Razorbill Alca torda

Status;  International importance;  Population estimates;  Distribution;  Annual abundance/ productivity; Phenology/diet/survival

 

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Description

Razorbill vignette

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 300m 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:

EC Birds Directive - migratory species

Amber listed in Birds of Conservation Concern 4  (2015 update)

(further information on Conservation Designations for UK Taxa)

Amber listed in Birds of Conservation Concern in Ireland 2014-2019 (2014 update)

 


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 andIreland. Poyser, London. This was also the source of figures for the Biogeographic and World populations.

 


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.

 


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 (PDF, 2.0 mb).

 

An interactive map is available on the NBN Gateway, where you can filter to display only the Seabird 2000 data. For more recent, but less comprehensive, coverage view the distribution on the NBN with all available contributing datasets.

 

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

 

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.  

 



 

Breeding abundance

 

UK razorbill abundance trend

Figure 1: Trend in UK abundance index (solid line) of razorbill 1986-2015 with 95% confidence limits (dotted lines). Based on SMP data; view the methods of analysis (PDF 158 kb).

 

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 2015 having the highest index value since the baseline began in 1986, although wide confidence intervals suggest this apparent increase should be treated with caution. While predictions of future population trends are uncertain, the observed low productivity in recent years may lead to future declines.

 

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 important colonies in England, Wales and Northern Ireland have all increased.

 

Area SPA Name Seabird 2000 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 813 2007 -66 -12.7
East Coast Troup, Pennan and Lion's Heads 4,831 2001 3,001 2007 -38 -7.6
East Coast Fowlsheugh 6,362 1999 7,426 2015 +17 +1.0
East Coast Firth of Forth Islands 4,830 2001 5,038 2015 +4 +0.3
East Coast St Abb's Head NNR 2,214 1998 1,820 2013 -18 -1.3
East Coast Flamborough Head and Bempton Cliffs 8,539 2000 14,927 2008 +75 +7.2
West Coast Handa 16,991 2001 5,047 2014 -70 -8.9
West Coast Shiant Isles 8,046 1999 6,340 2008 -21 -2.6
West Coast Mingulay and Berneray 22,900 1998 17,400 2014 -24 -1.7
West Coast Rathlin Island 20,860 1999 22,975 2011 +10 +0.8
West Coast Skomer and Skokholm 5,306 2000 9,871 2015 +86 +4.2

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

 

Productivity

 

UK razorbill productivity trend

Figure 2: Trend in UK productivity (no. of chicks fledged per pair) of razorbill, 1986-2015. Based on SMP data; view the methods of analysis (PDF 158 kb).

 

Razorbill productivity was fairly stable from 1986 to 1993 but declined thereafter - with several unproductive breeding seasons during the last decade - since 2008 however, there has been an upward trend.

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 the productivity of sandeel stocks may be linked to warming sea temperatures2.

 

Analysis of the SMP dataset found the mean breeding success of razorbill between 1986 and 2008 was 0.55 and declined at a rate of 0.01 chicks per nest per year3. This equates to a decline in success of 26% over the study period. The quality of the dataset meant a change in breeding success greater than 25% would be detected with confidence. However, the data do not have sufficient power to detect a change in breeding success 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 breeding success to be sustained, razorbill abundance would decline by only 4% over 25 years. Were breeding success 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.

 

 

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

 

Scotland razorbill abundance trend

Figure 1: Trend in abundance index (solid line) of razorbill in Scotland, 1986-2015 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 (PDF 158 kb).

 

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 2004, but declines thereafter so that in 2014 the abundance index is close to the 1986 baseline. In 2015, the index is based 39% 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 already declining trend4.

 

Productivity

 

Scotland razorbill productivity trend

Figure 2: Trend in productivity (no. of chicks fledged per pair) of razorbill at Scottish colonies, 1986-2015. Based on SMP data; view the methods of analysis (PDF 158 kb).

