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Razorbill (Alca torda)

The following has been adapted from original text by Oscar J. Merne & P. Ian Mitchell in Seabird Populations of Britain and Ireland (with permission from A&C Black, London).

 

The razorbill is a bird of the temperate North Atlantic and adjacent parts of the Arctic Ocean. They breed on both sides of the Atlantic and in the east they breed as far south as Brittany (France), north to Svalbard (Norway) and east to the White Sea in north-west Russia. Razorbills breeding in the British Isles winter along the Atlantic coast of Europe from southwest Norway to Iberia and North Africa, and into the western Mediterranean. Immature birds move significantly further away from their natal colonies than do adults and generally further south, though occasionally they stray west as far as Greenland and the Azores.

Razorbills breed mainly on small ledges or in cracks of rocky cliffs and in associated scree, and on boulder-fields. Rarely, colonies have been found up to 300 m inland. Razorbills are usually associated with colonies of other seabirds, and small numbers scattered among large concentrations of common guillemots and black-legged kittiwakes can easily be overlooked. Razorbill 'nest' sites are usually hidden from view, but the presence of a colony is clearly indicated by the attendance of off-duty birds standing close by. Since it is not usually possible to count occupied sites, the species is difficult to census. Hence, prior to Operation Seafarer (1969-70), very little was known about its numbers and population trends in the UK. Furthermore, interpreting differences between Operation Seafarer (1969-70) and the SCR Census (1985-88) is difficult, since most counts during Operation Seafarer were expressed as pairs, while the SCR Census counted the number of individuals. Despite methodological differences between the two censuses, during 1969–1988, there appeared to be an increase in the total number of razorbills breeding.

Conservation status

Razorbill is currently identified as a conservation priority in the following:

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International importance

UK Population

Biogeographic Population

% World Population

187,100 Individuals

23.6 (ssp. islandica)

20.2

The UK population figure (rounded to the nearest hundred) was derived from data in Mitchell, P.I., Newton, S.F., Ratcliffe, N. and Dunn, T.E. (eds.) 2004. Seabird Populations of Britain and Ireland. Poyser, London. This was also the source of figures for the Biogeographic and World populations.

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UK population estimates and change 1969–2002 (census data)

The count unit for razorbills is individuals (on suitable breeding ledges), which may include off-duty adults, non-breeders and immature birds, as well as – where nests are visible – brooding and incubating birds. At a few sites it is possible to count apparently occupied sites or nests (AOS or AON). However, in order to compare counts between years, all counts of AOS and AON were divided by 0.67 to estimate the equivalent count of individuals. In Seabird 2000, only 3% of the population estimate (in terms of birds) was converted from counts of AOS and AON, comparable to the SCR Census when converted counts comprised 5% of the total estimate. In contrast, 78% of the total population estimate of razorbills in Operation Seafarer was expressed as pairs (i.e. AOS or AON). However, it is unclear how surveyors determined 'pairs' present in each colony. Therefore, comparisons of Operation Seafarer data with subsequent counts of individuals should be treated with caution.

During Seabird 2000 and the SCR Census survey, methods prescribed counting razorbills between 1 and 21 June, to coincide with the late incubation and main nestling period, and during 08:00 to 16:00 hrs (BST) to coincide with the periods of most consistent attendance by birds at the colony. This may not necessarily coincide with the maximum numbers of birds attending the cliffs during a season, but instead provides the most comparable measure of attendance when using one-off counts. In Seabird 2000, 43% of counts were conducted during this period and time, with a further 21% in the prescribed period, but either outwith the correct time or the time was not noted. During the SCR Census, only 37% of counts were conducted on the correct dates but actual time was never recorded. These count windows were not prescribed during Operation Seafarer and so some counts were carried out later in July or even in early August when many successful adults would have left with their chicks and when failed breeders would have deserted, resulting in an underestimate.

