Little Tern (Sternula albifrons) - Species Action Plan

Little terns are grey above and white below, with a black 'cap' and white forehead. They have orange-yellow legs, and a yellow bill with a black tip. They are Europe's smallest tern and one of Britain's rarest breeding seabirds. They are summer visitors to the UK, usually arriving in mid-April and leaving by September. Social nesting colonies are formed on sand and shingle beaches that offer good visibility for predator detection. There are several colonies in the UK, with little terns demonstrating a strong preference for nesting at beach sites on the Norfolk coast. Their diet consists of small fish and invertebrates collected from feeding areas not more than 3-4km from the breeding site.

Little terns lay two to three eggs in a shallow scrape in sand where their eggs are camouflaged among stones. Hatching occurs after 18-22 days and the young are able to leave the nest soon afterwards. Fledging is completed after 19-20 days.
Ref L/S4 Species Action Plan 4
Plan Author: RSPB (Philip Pearson)
Plan Co-ordinator: Coastal BAP Topic Group
Final June 2010
Plan Duration: June 2010 - May 2015

Little terns with chick
Little terns with chick (Photo credit: Kevin Simmonds)

Action Plan Summary

Current Status

National Status

Table 1: Population changes in British little tern colonies, and the proportion of the UK population supported by East Anglian and Norfolk colonies.

Year UK Population East Anglian Population Norfolk Population
Count % Change Count % Change % UK Count % Change % UK
Operation Seafarer (1969-1970) 1608   - - - 416 - 26
Seabird Colony Register (1984-1986) 2577 38 1256 - 49 508 18 20
Seabird 2000 (1998-2002) 1947 -24 1010 -20 52 600 15 31
  • Little tern colonies are widely but patchily distributed around the UK coast, with East Anglia being an important stronghold (Table 1).
  • National censuses show that the population in Britain declined by c. 25% between the mid-1980s and 2002 (Table 1). This rate of decline qualifies it for inclusion on the Birds of Conservation Concern Amber list, based on a moderate rate of decline.
  • Little tern is afforded some protection in the UK through its inclusion on Schedule 1 (part 1) of the Wildlife and Countryside Act 1981. In Europe, it is included in the Species of European Conservation Concern (SPEC) list, classified as SPEC 3, meaning moderate continuing decline. Little tern is also listed on Appendix 2 of the Bonn Convention, Annex 1 of the Birds Directive and Appendix 1 of the Bern Convention.
  • To maintain their numbers, little terns need to produce a five-year average of 0.67 chicks per pair (Ratcliffe 2003). Most UK little tern colonies have failed to reach this productivity target and are declining.

Norfolk Status

  • There are nine main sites in Norfolk where little tern regularly breeds: Great Yarmouth, Winterton, Eccles, Blakeney Point, Holkham NNR (comprising at least nine regular breeding areas, as identified in Table 2), Scolt Head Island, Brancaster, Titchwell and Holme (Fig. 1). In addition, 70 pairs bred at Horsey in 2000 (all records were of birds relaying after being displaced from other sites), whilst there is one record of two pairs breeding at Hickling Broad in 2003.
  • Annually, these Norfolk sites have supported at least one third of the UK little tern population (Table 2).
  • Increased pressure on beaches has led to a decline in the number of colonies, but not in the number of birds, and so the trend has been towards fewer, larger colonies. Some colonies are on 'second best' sites and may be more at risk from predation and tidal flooding. The North Dene Colony is also currently being squeezed into a smaller area of suitable habitat due to advancing dunes and beach scouring. It is not known whether this is a long term trend or a short term cycle.
  • Some Norfolk colonies have exhibited good productivity in recent years. For example: in 2003, productivities of 1.92 and 2.00 were recorded at Winterton and Eccles respectively, in 2006, North Denes achieved 1.82 chicks fledged per pair, and in 2008, the colony at Scolt Head Island achieved 1.21 chicks fledged per pair. These successful colonies help make up for less successful colonies elsewhere, boosting populations in Norfolk and at other UK sites. In the UK context, therefore, the Norfolk little tern population is highly important.

Table 2: Population changes in Norfolk little tern colonies between 2000 and 2009, and the proportion of the UK population that each colony represents. UK percentages are based on data collected from a sample of sites where regular monitoring of little tern populations is possible. This is likely to be an overestimate however, as some more remote colonies in other parts of the UK are not monitored on an annual basis. Data compiled from Mavor et al. 2002-2006, Dunmore 2000-2007 and the Seabird Monitoring Programme at: http://www.jncc.gov.uk/smp/Default.aspx - accessed 03/06/2009. (^ Sites comprised within Holkham NNR).

