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Little tern (Sternula albifrons)

The following has been adapted from original text by Georgina Pickerell in Seabird Populations of Britain and Ireland (with permission from A&C Black, London).

 

Little tern is the smallest species of tern breeding in the UK, nesting exclusively on the coast in well-camouflaged shallow scrapes on beaches, spits or inshore islets. They do not forage far from their breeding site, which dictates a necessity for breeding close to shallow, sheltered feeding areas where they can easily locate the variety of small fish and invertebrates that make up their diet. Colonies are found around much of the coastline, but the main concentration is in south and east England, where the species' preference for beaches also favoured by people makes it vulnerable to disturbance.

Conservation status

Little tern is currently identified as a conservation priority in the following:

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International importance

UK Population

Biogeographic Population

% World Population

1,900 AON*

25.9 (ssp. albifrons)

2.2

*AON = Apparently Occupied Nests

The UK population figure (rounded to the nearest hundred) and the World populations were 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. The source for the Biogeographic population is AEWA CSR7.

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

Complete coverage of little tern colonies has been achieved in each national census. Site fidelity can be low from year to year, in response to predation, disturbance or habitat change. Thus, in order to gain an accurate national estimate of numbers, a simultaneous census was planned to cover all British colonies within a single year. During Seabird 2000, 93% of the population were counted in 2000, a marked improvement on the SCR Census when counts were spread over four years (13% counted in 1985, 21% in 1986, 63% in 1987 and 3% in 1988). There are no known colonies in Northern Ireland.

While the similarity in methods employed in both the SCR Census and Seabird 2000 ensures a valid comparison of their population estimates, the apparent population trend from a comparison of two such widely spaced surveys may be misleading. This is because the proportion of adult little terns choosing to nest in any one year fluctuates. Thus, more accurate trends are obtained from more frequently conducted counts (e.g. annually). Annual monitoring of little tern colonies has been conducted in Britain since 1969 with the colonies monitored currently holding about two-thirds of the national population.

 

Operation Seafarer    

(1969-70)

Seabird Colony Register    

(1985-88)

Seabird 2000    

(1998–2002)

UK Population estimate (AON*)

1,589

2,517

1,927

% change since previous census   

n/a

+58

-23

*AON = Apparently Occupied Nests

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 Little tern found in different regions, and a map showing the locations and size of colonies, is provided in the Seabird 2000 little tern 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 estimated reproductive success (hereinafter referred to as productivity) are only shown if data analysis 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.

Note: for clarity, the Figure 1 ‘Overview of all regions’ abundance graph does not include confidence limits. These can be found in the respective regional accounts below.

 

Overview of all regions

Breeding abundance

AF summary abundance.jpg

Figure 1. Trends in abundance index of little tern 1986–2019 for the UK (red), Scotland (blue) and England (black). Further details, including 95% confidence limits, can be found in the sections below. Based on SMP data; view the methods of analysis.

 

A large proportion of the colonies monitored for little tern abundance are in England and, consequently, the UK and English trends are closely matched. Similar to the UK and England, the Scottish trend has been decreasing since monitoring began in 1986, although has fluctuated more. For most of the monitoring period, the three trends have remained below the baseline.

More detailed information can be found in the individual country sections below. Little tern breed in all areas covered by this report apart from the Channel Islands and Northern Ireland; however, there are only a sufficient number of colonies monitored frequently to allow the production of meaningful abundance trends for the UK, England, and Scotland.

 

Productivity

AF summary productivity.jpg

Figure 2. Trends in productivity of little tern 1986–2019 for the UK (red), Scotland (blue), and England (black). Further details can be found in the sections below. Based on SMP data; view the methods of analysis.

 

A large proportion of the colonies monitored for little tern productivity are in England and, consequently, the UK and English trends are closely matched. Little tern productivity trends in the UK, England and Scotland have fluctuated throughout the monitoring period and there are no apparent trends.

There are only a sufficient number of colonies monitored frequently to allow the production of meaningful productivity trends for the UK, England, and Scotland.

 

United Kingdom

Breeding abundance

AF UK abundance.jpg

Figure 3. Trend in UK abundance index (solid line) of little tern 1986–2019 with 95% confidence limits (dotted lines). Based on SMP data; view the methods of analysis.