 

The trend in Figure 2 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 have consistently recorded low levels of success during the last ten years. For example, on both Fair Isle (Shetland) and on Papa Westray (Orkney), complete or near complete breeding failure has occurred in five of the last ten years. In addition, in the years when chicks have fledged during the last decade, success has only been above 0.25 on Papa Westray twice, in 2014 (0.25) and 2015 (0.33); and on Fair Isle has only been above 0.50 twice, in 2014 (0.68) and in 2015 (0.71). The few data available from Sumburgh Head (Shetland; an average of 0.37 chicks fledged per site between 2011 and 2015) and Marwick Head (Orkney, 0.63; over the same period) suggest low breeding success has been widespread in the Northern Isles in recent years. Data from Mingulay (Western Isles), where breeding success was monitored for the first time in 2013, also indicated poor breeding seasons in 2013 (0.23), 2014 (0.28) and 2015 (0.30). In contrast, frequently monitored colonies at North Sutor (Ross and Cromarty) and on the Isle of May (North-east Fife) have been relatively successful over the last decade, fledging an average of 0.65 and 0.59 chicks per site, respectively, with neither colony recording complete failure. 

 

 

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 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 2015, 31 monitored colonies (including all Isles of Scilly) held 2,621 individuals compared to 635 individuals during Seabird 2000. These numbers do not take into consideration the individuals counted in 2014 from five additional colonies which totalled 947. Older data, from the largest English colony at Flamborough Head and Bempton Cliffs SPA (Humberside), also found a substantial increase. Monitoring in 2008 recorded 14,927 individuals, an increase of 138% since the Seabird 2000 census (6,282 individuals counted in 2000), and indeed several thousand higher than the total national population from that census. The reasons behind such a large increase at this colony are unknown but could be due to differences in count methodology; it is unlikely such increases have come about due to increased productivity or immigration.

 

Productivity

 

Productivity data have been collected in England since 1996, only at the Farne Islands (Northumberland) initially, with data collected at Bempton Cliffs since 2009. Analysis showed no statistically significant variation over time. On average, razorbills fledged 0.68 chicks per site per year

 

 

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

 

Wales razorbill abundance trend

Figure 1: Trend in abundance index (solid line) of razorbill in Wales, 1986-2015 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 (PDF 158 kb).

 

The trend in abundance for razorbills at Welsh colonies has generally been upward since 1986, with a new peak reached in 2015. National census data show numbers were stable between Operation Seafarer and the Seabird Colony Register, but then increased by 33% by Seabird 2000 - a trend which has continued to the present. Although only about one-quarter of Welsh razorbill colonies were surveyed in 2015 (28), numbers totalled 20,831 individuals, 64% more than was recorded in the whole country during Seabird 2000.  

 

Productivity

 

Wales razorbill productivity trend

Figure 2: Trend in productivity (no. of chicks fledged per pair) of razorbill in Wales, 1986-2015. Based on SMP data; view the methods of analysis (PDF 158 kb).

 

Razorbill productivity data were not collected at Welsh colonies prior to 1993. Although productivity has varied between years there is a sharply declining trend which appears to have steepened over the last decade. In recent years (2003 onwards) almost all data have been collected on Skomer (Dyfed) (note: no data were collected in 2011) where productivity has not risen above 0.59 since 2010. With productivity falling and low rates of survival also recorded at Skomer in recent years (see Figure 4 below), it would be of no surprise if abundance also began to fall (Skomer holds about 30% of the Welsh razorbill population). However, this does not appear to be happening at present.  

 

 

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 large increase at Seabird 2000; numbers more than doubled to over 24,000 individuals. Only eight or nine colonies exist but few of these are monitored frequently. Most of the national population (87% during Seabird 2000) is found on Rathlin Island (Co. Antrim) 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 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 of the island from which to form any conclusions as to why such an increase occurred. Only two small colonies have been surveyed recently; The Gobbins and Muck (both Co. Antrim) 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. This sudden drop over the course of one year perhaps suggests that many razorbills did not breed in 2014. Numbers at the other colonies have not been assessed since 2000 when they held a total of 1,926 individuals. However, assuming that counts in 2014 were atypical, overall recent figures suggest the Northern Ireland razorbill population has increased.

 

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.

 

 

Population estimates and change 1969-2002 (census data)

 

 

Operation Seafarer    

(1969-70)

Seabird Colony Register    

(1985-88)

Seabird 2000    

(1998-2002)

Population estimate (Individuals) 33,989 20,987 27,446
% change since previous census    N/a -38 +31

 

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. Colonies monitored since Seabird 2000 were few, however razorbills were counted at 25 colonies in 20154. At these a total of 31,115AON were recorded compared to 27,749 individuals during Seabird 2000, an increase of 16%. The majority of individuals (24%) were recorded on Lambay Island (Co. Dublin) and (22%) at Horn Head (Co. Donegal). 