 

Operation Seafarer    

(1969-70)

Seabird Colony Register    

(1985-88)

Seabird 2000    

(1998–2002)

UK Population estimate (Individuals)

132,734

154,219

187,052

% change since previous census

n/a

+16

+21

For census results for individual countries and Ireland, the Channel Islands and the Isle of Man see under relevant sections below.

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Distribution/abundance

The Seabird 2000 census provides the most comprehensive recent assessment of the distribution and abundance of breeding seabirds. Numbers of razorbill found in different regions, and a map showing the locations and size of colonies, is provided in the Seabird 2000 razorbill results page.

The locations sampled during the annual Seabird Monitoring Programme provide some information on distribution and are accessible via the Seabird Monitoring Programme online database.

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Annual abundance and productivity by geographical area

With reference to the regional accounts below please note the following:

Breeding abundance: graphs of abundance index with 95% confidence limits are only shown for a region where the trend produced has been deemed accurate (see methods of analysis). Where a trend was thought to be inaccurate, graphs of abundance at major colonies in a region may be shown instead, particularly if such colonies hold greater than 10% of the regional population, are monitored frequently and may thus help illustrate regional population fluctuations outwith national censuses. Occasionally, too few data have been collected regionally to produce either of these.

Productivity: graphs of productivity are only shown if analysis of breeding success data produced a significant result for regional and/or year effects (again see methods of analysis). If results were not significant, then a regional mean productivity value is given. However, on some occasions, too few data are available from which to provide a meaningful average. Furthermore, for 11 species where the quality of monitoring data available was considered high, population viability analysis was undertaken at the UK level and the results of this are also reported.

 

United Kingdom

Breeding abundance

razorbill-uk-ab.jpg

Figure 1. Trend in UK abundance index (solid line) of razorbill 1986–2018 with 95% confidence limits (dotted lines; drawing of upper limit restricted to preserve detail in the abundance index). Based on SMP data; view the methods of analysis.

 

Over the longer term, census results show that the UK razorbill population increased by 16% between 1969-70 and 1985-88. Since then, like the guillemot, the UK population index for razorbill has increased compared to the 1986 baseline. After a period of stability between 1986 and 1991, the SMP sample index increased fairly steadily until 2003, peaking at 78% above the 1986 value. The reasons for the increase are unknown. Between 2005 and 2010, the index declined, possibly as a result of so-called 'density-dependent' effects, where growth at the densest colonies slowed or reversed when competition for space and food reached critically high levels. However, in autumn 2007, a ‘wreck’ of adult razorbills in the Skagerrak (the strait between Denmark, Norway and Sweden) and North Sea, most of which originated from Scottish colonies (see Scotland section), may also have contributed to the declining trend. The index has risen since 2010, with 2017 having the highest index value since the baseline began in 1986, although wide confidence intervals suggest this apparent increase should be treated with caution.

Table 1 below shows how numbers have changed at some of the most important UK colonies (those in the SPA network) in the period since they were surveyed for Seabird 2000. The largest declines recorded since Seabird 2000 have been in colonies in northern and western Scotland, while the largest colonies in England and Wales have all increased.

Table 1. Recent counts of the number of razorbill (IND) recorded in SPAs in Britain and Ireland compared to the number recorded during Seabird 2000. The percentage that each colony has changed between counts, and the per annum change, is also provided. (Note: data for St Abb's Head relate to only part of the SPA).

 

Area

SPA Name

Seabird 2000 (Year)

Count (Year)

