world before human civilisation, they are obviously less common. But you don’t have to go back too far to find times when they were less common than now. The Isle of May was mentioned above. In the first half of the twentieth century it had a handful of breeding puffins. That number is now about 40,000 “apparently occupied burrows.” They were helped by a cull of 30,000 gulls in the 1970s (it couldn’t happen now). But my own suspicion is that the initial growth was helped by immigrants from down south. At the time grey seals, because of new protection from hunting, were thriving in the Farne Islands. Low lying puffin nests were crumbling. The soil was eroding. Those refugee puffins may have made their homes at the Isle of May.

In historical times St Kildans, as well as using puffins to flavour their porridge, exported the feathers of tens of thousands of the poor blighters to form decorations for women’s hats. On Lundy (“puffin” in Norse) Island, rats saw to the demise of a colony, as they did on Ailsa Craig after a shipwreck (both colonies probably >100,000 pairs).

I find it interesting that we are inclined to blame the terror of the day for all our ills. So soon we forget the carnage of the past. And conservation flips from saving animals and plants in the places they live to trying to save everything at once by cutting carbon dioxide emissions.

At least, unlike for kittiwakes, I don’t expect wind farms to harm this particular species of bird.


  1. Point of information:

    Sandeels are processed to form the main food of farmed salmon. Also in, Denmark, they are fed to farmed mink, though whether that will continue I don’t know.


  2. Nice post. Most environmental issues seem to be complex, and proposed CC as main causation usually way too simple. “I find it interesting that we are inclined to blame the terror of the day for all our ills.”

    The list of things blamed on climate change must be immense by now (and mostly ridiculous). The website keeping track had to bail out years ago because it was just too much work. Covid may have slowed the accumulation of new blames, but of course a number of sources have recently tried to pin covid on the ills of climate-change too. Hence it could capture an entire new pyramid of blame all in one go 0:


  3. Wikipedia tells me that another alcid, the Great Auk, is believed to have suffered its initial decline from climate change (warming after the Little Ice age allowing more predation by polar bears), but of course the final coup de grâce was by humans wanting to fill their pillows with feathers. What an ignominious end.


  4. @ Bill I was being a bit flippant when I mentioned fishcakes. I thought sand eels were put into animal feed, but mink hadn’t crossed my mind.

    @ Andy a lot of species passed through a bottleneck at an earlier stage of our civilisation. Some did not make it through. This was the time when we killed everything we saw and ate everything we killed. And it is not so long ago that we became wealthy enough to feed everyone and clothe them without behaving like that. Things should be better now, which makes the many wind farms built/being built/planned for the North Sea so disappointing. It does not seem rational to kill biodiversity in order to save it.

    @ Alan, that wiki page is heart wrenching. One species that did not make it through the bottleneck I mentioned above was the original penguin. Quote:

    “The last pair, found incubating an egg, was killed there on 3 June 1844, on request from a merchant who wanted specimens, with Jón Brandsson and Sigurður Ísleifsson strangling the adults and Ketill Ketilsson smashing the egg with his boot.”


  5. Jit,

    “At least, unlike for kittiwakes, I don’t expect wind farms to harm this particular species of bird.”

    Of course, the RSPB would claim that they are doing it for the kittiwake. After all, the death toll due to wind farms is small fry compared to the kittiwakes that the farm will save by preventing global warming:

    However, quite apart from the uncertainties regarding collision modelling, there is also the question of how much the decline in sand eels is due to fisheries rather than global warming, and how much global warming can be avoided by a windfarm anyway, and hence how many kittiwakes a windfarm could save. Even if such a calculation could be made, I’m reasonably confident its results wouldn’t make a case for the net benevolence of windfarms as far as the kittiwake is concerned.


  6. @ John of course the “benefit” of the wind farm is spread over the entire globe. It is likely to be immeasurably small. The cost, meanwhile, is local (there may be other remote costs in mineral extraction/refining/manufacturing that we don’t know about). In principle we can estimate the costs. That may include 73 kittiwakes plus or minus quite a few. I don’t see a world where an accounting of the costs and benefits ever comes out in favour of the wind farm.

    If you read the ornithology chapter of the environmental statement for Hornsea 3, you find a table of potential effects on birds that stretches for 10 pages. It covers collision risk, disturbance in the construction phase, displacement of foraging… for each of more than 100 rows, the significance of the effect is summed up as: “not significant in EIA terms.” A cynic might call that a predictable result.