 

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.

 

 

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. Few colonies are monitored frequently in either Northern Ireland or the Republic of Ireland, so any information as to the current trend must be taken from counts at the larger colonies monitored periodically. In the Republic of Ireland, increases at some colonies are offset by decreases at others so there has probably been little change in numbers over the last decade. In Northern Ireland, numbers at the largest colony had declined by half in 2007 but this trend was entirely reversed in 2011. A survey of 25 razorbill colonies in 2015 resulted in a total of 31,115 individuals compared to 27,749 recorded during Seabird 2000, an increase of 16%. Some smaller islands were not counted which held c. 580 individuals during Seabird 2000. Hence, a large proportion of the national population was surveyed suggesting an increase of razorbill numbers for 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.

 

 

Population estimates and change 1969-2002 (census data)

 

 

Operation Seafarer    

(1969-70)

Seabird Colony Register    

(1985-88)

Seabird 2000    

(1998-2002)

Population estimate (Individuals) 897 848 1,524
% change since previous census    N/a -5 +80

 

Breeding abundance

 

Razorbill Calf of Man abundance 2015

Figure 1: Abundance of razorbill on the Calf of Man (Isle of Man), 1986-2015.

 

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. With few colonies surveyed since then, the status of the species is unknown. On the Calf of Man, which held between 20-25% of the razorbill population during the SCR and Seabird 2000 censuses, numbers show great variation over time. 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. In 2015, 73 individuals were recorded with counts done from sea and on land.

 

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.

 

 

Population estimates and change 1969-2002 (census data)

 

 

Operation Seafarer    

(1969-70)

Seabird Colony Register    

(1985-88)

Seabird 2000    

(1998-2002)

Population estimate (Individuals) 63 81 65
% change since previous census    N/a +29 -20

 

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 counted. There are no recent counts for the archipelago, so the status of razorbills in the Channel Islands is unknown. 

 

Productivity

 

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

 

 


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 rate

 

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 2015 presented here for Isle of May need to be treated as minimum estimates of survival of birds seen in 2014. In contrast, survival estimates do take into account birds that are not seen one year but which re-appear in following years.

 

Neither the annual return rate of razorbills  from the Isle of May (Figure 3) nor the survival rate from Skomer (Figure 4) show any clear trend over the period monitored, though low rates have been recorded in recent years (e.g. in 2007 and 2015 for Skomer birds and in 2008 and 2013 for Isle of May birds). Return rates on the Isle of May between 2009 and 2012 and in 2015 are among the highest recorded there.

 

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 follows a post-breeding 'wreck' of adult birds in the Skagerrak (the strait between Noway, Denmark and Sweden) and North Sea 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 be 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 contamination6. Overall, about 10% of the casualties were razorbills6. However, in Cumbria, 70% of 850 seabirds washed ashore dead or dying during this 'wreck' were razorbills7. 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 Ireland7. 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 sea6.

 

The effect of this 'wreck' on the razorbill populations of the UK and Ireland is starting to emerge. 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 worrying drop in the survival of adult breeding razorbills is clear, after a period of steady increase over the last 30 years. The survival of breeding adult razorbills during 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)8. 

Razorbill Isle of May returns 2015

 

Figure 3: Annual return rate of razorbills breeding on the Isle of May (North-east Fife), 1987-2015.

Razorbill Skomer survival 2015

Figure 4: Annual survival rate of razorbills breeding on Skomer (Dyfed), 1986-2014.

 


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, BTO, 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 Newton, S.  Lewis, L. and  Trewby, M. 2015. Results of a Breeding Survey of Important Cliff‐Nesting Seabird Colonies in Ireland 2015. National Parks and Wildlife Service Ireland.

6 Jessop, H. Seabird tragedy in the north-east Atlantic winter 2013/14. Unpublished report, RSPB, Sandy.

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

8 Stubbings, E.M., Büche, B.I., Miquel Riera, E., Green, R.M. and Wood, M.J. 2015. Seabird monitoring on Skomer Island in 2015.


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; 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 Environment Agency; 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.