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Do not disturb: Life with the puffins

Updated Tuesday 15th June 2010

In an extended interview recorded by the Saving Species team, seabird biologist, Mike Harris, shares his experience of studying puffins on the Isle of May. Is climate change to blame for a 30 per cent decline in puffin population?

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Copyright The Open University


Mike Harris: I’m Mike Harris. I’m a seabird biologist and I must have one of the best jobs you could imagine in this world.

Particularly, on a glorious day like today we’re sitting on the Isle of May National Nature Reserve in the middle of the Firth of Forth, a very famous site for its seabirds and a place I know that’s been attracting you for many, many years. But it’s one bird in particular that’s been a fascination for you, for your life really hasn’t it?

Mike Harris:
Yeah, I suppose, I’ve more or less earned a living from the puffin since the time I started this study. I was saying I was working in Galapagos, I came back to this country in 1972, and I hadn’t got a job, and I saw this job advertised. And it was a job to look at puffins in Britain to try to decide why the numbers had declined so dramatically. So I applied for this job, and I was working on St Kilda in those days, but we needed a colony where puffins were doing very well.

St Kilda was great. It’s a nice island and the puffin population collapsed, and we were looking at that. But I needed to know how well puffins could do given a chance. So I looked around and I found the Isle of May, which was one of the few places in Britain where puffin numbers were increasing dramatically. So the idea was to look at the biology of the puffin and the declining colony and an expanding colony.

The Isle of May hasn’t changed but the political background in a sense has changed. You’ve been through a whole variety of different organisations haven’t you, the changes in how science has been approached?

Mike Harris:
Indeed. Well, I came in ‘72 and conservation organisations were really reorganising themselves. The research organisations, the Natural Environment Research Council was then part of a nature conservancy. They were split off and the money was given to the Conservation Agency, and they were contracted under a thing called the Rothschild Report to get people to do research which the Government thought was needed.

Presenter: The puffin is obviously a bird that’s hugely popular with the public, but from your perspective to have occupied your mind for this length of time there must be all sorts of fascinating stories about puffins for you still to be working on them, whatever it is, 38 years after?

Mike Harris: One doesn’t like to work it out does one? I must say I haven’t worked on them all the time. Well I’ve kept going on puffins, but we have done a lot of other things. The effect of the oil industry on seabird populations, effect of pollutants on seabird populations, fisheries, and now it’s climate change, but puffins have always been there ticking away in the background. And to be honest after five and six, seven, eight years of detailed research on puffins I hate to say it but I got bored with puffins. But now that things are changing in the puffin world, we’ve got all this backlog, this important data, and we can find what’s going on now and set it in an historic context. So I have looked at puffins, but it hasn’t occupied my whole life - I hope.

But the data that you’ve accumulated over all those years is now becoming very important?

Mike Harris:
Yes, we’ve followed the survival over winter, over this period, what food they’ve eaten, how well they’ve grown, the size of the fish they eat and all those sorts of things. And these are the important data which you need to interpret, be it the effect of the oil industry, be it pollutants or be it possible climate change. So we now have an ideal setup to look at changes in seabirds on the Isle of May and specifically the puffin.

So tell me what changes have happened to the seabird population in the Isle of May over the time you’ve been studying them?

Mike Harris: Well let’s stick to the puffin because I know that best. In 1950s there were about five or ten pairs of puffins on the island. They nested on the cliffs, just in cracks in the rock, and this was because the island was - it was farmed, there were sheep on it, there were lighthouse keepers and their families and pets, and puffins can’t cope with that sort of disturbance. They can’t, they never occur on islands with ground predators, for instance. Then things have changed, the lighthouse keepers’ families left here in 1972, the keepers left in the mid ‘‘80s. So now it’s gone from disturbance to more or less complete protection.