Change (%)

per annum

Shetland

Foula

4,200 2000

559 2007

-87

-25.0

Shetland

Fair Isle

3,599 2000

1,930 2015

-46

-4.1

Orkney

West Westray Cliffs

2,412 1999

982 2017

-59

-4.9

East Coast

Troup, Pennan and Lion's Heads

4,831 2001

4,422 2017

-8

-0.6

East Coast

Fowlsheugh

6,362 1999

14,063 2018

+121

+4.3

East Coast

Forth Islands

4,830 2001

5,466 2018

+13

+0.7

East Coast

St Abb's Head NNR

2,214 1998

2,683 2018

+21

+1.0

East Coast

Flamborough Head and Bempton Cliffs

8,539 2000

27,967 2017

+228

+7.2

The Minch

Handa

16,991 2001

5,047 2014

-70

-8.9

The Minch

Shiant Isles

8,046 1999

8,029 2015

0

0

The Minch

Mingulay and Berneray

22,900 1998

17,400 2014

-24

-1.7

Irish Sea

Rathlin Island

20,860 1999

22,975 2011

+10

+0.8

Irish Sea

Skomer and Skokholm

5,306 2000

10,120 2018

+91

+3.7

Irish Sea

Lambay Island

4,337 1999

7,353 2017

+70

+3.0

 

Productivity

razorbill-uk-prod.jpg

Figure 2. Trend in UK productivity (no. of chicks fledged per pair) of razorbill, 1986–2018. Based on SMP data; view the methods of analysis.

 

Razorbill productivity was fairly stable from 1986 to 1993 but then declined to a low point in 2008 of 0.38 chicks fledged per pair. Between 2010 and 2017, however, there has been a steep upward trend from 0.38 to 0.65 chicks fledged per pair. In 2018, the trend declined slightly to 0.63 razorbill chicks being fledged per pair.

Success at several monitored colonies in Scotland and Wales has been particularly poor in recent years compared to that recorded in England. The decline in productivity coincides with food shortages, especially notable at colonies in the north and east of the UK and, at the Isle of May, a decrease in the energy content of fish brought to chicks1. The association of years of low razorbill productivity with rising sea surface temperatures (SST) due to climate change is uncertain, though there are indications that a decline in sandeel stocks may be linked to warming sea temperatures2.

Analysis of the SMP dataset found mean productivity of razorbill between 1986 and 2008 to be 0.55 and that it was declining at a rate of 0.01 chicks per nest per year3. This equates to a decline in productivity of 26% over the study period. The quality of the dataset meant a change in productivity greater than 25% would be detected with confidence. However, the data do not have sufficient power to detect a change in productivity of 10% or less. Population viability analysis (using available life history information on population size, clutch size, age at first breeding and survival rates of different age classes) predicted that were this rate of productivity to be sustained, razorbill abundance would decline by only 4% over 25 years. Were productivity to drop below 0.50, populations would decline by 25% over 25 years. Success would have to half again for a 50% decline over 25 years to be observed.

 

Scotland

Population estimates and change 1969–2002 (census data)

 

Operation Seafarer    

(1969-70)

Seabird Colony Register    

(1985-88)

Seabird 2000    

(1998–2002)

Population estimate (Individuals)

111,038

123,586

139,186

% change since previous census

n/a

+11

+13

 

Breeding abundance

Razorbill Scotland breeding abundance.jpg

Figure 3. Trend in abundance index (solid line) of razorbill in Scotland, 1986–2018 with 95% confidence limits (dotted lines; drawing of upper limit restricted to preserve detail in the abundance index). Based on SMP data; view the methods of analysis.

 

In Scotland, census data indicate the number of razorbills increased between Operation Seafarer and Seabird 2000. Numbers during the Seabird Colony Register were 11% higher than in 1969-70 and had increased again, by 13%, during Seabird 2000. The abundance trend extrapolated from colonies sampled for the SMP shows an increasing trend until 2001 but declined until the 2009 to 2013 period, when the index lay close to the 1986 baseline. Since then, the index has increased and in 2018 was 82% above the baseline. In autumn 2007, a ‘wreck’ of adult razorbills in the Skagerrak and North Sea, most of which originated from Scottish colonies, may have contributed to the dip in the trend between 2007 and 20094. Whole-colony counts submitted to the SMP from 52 sites indicate that these sites held 28,493 razorbill individuals in 2018, an increase of 28% compared to the total from the same sites counted during Seabird 2000.