  7. Jit. I have heard of the bottleneck explanation before but have questioned it. It seems to me that it flies in the face of increased demands placed upon nature as human populations spectacularly exploded and found new ways to live. It does not explain why the North American megafauna perished in lands with low numbers of largely nomad inhabitants, compared with the survival of the African megafauna in lands with sometimes denser human populations. Also as technologies advanced, more and more pressures were exerted. For me, one of the most memorable parts of the “Out of Africa” film was the second flight taken by Karen Blixen when she flew over formerly pristine grassland now scarred by truck tracks, symptomatic of greater stress being placed on the area by humans.

    Now, naturally declines in species numbers and diversity is laid at the door of climate change/chaos/whatever, which is all our collective fault. Species are disappearing before we even find them. We are evil.


  8. Jit,

    Yes, that’s the problem with wind farm decision-making — global benefits are offset against local impacts. I say that if you are going to predict the species-specific deaths caused by a specific wind farm, you should restrict the calculation of lives saved to that same specific windfarm. Incidentally, I’ve just taken a look at a wiki article talking about the commonly held criticisms of EIAs. The list is predictable:

    a) They do not take sufficient account of global and indirect impacts
    b) The uncertainties are nearly always underestimated (judged by after-the-fact assessment)
    c) They need to take matters of environmental justice more seriously

    I’m not sure about environmental justice. It’s just too wooly a concept and provides the perfect excuse to over-ride scientific results.


  9. John, knowing your interest in collective nouns, I thought you might be interested that one applied to puffins is an “improbability”. I am charmed.

    Liked by 1 person

  10. @ Alan I cannot definitively prove the bottleneck applies everywhere. Indeed it does not. But my assertion is that there are species that went extinct that, if alive today, would be safe, & that this is purely owing to a reduction in pressure from humans. If you are ever short of reading material, I recommend WH Pearsall’s Mountains and Moorlands, a very old book in the New Naturalist series. In it can be found this list of “vermin” trapped in Glen Garry, Inverness-shire, between Whitsunday 1837 and Whitsunday 1840:

    11 foxes
    198 wildcats
    78 house-cats “going wild”
    246 martens
    106 polecats
    301 stoats and weasels
    67 badgers
    48 otters
    15 golden eagles
    27 white tailed eagles
    18 ospreys
    63 goshawks
    275 kites
    63 hen harriers
    5 marsh (probably Montagu’s) harriers
    98 peregrines
    9 ash-coloured hawks (?male hen harriers)
    11 hobbies
    6 jer falcons (gyrfalcons)
    7 orange-legged falcons (?red-footed)
    78 merlins
    462 kestrels
    285 common buzzards
    371 rough-legged buzzards
    3 honey buzzards
    475 ravens
    1431 crows
    71 fern (short-eared) owls
    35 horned (long-eared) owls
    3 golden (tawny) owls

    And this is just 3 years in one estate. Several of these species are no longer to be found in Scotland, or have been lately re-introduced.

    I don’t know about the large mammals of North America. For certain other factors were in play. But we were a bottleneck for many species, and in many parts of the world, we still are. How many species will not pass through is a different question.


  11. @ John sometimes an EIA is relatively easy and the results are fairly objective. If a habitat is to be destroyed it can be given a value and the loss is easy to establish. Things become vague with wind farms and other developments when the effects are not absolute. To take the wind farm example, our evaluation of the habitat is based on boat-borne surveys of birds foraging or passing through. But how accurate is this, and how variable is it over time? Next we need to estimate the damage to our estimated ecological asset. But things soon spiral away from numbers that can be justified robustly. Soon we have “73” kittiwakes predicted to die on the blades every year, or else the assessed impact devolves into phrases like “a low impact on a highly sensitivity receptor with a resulting non-reversible minor adverse effect (not significant in EIA terms).”

    To be fair to ecologists, we all know that trying to make an objective measure of the value of habitats and the harms of development is quite important. But it’s one thing to know we need a good measure and another thing to find a way to do it.

    Liked by 1 person

  12. But Jit, isn’t there also the paradoxical fact that if a project has been approved that will cause environmental damage then the fact that part of the affected area has previously been given protection renders it more likely to be affected? The protection means that the land cannot be “developed” thus it has a low economic value.
    I recall this situation being explained to me as a schoolboy after I discovered a pond adjacent to Epping Forest had great crested newts within it. I was told that concealing this occurrence was a better policy than trying to get the pond protected. I didn’t really believe this at the time, but then I found brachiopods in flint pebbles and geology claimed me.