So it’s a fantastic place to be a puffin; there are no ground predators; there’s protection. On the other hand, if you’re going to increase in numbers, and we increased from five pairs then to 2,000 pairs in 1972 when I started up to about 80,000 pairs in 2003, you’ve got to have a lot of food. I mean you’ve got to have a hell of a lot of fish however small a bird that you are. And there seems to be profound changes in the North Sea where man removed all the large fish – the large cod, the haddock and those sorts of things – for human consumption. And the numbers of small fish increased and this allowed the seabirds to increase. You’ve got a lot of big fish that are of no use to seabirds, they’re just too big. I mean puffins will only eat fish up to about 20 centimetres long. Anything bigger than that is safe from a puffin.

So are you saying, therefore, that the increasing numbers that you saw up to 2003 is actually partly a symptom of man’s mismanagement of the sea, a result of overfishing that has allowed the puffin population to increase?

Mike Harris:
You might say that, depends from what perspective you come at it, but you’re absolutely right, and it’s silly to get too carried away, and puffins have now declined by about 30% in the last five, six, seven years. But we’ve still got a hell of a lot of puffins and, you know, we shouldn’t get too carried away by this, and we’re now interested in what’s caused that decline of course. I’m not worried about the future of the puffin. People like to think the puffin’s going to become extinct. I don’t preach that at all. But I am interested in what has caused this sudden change in the puffins’ fortunes. We’ve lost 30%, we’ve still got 40,000 pairs of puffins, but why have we lost this? Is it a wakeup call that things are going on in the open sea that we can’t get at any other way?

I’ll come back to that in a moment but the one thing that we missed in that story, we talked about puffins on the Isle of May, what about puffins elsewhere in the North Atlantic, have they been having good times as well?

Mike Harris:
Up until fairly recently, yes. I mean numbers did decline a hundred years ago. You know, tremendous numbers must have disappeared somewhere. But in the last thirty, forty, fifty years numbers in the North Atlantic as a whole have probably remained more or less stable. There’s been some reorganisations, some places have been colonised. The North Sea had very few puffins before and now has a huge number. St Kilda’s numbers declined.

The main centre of the puffins’ world is Iceland, which has two or three million pairs, and we don’t really have any accurate estimates of the numbers there because they’ve got thousands of colonies and relatively few ornithologists. It takes us just to count the Isle of May, to do a population count, which we count holes in the ground, that takes four or five of us three or four days, and that’s for a colony of let’s say 50-100,000 pairs. You can imagine trying to count a million pairs, you know, it just doesn’t bear thinking about.

Presenter: And this is because puffins don’t cooperate with you really. They’re spending a lot of time down burrows aren’t they?

Mike Harris: They’re either down burrows or out at sea where you can’t see. One of the reasons, I must come back to this, I got slightly bored with puffins because you couldn’t see what was happening to them, and I got more interested in guillemots, which sit on open cliffs and you can see what’s going on.

So how do you set about counting puffins and how do you set about assessing how they’re doing down those burrows?

Mike Harris:
Well, to count them we, as I say, we just walk back and fore, back and fore across the island, early in the year before the vegetation has grown up. The puffins have come back after the winter; they’ve been away for six months. They’re cleaning out the burrows, they’re scraping the entrances, and you can see. And so we walk back and fore, back and fore, and then I check down a fairly big sample of these burrows to find out what’s down them. Are they actually puffin burrows or could they be rabbit burrows? Are there two entrances to one burrow? Have you counted the hole in the ground which looks like a burrow but it’s a rock - so you’re over counting in some ways and undercounting in others, so you adjust your count.

And that actually means, you know, reaching your arm down inside the burrow and presumably being pecked by a puffin for your trouble?

Mike Harris: No, we do, well, no, we don’t go to quite that length, but you can tell from droppings inside and that sort of thing.