 

Productivity

razorbill-scotland-prod.jpg

Figure 4. Trend in productivity (no. of chicks fledged per pair) of razorbill at Scottish colonies, 1986–2018. Based on SMP data; view the methods of analysis.

 

The trend in Figure 4 closely matches that for the UK. Data collected at colonies in Scotland indicate declining productivity since the early 1990s, although the decline has not been constant. Some colonies recorded consistently low levels of productivity between 2009 and 2018. At these colonies, in the years when chicks fledged, success was only been above 0.25 on Papa Westray five times (mainly from 2014 onwards); and on Fair Isle has only been above 0.50 five times (again from 2014 onwards but not during 2017). The few data available from Sumburgh Head suggest low productivity has been widespread in the Northern Isles in recent years5. Mingulay (Western Isles), where productivity monitoring began in 2013, had poor breeding seasons in 2013 (0.23), 2014 (0.28) and 2015 (0.30). In contrast, the frequently monitored colonies at North Sutor and on the Isle of May (both east coast of Scotland) were relatively successful between 2009 and 2018, fledging an average of 0.51 and 0.56 chicks per site respectively, with neither colony recording complete failure.

 

England

Population estimates and change 1969–2002 (census data)

 

Operation Seafarer    

(1969-70)

Seabird Colony Register    

(1985-88)

Seabird 2000    

(1998–2002)

Population estimate (Individuals)

5,405

10,101

11,144

% change since previous census   

n/a

+87

+10

 

Breeding abundance

razorbill-england-ab.jpg

Figure 5. Abundance of razorbill at Flamborough Head and Bempton Cliffs, 1986–2017.

 

Razorbill numbers in England almost doubled between Operation Seafarer and the Seabird Colony Register to 10,101 individuals. By the time of Seabird 2000, a further increase of 10% had occurred. Few colonies of any great size are monitored regularly from which to draw firm conclusions about trends since Seabird 2000. However, available data suggest an increase may have occurred. For example, in 2017 and 2018, 24 monitored colonies held 33,000 individuals compared to 10,000 during Seabird 2000. Data from the largest English colony, at Flamborough Head and Bempton Cliffs (Figure 5), found a substantial increase with 27,967 individuals being recorded in 2017, an increase of 231% since the Seabird 2000 census (8,463 individuals), and double the total English population recorded during that census.

 

Productivity

Productivity data have been collected in England since 1996, initially from the Farne Islands and then at Bempton Cliffs since 2009. Analysis showed no statistically significant variation over time. On average, razorbills fledged 0.64 chicks per site per year.

 

Wales

Population estimates and change 1969–2002 (census data)

 

Operation Seafarer    

(1969-70)

Seabird Colony Register    

(1985-88)

Seabird 2000    

(1998–2002)

Population estimate (Individuals)

9,316

9,501

12,638

% change since previous census

n/a

+2

+33

 

Breeding abundance

razorbill-wales-ab.jpg

Figure 6. Trend in abundance index (solid line) of razorbill in Wales, 1986–2018 with 95% confidence limits (dotted lines; drawing of upper limit restricted to preserve detail in the abundance index). Based on SMP data; view the methods of analysis.

 

The trend in abundance for razorbills at Welsh colonies has generally been upward since 1986, with a new peak reached in 2016 (180% above baseline). National census data show numbers were stable between Operation Seafarer and the Seabird Colony Register but had increased by 33% by Seabird 2000 – a trend which has continued to the present. Almost 75% of Welsh razorbill colonies were surveyed in 2018 (51), with numbers totalling 15,992 individuals, 26% more than were recorded in the whole country during Seabird 2000.

 

Productivity

razorbill-wales-prod.jpg

Figure 7. Trend in productivity (no. of chicks fledged per pair) of razorbill in Wales, 1986–2018. Based on SMP data; view the methods of analysis.