  13. Alan, great crested newts are now protected in law. Thus, if you had two farms, each with a pond, and one pond had great crested newts and one did not, that would certainly affect the relative appeal they would have for a developer. To develop the farm with the great crested newts would probably require a licensed ecologist to collect all the newts and translocate them to a suitable receptor site, maybe one you had caused to be made, with associated time delays and expenses. Then you would have special fencing to stop the newts from returning to their old haunt. And you would have to take special care around any relevant terrestrial habitat. Under these circumstances, the wildlife-friendly farmer would lose out compared to the farmer who long since wrecked their pond or allowed it to silt up.

    Of course most housing development is on arable land these days. This is the path of least resistance, because ecology-wise, it’s already mostly ****ed.


  14. May I just say how pleased I am to see this thread here. Probably the main area of my scepticism with regard to climate change isn’t in respect of the science behind it (after all, I’m not a scientist) but instead is with regard to the vast ecological damage that climate warriors are prepared to inflict in the name of “saving the planet”. And they claim to be “green”. That makes me angry.

    Liked by 2 people

  15. This is an attempt to repost, having erroneously posted it in the Walking in the Air thread

    Jit, I believe that as long ago as when I was a teen (1950s = Early Miocene) those newts were protected and considered a relatively rare and declining species. My suspicions then was that the advice to keep stum itself would offer the newts more protection than seeking to protect the location.

    I have also been involved in the creation of two Parks, one National (Long Grass Prairie), the other Provincial (Clearwater Valley) in Saskatchewan. For the Prairie Park provincial mineral rights had to be transferred to the Federal Government so needed to be evaluated (in this I was involved). Those resources would essentially be sterilised. The Clearwater Valley I geologically mapped and was struck by its beauty. I suggested the area be conserved as a protected park. The only objectors were trappers (but the area had essentially been trapped out and during two months camping there, we saw no mammals) and those supplying Uranium City overland during the depths of winter (when no one in their right mind would visit the valley, even assuming they could). What we became aware of was, in both instances, that we were essentially destroying the economic value of the land we were assessing.


  16. Alan, not to get squishy, but economic value is entirely human-centred. What value has a pristine rainforest? Probably none, and it has always riled me when conservationists try to justify protecting such places “in case there are new medicines there” or similar. We should protect such places because we can.


  17. Jit indeed, squish away. I promoted the Clearwater Valley because it was beautiful and I thought it should be preserved without change so that others might marvel. For me it was beyond value. I am so very pleased that other people well before me thought similarly so now we have the near-pristine wonders of Yellowstone, Glacier and Zion (amongst many others) to amaze and stupefy.


  18. Alan Kendal:

    “Jit. I have heard of the bottleneck explanation before but have questioned it. It seems to me that it flies in the face of increased demands placed upon nature as human populations spectacularly exploded and found new ways to live. It does not explain why the North American megafauna perished in lands with low numbers of largely nomad inhabitants, compared with the survival of the African megafauna in lands with sometimes denser human populations.”

    Funny I’ve just read a paper that suggests that elephants became extinct in what is now Israel because of predation by Homo erectus. There is also a summary on


  19. @ Bill animals with a long lifecycle are particularly prone to population declines from hunting. Elephants fit that bill nicely. You have an animal that matures after ten years, has a two year gestation and gives birth to one calf (and half of all calves are males). You don’t have to kill many to set a decline going.

    Seabirds are similar in some respects. Taking puffins: a single egg, long-lived adults. The mortality of young birds is high; after surviving for a year their chances improve, maybe through experience (the opposite of Bomber Command crews). I think the losses of breeding adults in birds like kittiwakes must be much more significant than losses of chicks/young adults.

    Re: Iceberg A68a. A couple of weeks ago this ‘berg was in the news as “bearing down” on South Georgia or similar. Penguins were in peril.

    Since then, nothing. I thought this must mean that the danger has passed, if there was danger at all. Searching for news turns up naught either. But NASA’s Aqua and Terra are still sweeping by. It looks like A68a’s finger snapped off on about the 23rd of December. By that time it had already passed its closest approach to South Georgia (so far; c. 100 km) and was swinging south. Today it is 150 km ish away, but is closer than it has been. It seems to be swirling about a bit. So perhaps it’s too soon to call the peril of the penguins as past.

    Dunno if this link will work:


  20. JIT: I think the point I was making about the elephants was that the extinction happened 400,000 years ago and an earlier hominid was responsible.

    Getting back to seabirds. It seems likely that the great auks were replaced by fulmars, at least in British waters. Fulmars first nested on Foula in the 1850s, and on St Kilda at least 50 years before then.


