Thanks for invitation to attend this workshop. Michael asked if I would talk about puffins in the UK particularly the studies I ve been involved in

Transcription

1 Thanks for invitation to attend this workshop. Michael asked if I would talk about puffins in the UK particularly the studies I ve been involved in with Mike Harris on the IOM. Pretty big topic going to try and review what we know but also highlight what the knowledge gaps are and think about these in the light of conservation challenges. 1

2 Puffin probably the most popular seabird in the UK. However as its scientific name suggests it is a bird of high latitudes so the UK is very much on the southern edge of the breeding range in the east Atlantic. 2

3 Worth emphasising from the outset that as well as being widespread the puffin is still a very abundant seabird thus although going to be talking about wrecks and threats to puffins, important to keep in mind that while these need to be taken seriously there are an awful lot of puffins in the world ie 20 million! In terms of UK population only a small proportion of the total population. 3

4 Also worth taking a long term view about how puffin abundance and distribution has changed over time. This map shows situation at the end of the nineteenth century indicates that the puffin was abundant and widespread and that the species was commonest in the north and west. 4

5 First proper attempt to census seabirds in Britain and Ireland was in 1968/70. Known as Operation Seafarer. One of the major findings was that numbers of puffins MUCH lower than expected particularly in previous stronghold in the north and west. Great cause for concern. It was therefore decided that an in depth investigation was needed to find out the cause of the decline and whether numbers were still falling. 5

6 Need for detailed studies of puffins to find out more about their breeding and feeding biology. Chose 2 contrasting colonies St Kilda, large colony, west coast where numbers had declined dramatically and small but increasing colony on Isle of May, southeast Scotland in the North Sea. St Kilda spectacular very challenging to work in. Isle of May much less spectacular but logistically much easier. Both sites approach was to use observational methods to collect data on breeding and what birds were feeding on. 6

7 Another major seabird census carried out in provided support for findings from St Kilda and Isle of May and indicated that trend reversed and puffin numbers generally increasing in Britain. Most recent survey of Britain and Ireland in 2000 indicated that the trend continued. Puffins numbers still increasing and some really big colonies in the North Sea in the Firth of Forth and Farne Islands 7

8 However no major survey of British and Irish seabirds since 2000 currently considerable effort going into getting one organised but unlikely to happen before 2016 at the earliest. Puffin is one of the priority species because many of the big colonies haven t been surveyed since 2000 but impression is that numbers may be decreasing. 8

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12 Kittiwake story relationship with temperature isn t a direct one but rather interpretation is that temperature is affecting the prey that kittiwakes take. Simplified view of North Sea pelagic food web has this so called wasp waist structure. Two key mid trophic species the copepd Cal fin and the lesser sandeel Ammodytes marinus. Hear a lot about sandeels but Calanus finmarchicus also important because it is an important food item for sandeels. 12

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14 In fact 2 species of Calanus coldwater Cal finmarchicus and warmer water Cal helgolandicus. Have been major changes in distribution of these two species over the last 50 years in the North Sea. Left hand panels show changes in distribution of Cal fin. Started off very abundant in the North Sea. But over the years abundance decreased and distribution shifted north. Right hand panel shows pattern for the warmer water Cal helgolandicus and its increasing abundance in the North Sea albeit to a lower level than originally shown by Cal fin. Can quantify these changes using a thermal niche model to assess thermal suitability of areas for Cal fin, combine these results with long term data on seabird breeding success to test the hypothesis that success will be positively correlated with suitability. 14

15 Assessed suitability at 4 locations holding important numbers of breeding seabirds. Superimposed these locations on map shown previously indicating SST. Plots show how thermal suitability for Cal fin has changed over time most striking thing is that conditions in East Scotland around the IOM have become much less suitable. Also evidence of declines in recent years around the Faroes and south east Iceland. In contrast thermal conditions around the Norwegian colony in the Lofotens were consistently good. 15

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17 Harder to see puffins in Scotland in 2100! 17

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21 severe storms out in the Atlantic rather than in the North Sea. 21

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24 So far have mainly been considering changes in average climate acting on breeding success. However in general most adult seabirds die when they are away from the colonies and it is also potentially possible that periods of very severe weather can be as important as changes in mean climate variables. UK has recently experienced some severe winter storms and climate models also forecast that such events may occur more frequently in future. So in the next part of the talk I want to focus on how we ve been trying to quantify effects of extreme events on seabird survival. 24

25 One of the things we ve known about for a long time is that sometimes after severe winter storms large numbers of seabirds get washed up on beaches known as seabird wrecks. Rather intriguingly although puffins are one of the commonest birds in the North Sea, prior to 2013 there had never been a major wreck of puffins in the area. However during March 2013 there were prolonged onshore gales and air temperatures were unseasonably low. As the month progressed started to get reports of large numbers of puffins being washed ashore. 25

26 The vast majority of puffins were found between Fraserburgh in the north and Flamborough Head in the south. At least 4,600 dead birds died making it by far the biggest puffin mortality recorded in the North Sea. The wreck occurred as birds were returning to the breeding colonies with the Isle of May and other Forth island colonies and Farne Islands in the centre of the area affected and most of the ringed birds found dead were from these colonies. 26

27 Possible to age puffins over the first few years on the basis of grooves on the bill. Examination of nearly 1000 birds indicated that the vast majority were adults and thus concern was that breeding populations would be affected. 27