 

Razorbill productivity data were not collected at Welsh colonies prior to 1993. Although productivity has varied between years, there was a sharp decline until 2012 after which it rose to 2013 and then declined again before rising to 0.63 chicks fledged per pair in 2018. In recent years (2003 onwards) almost all data have been collected on Skomer (note: no data were collected in 2011) where productivity in 2018 (0.62) rose above 0.56 for the first time since 2009. With productivity decreasing between 1998 and 2008 and low rates of survival also recorded at Skomer in recent years (see Figure 10 below), it is of no surprise that abundance also began to fall from 2016 onwards (Skomer holds about 30% of the Welsh razorbill population).

 

Northern Ireland

Population estimates and change 1969–2002 (census data)

 

Operation Seafarer    

(1969-70)

Seabird Colony Register    

(1985-88)

Seabird 2000    

(1998–2002)

Population estimate (Individuals)

6,975

11,031

24,084

% change since previous census

n/a

+58

+118

 

Breeding abundance

Razorbill numbers in Northern Ireland have been on the increase since Operation Seafarer according to national census data. The Seabird Colony Register recorded 58% more individuals than during the first census, which was followed by a further large increase by Seabird 2000.

Only eight or nine colonies exist and few of these are monitored frequently. Most of the national population (87% during Seabird 2000) is found on Rathlin Island where a count in 2007 recorded 10,684 individuals – a severe decline of 49% since Seabird 2000. A repeat survey in 2011 recorded 22,975 individuals – more than double that in 2007 – making it the second largest colony in the UK. Obviously, given the increase that occurred afterward, the numbers of razorbills on Rathlin Island in 2007 must have been unusually low. However, there is a lack of detail from Rathlin Island and other colonies in the vicinity from which to form any conclusions as to why such an increase occurred. However, it should be noted that numbers of razorbills in attendance at the colony can be subject to large fluctuations, particularly as many birds may not breed each year. Only two small colonies have been surveyed recently; The Gobbins and Muck held 1,722 individuals in 2013 compared to 901 individuals during Seabird 2000. However, in 2014, numbers at these colonies were very low totalling a mere 642 individuals. In 2015, numbers increased to 1,177 individuals which may mean the sudden drop observed in 2014 was due to many birds failing to breed. In 2018, 1,618 individuals were recorded at both colonies. Numbers at the other colonies have not been assessed since 2000 when they held a total of 1,926 individuals. However, without a whole-colony count of Rathlin Island, it is not possible to draw any meaningful assumptions on the current status of the razorbill population in Northern Ireland.

 

Productivity

Data submitted to the SMP on the productivity of razorbills in Northern Ireland are sparse; thus, no meaningful average productivity value can be given.

 

Republic of Ireland

Population estimates and change 1969–2018 (census data)

 

Operation Seafarer    

(1969-70)

Seabird Colony Register    

(1985-88)

Seabird 2000    

(1998–2002)

Republic of Ireland Census

(2015-18)

Population estimate (Individuals)

33,989

20,987

27,446

33,689

% change since previous census   

n/a

-38

+31

+23

 

Breeding abundance

In contrast to Northern Ireland, razorbill numbers in the Republic of Ireland were found to have declined by 38% between Operation Seafarer and the Seabird Colony Register. Although a subsequent increase had occurred by Seabird 2000, the population was still slightly below that recorded during the first census, again in contrast to changes in Northern Ireland where razorbill numbers doubled over the same period. A recent seabird census in the Republic of Ireland counted 33,689, an increase of 23% compared to Seabird 20006. Although the national trend was positive, there was much variation in numbers since the Seabird 2000 census. Most notable of these was the change in breeding population estimates at the Cliffs of Moher which had decreased by 48% (from 7,700 to 4,046 individuals). In contrast, Great Saltee and Lambay Island experiencing substantial increases of at least 70% from 3,239 and 4,337 individuals respectively. Horn Head recorded 6,812 individuals, remaining largely stable. The abundance of razorbills at colonies can be closely associated with prey abundance e.g. sprat, therefore, it is possible that local changes in food availability are driving the apparent regional differences in population trends7.