  21. @ Bill I think there is strong competition on cliffs for nest sites, so one species’ loss might be another’s gain. That’s why the kittiwake towers mentioned in the other thread might help. Of course, they’ll have to resist gulls or the whole exercise would indeed be pointless. (I suppose the towers will only work if there are excess kittiwakes unable to breed because of the lack of space. But I’m sure something will make use of them.)


  22. A68 update, for anyone still following this thread:

    With apologies for the verbose report and for straying slightly away from the subject at hand (but climate change’s tendrils do reach into this miniature of terror).

    To recap: A68 snapped its join with Larsen C in July 2017. It wandered about a bit, then a couple of months ago began to make a bee-line for South Georgia. I began following its progress in the news, and then when the news went quiet, using NASA’s handy Terra/Aqua photos.

    November 4 2020, press release, BAS.

    If it becomes grounded near the island, it could cause disruption to the local wildlife that forage in the food-rich ocean.

    The story was immediately spread far and wide. The wildlife at risk idea was a major focus of the news reports. On November 7 the “Independent” online had a story about record melting of the Larsen C ice shelf, and joined the dots between climate change, such melting and wildlife in peril on South Georgia. The story goes: Melting of Larsen C is worse than we thought, this could lead to the ice shelf collapsing, and “as we have seen with A68 drifting towards South Georgia, icebergs heading north can pose a threat to wildlife.” (Quote attributed to Suzanne Bevan of Swansea U, lead author (I think) of the article about the record melting of Larsen C.

    David Bressan of Forbes said this on November 12:

    Biologists fear that the island ecosystem could be seriously disrupted if the iceberg runs aground into the island’s shallow waters. In addition to injuring animals during the collision, the iceberg could block the normal feeding and foraging routes that the animals use during their crucial chick- and pup-rearing seasons.

    Injuring animals during the collision? How fast is this berg the size of Cyprus moving? Feeding and foraging routes?

    Earthsky, December 20:

    Penguins and seals need access to the sea to feed so the iceberg could easily block their foraging routes and life on the seafloor could be crushed if the berg grounds. The fear, according to ESA scientists, is that if the berg does anchor against the South Georgia coast, it could remain there for up to 10 years.

    This is partly wrong of course, and I’m sure the Earthsky folks are really upset at the thought of a few sponges and stuff getting ground to paste by A68. The wrongness is that there was never any hope, or fear, that A68 might hang about for a decade in the shallows off South Georgia. (It’s at about 54 and a half degrees S, an equivalent latitude to Whitby.) The fear of a decade’s stay might derive from iceberg B9 that washed up at Commonwealth Bay (?25? years after calving from a different ice shelf) and hung about there causing the poor little penguins to have to make an unusually arduous journey to find actual water.

    Anyway, A68 broke up on about December 23. The BBC said “Giant Antarctic iceberg A68a is not done yet” – but then there was no news for a time. As mentioned, after a couple of weeks of silence I hunted for news and when I could not find any I hunted for data, finding the NASA EOSDIS page. By January 17, A68 was 200 km from South Georgia and the danger seemed to have passed – hence the ongoing lack of news. But it then began to drift back towards the shore, and a couple of days ago it was about 135 km away…

    Today’s BBC reports that a further break up has occurred:

    Towards the end of last year, A68a looked from space like a huge pointing hand. Its still significant bulk prompted fears that it could disrupt life on South Georgia should it become grounded just offshore in shallow water.

    The concern was that the presence of such a large obstacle might disrupt the foraging behaviour of the island’s many penguins and seals.

    With the latest disintegration event, the danger of this scenario seems to have passed.

    A major question now is whether the scientific expedition that was aiming to study the iceberg will have anything left to observe by the time it arrives on site.

    Liked by 4 people

  23. Alan, I was tempted to make comparisons between the sizes and shapes of the life forms found resting on the shorelines of Whitby and South Georgia, but refrained from doing so.


  24. Re JIT Larsen c Ice shelf melt report.

    A68 ‘might’ (x11) …

    ‘ çould’ (x17) …

    ‘íf’, and it’s a big ‘IF ‘ (x55.)


  25. ” interesting that we are inclined to blame the terror of the day for all our ills.”

    So the demise of the sand eels must be due to Covid 19.

    But wait ! didn’t someone say Covid 19 was a result of CO2 & I ran my gen-set in yesterday’s power cut, so it was me who killed all the sand eels & caused Covid …

    … sorry ! ☹

    I’ll just grill a few more Puffins on the BBQ tho cheer myself up 😀

    Liked by 1 person

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