 

Figure 3 shows that little tern abundance in the UK declined overall from the late 1980s to 2005 but then increased, showing signs of a partial recovery, until 2012. In 2019, however, the index was 42% below the baseline, the lowest value recorded during the SMP monitoring period. Prior to this, little tern abundance had been in decline since the mid-1970s1, following increases during the early 1970s. The decline in numbers since 1986 has coincided with low productivity (see below), which is likely to have contributed to the decrease in abundance via low rates of recruitment into the breeding population.

 

Productivity

AF UK productivity.jpg

Figure 4. Trend in UK productivity (no. of chicks fledged per pair) of little tern 1986–2019. Based on SMP data; view the methods of analysis.

 

The productivity of little terns has been relatively low throughout the recording period, although with considerable annual fluctuation since the lowest value was recorded in 1991. These low levels of productivity are insufficient to maintain the population by recruitment alone. Simple population models, incorporating annual productivity estimates with constant values for adult survival and age at first breeding, have predicted the observed decline in population size reasonably accurately2. In 2019, the number of chicks fledged per pair was 0.56.

Factors contributing to this low productivity include predation of chicks and eggs by foxes Vulpes vulpes, kestrels Falco tinnunculus and corvids; nest loss due to bad weather; food shortage; and, most significantly, disturbance by humans. Most little terns nest along the east and south coasts of England, adjacent to some of the most densely populated areas of Britain, although many sites are now guarded in an attempt to limit disturbance. As little terns nest on low-lying ground close to the high water mark, their nests are also vulnerable to erosion and tidal inundation, hence much work has been done on site management to provide safe nesting areas. Predictions of increased storminess and sea-level change under climate change scenarios may lead to increased prevalence of such events, although managed realignment3 of coastal defences may create new opportunities for nesting.

 

Scotland

Population estimates and change 1969–2002 (census data)

 

Operation Seafarer    

(1969-70)

Seabird Colony Register    

(1985-88)

Seabird 2000    

(1998–2002)

Population estimate (AON*)

308

373

331

% change since previous census   

n/a

+17

-11

*AON = Apparently Occupied Nests

 

Breeding abundance

AF Scot abundance.jpg

Figure 5. Trend in Scotland abundance index (solid line) of little tern 1986–2019 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 Scottish little tern population increased between Operation Seafarer and the Seabird Colony Register but had fallen again by the Seabird 2000 census. The trend has been gradually decreasing since monitoring began and has remained below the baseline since 1989. However, as the confidence limits are wide, the trend should be interpreted with caution. In 2019, the index was 48% below the baseline.

Data from two of the largest and most frequently monitored colonies in Scotland indicate contrasting fortunes. At Sands of Forvie, numbers in 2019 (28 AON) were similar to when monitoring began in 1986 (29 AON), whereas at Tiree Reef numbers have declined from 54 AON in 1987 to 10 AON in 2019. Sands of Forvie has benefited from an electric fence which has kept out the majority of ground predators since the late 1980s (Anabel Drysdale pers. Comm.).

 

Productivity

AF Scot productivity.jpg

Figure 6. Trend in productivity (no. of chicks fledged per pair) of little tern in Scotland, 1986–2019. Based on SMP data; view the methods of analysis.

 

Aside from obvious peaks in 1999, 2009 and 2014, little tern productivity at Scottish colonies has usually been low and in line with that recorded in England. Low productivity is due to a variety of factors such as predation, poor weather, disturbance, and tidal inundation, and may be too low to sustain the population without emigration from colonies in other countries. In 2014, little terns had a very productive breeding season, while in 2015 productivity fell to the third lowest value on record. At Sands of Forvie, little terns attempted to breed in 2019 but failed to produce any fledged young (0.50 chicks fledged per pair in 2018), with all chicks failing at egg stage due to a combination of poor weather and avian predation, including oystercatcher Haematopus ostralegus and black-headed gull3,4.

 

England

Population estimates and change 1969–2002 (census data)

 

Operation Seafarer    

(1969-70)

Seabird Colony Register    

(1985-88)

Seabird 2000    

(1998–2002)

Population estimate (AON*)

1,247

2,087

1,521

% change since previous census   

n/a

+67

-27

*AON = Apparently Occupied Nests

 

Breeding abundance

AF Eng abundance.jpg

Figure 7. Trend in abundance index (solid line) of little tern in England, 1986–2019 with 95% confidence limits (dotted lines). Based on SMP data; view the methods of analysis.