Mike Harris:
Then, to follow the - how puffins are doing, when the puffins have laid, we do exactly what you said, we lie down on the ground and we have a short bamboo and you can feel down a puffin burrow and with a little practice you can feel an egg. We don’t disturb the puffin, we just, and there’s an egg in that burrow, we say. We then put a stake by it, and we don’t interfere with it at all until the chick’s about to fledge, which will be about, well, the incubation period is, and the chick period together, we’re talking about some oh, two months or something. We go back when the first chicks are due to fledge, and we then feel down.

So we don’t disturb the puffins at all from that point of view. Because if you do you might interfere with the nesting success because they don’t like things going on down burrows; they don’t like to be disturbed. So we can just get a nesting success for that. And we weigh a series of chicks to get a growth rate, and we collect samples of fish, and we watch and see how often they’re fed. So we do have a pretty good grip on what’s going on inside.

Yeah. And you’re able to follow individual puffins from year to year, are you able to see how they’ve done over the winter?

Mike Harris:
Yes, we do. We follow about 200 individually marked puffins with colour rings on, and every year we clock them in and see who’s there, and they do survive very well. Normally about 90 to 93% of puffins survive from one year to another. They don’t breed until they’re five or six years old, but then they survive very, very well and your average breeding puffin probably lives about 25 years. And the oldest puffin we have here – I say we have, I’m not sure we have at the moment – it was ringed as a breeding adult in 1974.

We last saw it two years ago in 2008, which makes it, we know it for 34 years, it’d have been five years old at least when we ringed it, so that was 38, 39 years old. We haven’t seen it for two years. But as puffins get old, a bit like humans, they become slightly, they senes, old age creeps in. They sort of stop breeding, they don’t come back that often, so you don’t see these very old puffins very often. But it could still be there but that’s not the oldest puffin. The oldest puffin known is a Norwegian one which was found dead 41 years after it had been ringed.

Presenter: Good grief, that’s amazing.

Mike Harris: Yeah, it would be a lot older than most of the students we ever see out here.

So I’m just trying to work that out. If they don’t breed until they’re five, but the average puffin lives twenty-five years, that’s 20 breeding years? Is that right, they breed every year?

Mike Harris:

And is it one chick or more than that?

Mike Harris:
No, they only ever lay one egg a year. If they lose that egg, soon after they lay another one. But breeding success is very good because they’re safe down burrows, and as long as there’s enough food for the chicks, they’re all right. They’re safe down burrows, which means both adults can go away and find fish for them. Whereas if you’re like a guillemot you’re nesting on an open cliff, one adult’s got to be there to protect the chick all the time.

But that means that over their lifetime two puffins could be producing getting on towards 20 chicks, which presumably allows them the capacity for the population to expand dramatically?

Mike Harris: Oh yes, this population expanded at about 11% per year for 30 to 40 years. Which is bloody good going for a bird which doesn’t breed until it’s five or six and only lays one egg. Even the chicks survive very well when they go to sea.

Presenter: But you were saying in the last few years the picture is of a declining population, and you were talking about trying to understand why that decline was happening. What sort of lessons are you beginning to learn about that time?

Mike Harris: Well, we did a count in 2003, and we came up with this sort of 80,000 figure. And the population was going up about 10%. So when we did the next count, which was 2008, we fully expected there’d be about 100,000 pairs at least. In fact, when we did the count there were 43,000 pairs. So it hadn’t gone up it had come down by about a third. We now, we then went back and looked at our survival figures, and we now understand there were two winters where survival rate instead of being at about 90% would have been about 60 to 70%, and it’s knocked a hole in the population.

Because puffins are such slow, they do things very slowly, they breed at their old age and then they carry on just with one egg. If you lose adults you can very quickly reduce your population. What puffins can do, if they don’t rear any chicks for four or five years even, the population isn’t going to change very much because you’ve got all these immatures coming along - but if you lose your adults, you have a crash. And we now know that there were two winters where we had these crashes, and the last two winters following that survival has been much better again.

Presenter: And over the winter they’re not here in the Isle of May?