28 However the count of occupied puffin burrows on the Isle of May in 2013 was in fact very similar to the counts in 2008 and 2009 and thus NO evidence of a major decline in the breeding population. Count of the puffin colony on the Farnes indicated a similar situation there. 28

29 We could also use colour ringed birds to directly check survival rates of adult birds. Results indicated that survival not exceptionally low over the winter. 29

30 So we seem to have a paradox following exceptionally severe weather unprecedented numbers of puffins found dead in eastern Britain in March Ringing recoveries indicate that local birds involved and aged birds indicate that many birds were of breeding age. However monitoring at local colonies found no evidence that breeding populations had declined or that adult survival was exceptionally low. 30

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32 Setting 2012/13 winter in context. 32

33 Generation of renewable energy reduce CO2 emissions BUT could filling up the seas with these sorts of structures might also have impacts on organisms living there. Area close to the IOM has been identified as somewhere large numbers of wind turbines could be sited. 33

34 Clearly important to know if the proposed wind farm sites are used by puffins. I think 8 and 10 have been discounted. 34

35 Attached miniature GPS loggers to puffins that tracked birds while they were feeding chicks. Plot based on x puffins followed in 20XX. Contours indicate where puffins went on feeding trips. Results indicate that in 20xx puffins did use areas earmarked for wind farms. Need to collect more data to look at patterns in other years and don t know how puffins respond to turbines. Will they act as a barrier so that puffins excluded from the area? Or will puffins continue to use the area but collide with the rotors? 35

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38 Puffins we re familiar with in the UK look very similar to those in Norway. However puffins in the far north of the range in Svalbard much bigger and have much more massive bills. 38

39 Detective work identify when declines occurred. Very difficult to piece together but appeared that declines occurred first in southern colonies and problem shifted north. 39

40 Many reasons for declines suggested and different reasons suggested at different colonies. Thus difficult to identify a common cause. 40

41 Leave numbers and consider biology. 41

42 Moult all wing feathers simultaneously unable to fly. Vulnerable to food shortages, oiling etc. However despite the fact that puffins abundant and many winter in the North Sea still know VERY little about puffin moult even basic things like when exactly it happens. Thus prior to winter of 2012/13 had only looked at a very small sample of dead puffins in the winter. 42

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44 Did the same analysis for the Norwegian colony on Rost except that no data there for guillemots. Here thermal conditions for Cal fin consistently favourable BUT not associated with consistently high seabird breeding success. Indeed in many years complete breeding failures despite the fact that conditions for Cal fin should have been excellent. Clear that in this part of the breeding range temperature related trophic link is currently not the main driver of seabird breeding success. 44

45 Intensive work ended in 1979 Puffins doing much better on IOM than St Kilda higher breeding success, higher quality food but catastrophic decline on St Kilda seemed to be over. Exact cause not clear possibly a whole range of different effects. Another major seabird census carried out in provided support for these findings and indicated that puffin numbers increasing in Britain. 45

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47 To try to resolve the paradox we compared the actual burrow counts (shown in red) with results from a population model (black points). Model used annual data for breeding success and adult survival rate, assumed age of first breeding to be 7 years and that immature survival tracked adult survival. Obtain a very good fit between modelled and observed data. 47

48 Can also use model to estimate the age structure of the IOM population at the time of the wreck. Comparing the age structure of birds in the wreck with the age structure from the model gives remarkably similar percentages. Indicates that the wreck impacted equally across the population no evidence that affected one particular age group. 48

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50 Classic image of puffin a bird with a beakful of fish. How is this achieved? Specially adapted tongue and palate. Although a beakful of fish looks impressive in terms of the value of the load to the chick in practice the opposite is true and the heaviest loads are those made up of one big fish and loads with many small fish are lighter. 50

51 In the intensive period of the puffin work in the 1970s ringed large numbers of puffin chicks with colour rings with different colours for different colonies. Once adult puffins have acquired a burrow and started breeding either use the same burrow year after year or move to a burrow very close by. However immature birds are highly mobile map shows all the colonies where colour-ringed birds from the Isle of May were recorded and the photo shows an immature with a yellow and black ring showing it was born on Craigleith standing next to an adult puffin on the Isle of May. 51

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54 Approx 4600 birds involved in the North Sea wreck and this was the largest number ever recorded dying. However early in 2014 another period of very severe weather with prolonged gales and heavy rain dead seabirds started to be washed up on beaches in southwest England and particularly in France in the Bay of Biscay. Soon apparent that this was an even bigger wreck with the final figure put at nearly 30,000. Again the majority of birds were adult suggesting that the breeding colonies were likely to be affected. 54

55 Although puffin still widespread and numerous definite cause for concern because not only do we think British and Irish population declining but puffin now declining in the main part of the range where the bulk of the population occurs. Thus actual population sizes may be a lot smaller than these figures suggest. 55

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57 Important to know what puffins are feeding on and easier to study than some other seabirds because carry fish back for the chick in the bill. Can catch adults, drop fish which we can collect, count, weigh and identify. Puffins feed on many small fish but on the IOM the 2 main species are sandeels and sprats. 57

58 Have seen changes in the fish species brought in by puffins for their chicks. Proportion of sprat in the diet higher in the 1970s than now. Sandeels the predominant item since the 1980s. 58

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60 Ironically fact that puffins so popular can also potentially pose a threat at some colonies that get a lot of visitors. People want to watch puffins, especially to get photographs of them with the classic beakful of fish however a puffin apparently posing to get its picture taken is actually a puffin unable to feed its chick. 60