 

The trend shown for the UK closely matches that for England, where the majority of data have been collected over the years. The declining trend for little terns in England, visible since 1987, has been slowed in recent years, no doubt through targeted management with many colonies now benefiting from some form of guarding, e.g. fencing, trapping, signage, surveillance, and public relations.

Prior to this, a large increase, of 67%, occurred between Operation Seafarer and the Seabird Colony Register. Currently, the total population in England is probably below that recorded during Seabird 2000 (1,521 AON), with 784 AON being recorded in 2019, although data are not submitted to the SMP for all colonies.

 

Productivity

AF Eng productivity.jpg

Figure 8. Trend in productivity (no. of chicks fledged per pair) of little tern in England, 1986–2019. Based on SMP data; view the methods of analysis.

 

Productivity recorded at English colonies has fluctuated markedly over the years but generally lies between 0.30–0.50 chicks fledged per pair per year; a fairly low value compared to e.g. Wales. As with Scotland, this level of productivity is probably insufficient to sustain population levels and probably contributes to the decline in the abundance trend.

Data from monitored colonies illustrate just how disastrous recent breeding seasons have been. Between 2017 and 2019, data were received from 27 colonies each year, with 10 of these not holding any breeding little terns and at least six of the remaining colonies failing completely. The reasons for these failures were high tides, poor weather, disturbance, and the predation of eggs, chicks and adults by mammals and other birds.

 

Wales

Population estimates and change 1969–2002 (census data)

 

Operation Seafarer    

(1969-70)

Seabird Colony Register    

(1985-88)

Seabird 2000    

(1998–2002)

Population estimate (AON*)

28

55

75

% change since previous census   

n/a

+96

+36

*AON = Apparently Occupied Nests

 

Breeding abundance

AF Wales Gronant abundance.jpg

Figure 9. Abundance of little terns at Gronant, 1986–2019.

 

Although the little tern population in Wales increased between each of the national censuses, the number of colonies since Seabird 2000 has declined from four to only two. At Gronant, numbers have fluctuated over the years, but the overall trend has been upward, possibly due to successful breeding seasons and subsequent increased recruitment into the colony. In recent years, the colony has consistently held four times the number of AON it did in 1986. 162 AON were recorded in 2019, while the only other Welsh colony, at Point of Ayr, held 3 AON.

 

Productivity

At Gronant, an average of 1.01 chicks per pair were fledged each year between 1986 and 2019. Peaks in productivity were recorded in 1992, 2003, 2004 and 2010, all ranging between 1.78 and 1.92. In 2019, productivity was 1.27 chicks fledged per little tern pair.

 

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 (AON*)

6

2

0

% change since previous census   

n/a

-67

-100

*AON = Apparently Occupied Nests

 

Breeding abundance

Six little tern AON were recorded during Operation Seafarer, declining to two by the time of the Seabird Colony Register, with none recorded during Seabird 2000. No little terns have been recorded breeding in Northern Ireland since then.

 

Productivity

No systematic data on the productivity of little terns in Northern Ireland were submitted to the SMP before the species ceased to breed in the country.

 

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 (AON*)

309

280

206

388

% change since previous census   

n/a

-9

-26

+39

*AON = Apparently Occupied Nests

 

Breeding abundance

AF RoI Kilcoole abundance.jpg

Figure 10. Abundance of little terns at Kilcoole, 1986–2019.

 

The little tern population in the Republic of Ireland declined 33% between the Operation Seafarer and Seabird 2000 censuses. While guarding colonies has succeeded in halting the population decline of little terns, their reduction in range has continued. Their vulnerability to disturbance has seen a shift towards fewer, larger colonies in areas where they are free from human disturbance, mostly in fenced off areas or on offshore islands3. Since the SCR, only the colony at Kilcoole, which accounts for over one third of the national population, has been monitored regularly (Figure 10). Numbers there trebled from 18 to 56, after the Seabird Colony Register census but had declined again to 20 AON by Seabird 2000. In 2019, Kilcoole had increased again to 162 AON reflecting the recent Republic of Ireland Seabird Census which recorded 388 little tern AON, an increase of 123% compared to Seabird 20006.