Mike Harris: No, they disappear out into the open ocean. Well, from here they leave mostly the first week of August, and they don’t come back again until middle of March, and up until recently we’ve had very little information about where they went. What we did have was ringing recoveries, and you only get those when they get washed ashore and those are just around the coast. You never, I say never, virtually never, see a puffin from land during the winter - they’re out in the open ocean, and they don’t occur in flocks; they occur in very low densities.

There are one puffin per, I don’t know, one, two, three, four, five square kilometres of ocean, so you just don’t see them, and so we knew very little about them. But modern technology has sort of come to our aid, we now use geolocators, which are very small devices, which we can attach to the rings of the puffin, and we put those on one year, we catch the puffin again and take the logger off and download the data. These give us an approximate fix to where the puffin is every day. It’s not that accurate; it’s +/-100 kilometres. But we’re talking about a bird which will go maybe 1000 kilometres during the winter anyway.

So we now are building up a pattern of where these puffins are wintering. And the interesting thing is that the first year we put them out, we put out 50 of these devices, and I would have normally expected to have got 40 back the next year because that’s the survival rate, and you can’t catch every puffin anyway. In fact, we only got 14 back and we were dreadfully worried that we might have interfered with the bird in some way. But this was the first year that we had this really poor survival of adults, and there’s now no evidence at all that there was any difference in the survival of the birds with loggers and birds without.

So we had some interesting results, but it was in a very unusual winter, and linked in with this, whereas we’d always thought before that our puffins stayed within the North Sea, some of these 13 puffins, 10 of them made a visit out into the open Atlantic. They stayed out there for a matter of weeks, but by the end of December they came back into the North Sea and joined the three which never left, and they did then spend the winter in the North Sea. But we’re now very interested in why these birds went into the Atlantic, and was this “exodus” tied in with the poor survival. Not the ones we got back of course because they survived; if they died, we didn’t get the devices back.

So we’re now redoing that work again this winter, we’ve got more devices out, or last winter should be because we’re not in the spring, and we’re just trying to get these devices back now. And we know survival has been very high over this current winter, and we’re now desperate to find out where these puffins went - did they stay within the North Sea in a good winter?

And when will we have these results back?

Mike Harris: Well, we’re starting to get the devices off now. The puffins are back so we can start catching them and get the devices off. You then put them out and let them stabilise in the local conditions, and we’ve got to take these back to base and then download data. Whereas once upon a time you had very few data, now with modern technology, either technology doesn’t work, or you can’t catch the bird to get it back. But if you do get it back you get an enormous quantity of data, and it now takes days and days and days to process this to actually to understand what it means and to get your map of these positions. So we would hope to know that probably by about August I should think.

Presenter: So if we talk to you in sort of August, September time?

Mike Harris:
Come back and we’ll give you a progress report indeed. Which brings us of course having said all to that - well you will ask me I’m sure - well what next?

Yeah, absolutely.

Mike Harris: Indeed. Well, it’s difficult to know because prediction’s always very difficult. The puffin is a cold water species. It’s, as I say, Iceland’s the centre of its range. It’s called Fratercula arctica. So perhaps it wouldn’t be surprising that if the seas continue to warm up, and they are now warming up, this puffin will get into some sort of problems. Not because the water’s warm but because its food will change, I’m sure. So you might expect at the fringe of the range, and Britain is at the fringe of the range, you might get some change, and the change is going to be less puffins, I suppose. So the prediction would be that if the seas continue to warm up, we will get less puffins.

But would that mean that perhaps the seas around Iceland or the seas around Lofoten Islands in Norway, which I think is another big puffin population, they might actually be better for fish so the puffins there might do better?

Mike Harris:
Who knows? I mean it’s difficult to know because different puffin populations depend on different fish species. The ones in the North Sea depend on sand eels and to a lesser extent small sprats. When you get up to Lofotens in Norway they are depending on young herring, and you get very far north and to other places they depend on capelin. So it’s a bit complicated the story that we would expect otherwise I suppose. So that’s the first thing. Secondly, this is not the first time that we’ve actually had two bad survival years for puffins, in the early 80s there were two years where puffins survived very badly, and that’s had no effect on the population.