 

Productivity

Data submitted to the SMP on the productivity of razorbills in the Republic of Ireland are sparse; thus, no meaningful average productivity value can be given.

 

All Ireland

Population estimates and change 1969–2002 (census data)

 

Operation Seafarer    

(1969-70)

Seabird Colony Register    

(1985-88)

Seabird 2000    

(1998–2002)

Population estimate (Individuals)

40,964

32,018

51,530

% change since previous census

n/a

-28

+61

 

Breeding abundance

The razorbill population for the whole of Ireland was 51,530 individuals during Seabird 2000, 61% higher than during the Seabird Colony Register when numbers were found to have declined by 28% since Operation Seafarer. Most of the Northern Irish population (87% during Seabird 2000) is found on Rathlin Island where a count in 2011 recorded 22,975 individuals – making it the second largest colony in the UK and the largest in Ireland. A recent seabird census in the Republic of Ireland recorded 33,689, an increase of 23% compared to Seabird 20006. Without a more recent whole-colony count from Rathlin Island, it is not possible to draw any meaningful assumptions on the current status of the razorbill population in the whole of Ireland.

 

Productivity

Data submitted to the SMP on the productivity of razorbills throughout Ireland are sparse; thus, no meaningful average productivity value can be given.

 

Isle of Man

Population estimates and change 1969–2018 (census data)

 

Operation Seafarer

(1969-70)

Seabird Colony Register

(1985-88)

Seabird 2000

(1998–2002)

Isle of Man Census

(2017-18)

Population estimate (Individuals)

897

848

1,524

682

% change since previous census

n/a

-5

+80

-55

 

Breeding abundance

razorbill-iom-ba.jpg

Figure 8. Abundance of razorbill on the Calf of Man, 1986–2017.

 

Between Operation Seafarer and the Seabird Colony Register the number of razorbills on the Isle of Man was relatively stable. By Seabird 2000, the population had increased by 80% to 1,524 birds. A seabird census was carried on the Isle of Man in 2017, recording a total of 682 individual razorbills, a 54% decrease since Seabird 20008. On the Calf of Man, which held between 20–25% of the razorbill population during the SCR and Seabird 2000 censuses, numbers have shown considerable variation over time (Figure 8). However, differences in the method used to collect data makes it difficult to draw any conclusion to the trend. For instance, in 2010 (331 individuals) were close to the peak count recorded in 1999 (362 individuals). However, counts in 1999 were from land only while those in 2010 were from land and sea. In 2013, 226 individuals were recorded but counts were done from sea only.

 

Productivity

Data submitted to the SMP on the productivity of razorbills on the Isle of Man are sparse; thus, no meaningful average productivity value can be given.

 

Channel Islands

Population estimates and change 1969–2015 (census data)

 

Operation Seafarer

(1969-70)

Seabird Colony Register

(1985-88)

Seabird 2000

(1998–2002)

Channel Islands Census

(2015)

Population estimate (Individuals)

63

81

65

112

% change since previous census

n/a

+29

-20

+72

 

Breeding abundance

The small population of razorbills nesting on the Channel Islands numbered just 65 individuals during Seabird 2000, almost the same as that recorded by Operation Seafarer. Razorbills were slightly more numerous during the Seabird Colony Register, when 81 individuals were recorded. In 2015 a seabird census of the Channel Islands recorded 112 razorbills, an increase of 72% since Seabird 20009.

 

Productivity

No systematic data on the productivity of razorbills on the Channel Islands have been submitted to the SMP.

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UK phenology, diet, survival rates

Phenology

No systematic data on phenology (timing of life-cycle events) have been collected as part of the SMP.

 

Diet

No systematic data on razorbill diet have been collected as part of the SMP.