 

Productivity

An average of 0.88 little tern chicks were fledged per pair between 1986 and 2019 in the Republic of Ireland. In 2018, Kilcoole fledged 1.17 chicks per pair after surges associated with Storm Hector destroyed 45 nests. However, many of these pairs re-laid and successfully reared late chicks through to fledging7. For the first time in three years, little terns bred again at Baltray in 2018, fledging 0.75 chicks per pair8. In 2019, the average across four colonies was 0.63 chicks fledged per pair.

 

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 (AON*)

315

282

206

% change since previous census   

n/a

-10

-27

*AON = Apparently Occupied Nests

 

Breeding abundance

Little terns only breed in the Republic of Ireland, so all data and text presented for that country is also pertinent to the situation for the whole of Ireland.

 

Productivity

Little terns only breed in the Republic of Ireland, so all data and text presented for that country is also pertinent to the situation for the whole of Ireland.

 

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 (AON*)

19

60

20

28

% change since previous census   

n/a

216

-67

+40

*AON = Apparently Occupied Nests

 

Breeding abundance

The Isle of Man little tern population has never been large, with only 19 AON recorded at the time of Operation Seafarer. Three times as many were present during the Seabird Colony Register, with the peak count of 94 AON occurring shortly after this in 1988, although had fallen to 20 AON by Seabird 2000. In 2013, trapping of nesting adults resulted in four controls which had fledged as juveniles in 2010; three from other colonies around the Irish Sea and one from a colony on the east coast of Scotland. Immigration may, therefore, be one factor driving the increase in numbers. A seabird census of the Isle of Man between 2017-18 recorded 28 AON, a 40% increase compared to Seabird 20009. No abundance data was submitted to the SMP for 2019.



Productivity

Few systematic data on the productivity of little terns on the Isle of Man have been collected as part of the SMP.

 

Channel Islands

Little tern does not breed on the Channel Islands.

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UK phenology, diet, survival rates

No data have been collected as part of the Seabird Monitoring Programme.

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References

1 Ratcliffe, N., Pickerell, G. and Brindley, E. 2000. Population trends of Little and Sandwich Terns Sterna albifrons and S. sandvicensis in Britain and Ireland from 1969 to 1998. Atlantic Seabirds, 2, 211–26.

2 Ratcliffe, N. 2003. Little terns in Britain and Ireland: estimation and diagnosis of population trends. In: Schmitt, S. ed. Abstracts Proceedings. 2003 Little Tern Symposium. Royal Society for the Protection of Birds, Sandy.

3 Rendell-Read, S. 2018. Little Tern Newsletter 2017. Unpublished RSPB report, Royal Society for the Protection of Birds, Sandy.

4 Macleod-Nolan, C. 2020. Little Tern Newsletter 2019. Unpublished RSPB Report, Royal Society for the Protection of Birds, Sandy.

5 Rendell-Read, S. 2015. Little Tern Newsletter 2016. Unpublished RSPB report, Royal Society for the Protection of Birds, Sandy.

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 Johnson, C., Forkan, C. and Newton, S. 2018. Tern Colony Management and Protection at Kilcoole 2018. Conducted under services contract awarded to BirdWatch Ireland by the National Parks and Wildlife Service, Department of Culture, Heritage and the Gaeltacht.

8 Lynch, J, Hartigan, D, Connaghy, M. Martin, B, and Newton, S.F. 2017. Baltray Little Tern Colony Report 2017. Report by Birdwatch Ireland and Louth Nature Trust.

9 Hill, R.W., Morris, N. G., Bowman, & 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.

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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; Department of Agriculture, Environment and Rural Affairs (Northern Ireland); Department of Environment, Food and Agriculture (Isle of Man); Department of the Environment, Climate and Communications (Republic of Ireland); JNCC; Manx Birdlife; Manx National Heritage ; The National Trust; National Trust for Scotland; Natural England; Natural Resources Wales; NatureScot; The Royal Society for the Protection of Birds; Scottish Wildlife Trust; Seabird Group; Shetland Oil Terminal Environmental Advisory Group; States of Guernsey Government; UK Centre for Ecology and Hydrology. More about the SMP partners >>

 

Image of Little tern 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 1986–2019

Published: .

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