We now think we understand this because puffins, when the chicks go to sea, we thought that they would survive quite badly, but it now appears that they’ve survived very well. And in those days there were obviously a large number of immatures in the population and when a lot of adults died in the ‘80s there were enough immatures waiting that couldn’t get a breeding site and they came in and the population was stable. All the evidence is that survival rates of chicks have declined in recent years, and now we don’t have a surplus waiting to breed.

So we had these two bad years, and there were plenty of spare burrows shall we say for birds, but there were very few immatures available – immature at five years old which were sexually mature but just haven’t got a burrow – to come in and fill the gaps. So I’m now worried that there are very few immatures in this population, and if we get any more reduction in any more over a bad winter for adults we will have another decline in the population.

So my prediction is that if the adult survival is okay the population will be stable; if we get some more bad winters the population will decline further. They won’t become extinct, I’m not preaching doom and despondency, but I think it will go down again. And so the whole crux of this is what is influencing the survival of both immature and adult puffins?

Presenter: Yeah, and there has, well, it seems to me there’s been quite a bit of controversy about that, because thinking back, particular when the crash began to happen, I remember there being a lot of publicity in the Firth of Forth, for example, that Danish boats were coming across and hoovering up large quantities of sand eels from the sea, and the conservationists were saying oh it’s that sand eel fishery that’s doing this. Now the sort of the hip thing is to say oh it’s all about climate change, climate change is the problem these days. I mean, to have you, is that a fashionable bird?

Mike Harris: Fashionable problem. You’re right there was great concern about the sand eel fishery in the Wee Bankie, which is just about 40 kilometres from here and our birds certainly go out that way - that certainly had an effect we think or would have had an effect on the chick’s survival during the breeding season. But puffins outside the breeding season don’t depend on sand eels, because in the winter most sand eels are in the sand, and so puffins then are eating a wide variety of small fish, small crustacea and also marine worms and things.

Presenter: Oh right.

Mike Harris: So any fishery like that is not likely to affect the adult survival; it might affect the chicks, the growth rate of chicks or the chick productivity, but it won’t affect that. That fishery’s now closed, in fact, and has been closed for, well, five, six, seven years now, I suppose, and it’s closed again this year. So that’s not a problem with us, and it’s not going to be the cause of the puffins’ problem.

Right. So which leaves the sea temperature changes as the definite cause or the most likely cause?

Mike Harris:
Well, it’s the probable cause, but it’s difficult to know isn’t it because we don’t know what puffins eat in the winter, so we can’t say what effect climate change will have. I mean common sense suggests it will be but the evidence is not yet there, and we do need to find out more about what puffins eat in the winter. We’ve gone one stage on, we think we know where puffins go, we’ve now got to find out what they’re doing when they’re out there, and what they actually eat.

So technology has made huge progress since you started here in 1973 that probably you wouldn’t have imagined in 1973?

Mike Harris:
No, indeed not.

What next bit of technology would you really like to come along so you could really begin to sort out some of these problems?

Mike Harris: Oh gosh, a wish list. I think what we actually need, and I don’t think we will ever get it, is a device which will tell us on a day-to-day basis accurately where puffins are, like a satellite transmitter, which you can put on a big bird like an eagle or something like that and even ospreys are the classic one.

Which we followed on a programme a couple of years ago, yes?

Mike Harris:
Exactly, I mean these sorts of things but a puffin, you know, it only weighs 400 grams, the devices we put on now weigh between one and two grams, which is fine. But anything more and you would seriously affect the puffin. So I don’t think, I would like to think in my lifetime we will get devices small enough to do that for puffins, but I’ve got my doubts - that’s what I would like.

Puffin on a rock Copyrighted image Icon Copyright: Michael Scott





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