 

Return rate and survival rates

Important notes on interpretation: Estimation of razorbill adult return and survival rates are currently undertaken at two sites within the Seabird Monitoring Programme – the Isle of May (North-east Fife) and Skomer (Dyfed). Return rates are based on sightings of individually colour-ringed birds and are calculated as the proportion of marked birds present in year one that is seen in the following year. Because not every adult alive is seen each year, return rates for 2018 presented here for Isle of May need to be treated as minimum estimates of survival of birds seen in 2017. In contrast, survival estimates do take into account birds that are not seen one year but which re-appear in following years.

razorbill-annual-return-rate.jpg

Figure 9. Annual return rate of razorbills breeding on the Isle of May, 1987–2018.

 

The annual return rate of razorbills from the Isle of May (Figure 9) shows fluctuation over time with a recent increase. Return rates between 2009 and 2012 and in 2017 were among the highest recorded there. After a steep decline in 2008, return rate increased up to 2018 when it was equivalent to 1986 (92.1) when monitoring began. In contrast the survival rate from Skomer (Figure 10) doesn’t show any clear trend over the period monitored, though fluctuation has become more pronounced in recent years with much lower rates in recorded in 2007 and 201410. On Skomer, recent years show survival rates returning to the high levels recorded at the beginning of this long-term study. Survival across the Skomer study (1970–2017) averages 0.90, and in 2016-17 was 0.8511.

There appears to be no relationship between the UK population trend (nor the trends in Scotland and Wales) and survival/return rates at the two colonies where this is measured. The low return rate at the Isle of May in 2008 followed a post-breeding 'wreck' of adult birds in the Skagerrak (the strait between Norway, Denmark and Sweden) during autumn 2007. Ringing recoveries indicated birds had mainly originated from northern or eastern Scotland4. A further 'wreck' off the east coasts of Scotland and northern England during winter 2012/13, when many adult and juvenile guillemots and razorbills died, may have been the cause of low return rates on the Isle of May during the 2013 breeding season.

In addition, the winter of 2013/14 saw a succession of severe storms from late January to the beginning of March result in a large 'wreck' of seabirds along Atlantic coasts from England and Ireland to Spain. A minimum of 54,000 seabirds, mostly auks, were washed ashore dead or dying. Examination of many corpses revealed birds were emaciated with empty stomachs indicating starvation as the main cause of death although a small proportion showed signs of oil contamination12. Overall, about 10% of the casualties were razorbills12. However, in Cumbria, 70% of 850 seabirds washed ashore dead or dying during this 'wreck' were razorbills13. Biometric data from 43 corpses recovered from Cumbrian beaches indicated birds were of the subspecies islandica which breeds in Britain and Ireland, France and Iceland. Rings recovered from razorbill corpses (from beaches in England and in France) also indicated birds originated from colonies around the UK and Ireland13. The majority of birds examined were found to be adults. The total mortality will be much higher than reported because not all beaches were checked, birds were washed ashore over a number of weeks and many birds will be lost unrecorded at sea12.

On Skomer, after collecting sufficient data to observe the effect of this event on long-term population parameters (scientists require two years’ data following a winter to be confident of survival estimates), a considerable drop in the survival of adult breeding razorbills is clear (Figure 10), after a period of steady increase over the last 30 years. The survival of breeding adult razorbills after the seabird wreck in the winter of 2013-14 was just 0.59, more than 30% below the study average of 0.90 (1970–2014)14.

 

razorbill-survival-rate.jpg

Figure 10. Annual survival rate of razorbills breeding on Skomer, 1986–2018.

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References

1 Wanless, S., Harris, M.P., Redman, P. and Speakman, J.R. 2005. Low energy values of fish as a probable cause of a major seabird breeding failure in the North Sea. Marine Ecology Progress Series, 294, 1–8.

2 Heath, M., Edwards, M., Furness, R., Pinnegar, J. and Wanless, S. 2009. A view from above: changing seas, seabirds and food sources in Marine Climate Change Ecosystem Linkages Report Card 2009. eds. Baxter, J.M., Buckley, P.J. and Frost, M.T. Online science reviews, 24pp. www.mccip.org.uk/elr/view

3 Cook, A.S.C.P. and Robinson, R.A. 2010. How representative is the current monitoring of breeding success in the UK? BTO Research Report, No. 573, British Trust for Ornithology, Thetford.

4 Heubeck, M., Aarvak, T., Isaksen, K., Johnsen, A., Petersen, I.K. and Anker-Nilssen, T. 2011. Mass mortality of adult Razorbills Alca torda in the Skagerrak and North Sea area, autumn 2007. Seabird, 24, 11–32.

5 Miles, W. and Mellor, M. 2018. SOTEAG Ornithological Monitoring Programme 2018 Report. The Scottish Oceans Institute, School of Biology, University of St Andrews.

6 Cummins, S., Lauder, C., Lauder, A. and Tierney, T. D. 2019. The Status of Ireland’s Breeding Seabirds: Birds Directive Article 12 Reporting 2013 – 2018. Irish Wildlife Manuals, No. 114. National Parks and Wildlife Service, Department of Culture, Heritage and the Gaeltacht, Ireland.

7 Hjernquist, B. and Hjernquist, M. 2010. The effects of quantity and quality of prey on population fluctuations in three seabird species. Bird Study, 57, 19–25.

8 Hill, R.W., Morris, N. G., Bowman, and K. A., Wright, D. 2019. The Isle of Man Seabird Census: Report on the census of breeding seabirds in the Isle of Man 2017-18. Manx BirdLife. Laxey, Isle of Man.

9 Veron, M. and Veron, C. 2016. Seabird Count 2015; monitoring the status of Guernsey’s Seabirds. La Société Transactions, Channel Islands.

10 Newell, M, Harris, M.P., Burthe, S., Bennett, S., Gunn, C.M., Wanless S. and Daunt, F. 2019. Isle of May seabird studies in 2018. Unpublished JNCC Report, Joint Nature Conservation Committee, Peterborough.

11 Stubbings, E.M., Büche, B.I., Riordan, J.A., Baker, B. and Wood, M.J. 2018. Seabird monitoring on Skomer Island in 2018. Unpublished JNCC Report, Joint Nature Conservation Committee, Peterborough.

12 Jessop, H. Seabird tragedy in the north-east Atlantic winter 2013/14. Unpublished RSPB report, Royal Society for the Protection of Birds, Sandy.

13 Sellers, R.S. 2014. Mass mortality of razorbills and other seabirds on the coast of Cumbria in February 2014. Lakeland Naturalist, 2, 63–71.

14 Stubbings, E.M., Büche, B.I., Miquel Riera, E., Green, R.M. and Wood, M.J. 2015. Seabird monitoring on Skomer Island in 2015. Unpublished JNCC Report, Joint Nature Conservation Committee, Peterborough.

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Partners

Data have been provided to the SMP by the generous contributions of its partners, other organisations and volunteers throughout Britain and Ireland. Partners to the SMP are: BirdWatch Ireland; The British Trust for Ornithology; UK Centre for Ecology and Hydrology; Natural Resources Wales; Department of Environment, Food and Agriculture (Isle of Man); Department of Environment, Heritage and Local Government (Republic of Ireland); States of Guernsey Government; JNCC; Manx Birdlife; Manx National Heritage; The National Trust; National Trust for Scotland; Natural England; Northern Ireland Department of Agriculture, Environment and Rural Affairs; The Royal Society for the Protection of Birds; Scottish Natural Heritage; Seabird Group; Shetland Oil Terminal Environmental Advisory Group; Scottish Wildlife Trust. More about the SMP partners >>

 

Image of Razorbill appears courtesy of Ian Rendall ©, is subject to international copyright law and may not be reproduced in any form whatsoever.

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SMP Report 1986–2018

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