Site 2000 2001 2002 2003 2004
Pairs % UK Pairs % UK Pairs % UK Pairs % UK Pairs % Uk
Great Yarmouth 220 - 165 19 98 7 9 1 17 1
Winterton 19 - 24 2 124-160 9-12 233 18 150 12
Hickling Broad             2 <1    
Eccles         12 1 37 3 47 4
Blakeney 115 - 110 8 85 6 116 9 75 6
Burnham Overy - Stiffkey Binks ^ 81-86 -                
Stiffkey New East ^                    
Big Binks ^         1 <1     3 <1
Little Binks ^     11 1 22 2 4 <1    
Wells Breakthrough ^         3 <1        
Wells New Ridge ^     48 3 43 3 37 3 11 1
Bob Hall Sands ^     4 <1 2 <1 1 <1    
Wells ^     3 <1 16 1 4 <1 24 2
Holkham ^     25 2            
Burnham Overy-Holkham ^         36 3 33 3 26 2
Scolt Head 87 - 90-95 6-7 90-95 7 90 7 90-95 7-8
Brancaster 4   3 <1     3 <1 3 <1
Titchwell     1 <1 5 <1     4 <1
Holme 4 - 11 1 2 <1 15-16 1 9 1
Total 530-535 - 595-600 42 519-560 39-42 574-575 43 459-464 36-37

 

Site 2005 2006 2007 2008 2009
Pairs % UK Pairs % UK Pairs % UK Pairs % UK Pairs % Uk
Great Yarmouth 214 18 369 28 261-276 - 350 - 339 -
Winterton 9 1     54-83 - 9 - 87 -
Hickling Broad                    
Eccles 36 3     25 -        
Blakeney 50 4 56 4 68 - 101 - 86  
Burnham Overy - Stiffkey Binks ^         10 -        
Stiffkey New East ^                 7  
Big Binks ^         1 -        
Little Binks ^ 2 1 7 1 16 - 7 - 17 -
Wells Breakthrough ^         4 - 9 - 17 -
Wells New Ridge ^ 25 2 24 2 51 - 54 - 15 -
Bob Hall Sands ^     18 1 1 -     1 -
Wells ^ 18 2 1 <1            
Holkham ^                 10 -
Burnham Overy-Holkham ^ 17 1 32 2 28 - 28 - 28 -
Scolt Head 105 9 82 6 87-90 - 132 - 123 -
Brancaster 5 <1 2 <1 1   2      
Titchwell 3-5 <1                
Holme 12 1 11 1 5 -        
Total 496-498 41 602 46 612-659 - 692 - 730 -

back to top

Current factors influencing breeding success and survival

  • Disturbance: Little tern occupancy is significantly reduced in areas of high disturbance. In recent years, the East Anglian colonies have been affected significantly by a range of issues including beach users, dog walkers, vandalism and aircraft.
  • Predation: A large number of predators prey on little tern, of which, red fox Vulpes vulpes, carrion crow Corvus corone, common kestrel Falco tinnunculus and hobby Falco subbuteo are the main species. In addition, hedgehogs Erinaceous europaeus, mustelids, gulls, other birds of prey, stray dogs Canis familiaris and cats Felis catus have also been recorded raiding little tern colonies. Oystercatcher Haematopus ostralegus has also been seen killing chicks. Many of Norfolk's little tern colonies have experienced poor productivity or failed entirely due to high predation levels.
  • Prey availability: There is strong evidence that the success of little tern colonies is dependent on having a suitable food supply. Prey availability may be a key factor in colony establishment, but there is limited detailed research on this factor due to surveys being prohibitively expensive. Pre-construction surveys for the Scroby Sands wind farm, however, found that birds typically foraged relatively short distances from the shore: mean values of 38.4m to 139m at Great Yarmouth and mean distances of 277m to 319m at Winterton. It was therefore concluded that colonies should establish in close proximity to high quality, dense food sources.
  • The impact of offshore developments: Terns may be indirectly affected by the impacts of pile driving on fish prey resources, as reported from wind farms, notably Scroby Sands Wind Farm. Clupeids (mainly Atlantic herring Clupea harengus or European sprat Sprattus sprattus) are an important resource for terns for improving body condition for breeding, during nest development and during chick provisioning. Clupeids are known to be sensitive to underwater noise, owing to a configuration of hearing apparatus and swim bladder that enables clupeids to be 'hearing specialists'. This potentially renders clupeids vulnerable to lethal effects at close range and reports indicate that for herring, auditory damage may occur up to 3km away. Additionally, strong behavioural disturbance is likely over wider distances, up to 30km, whereby pelagic species such as herring are unlikely to return to their pre-piling locations. Herring spawn in the autumn in the Greater Wash region. Eggs and larvae, which are unable to disperse away from lethal sound levels, will be affected by piling during this period. This could potentially impact on reproduction, with uncertainties in respect to population size and age structure in future years. The impact on fish populations of activities other than piling that generate significant noise should also be considered.
  • The impact of commercial fisheries: The use of trawling gear, notably for brown shrimp Crangon crangon, may reduce prey availability through altering the seabed habitat and the capture of non-target species such as clupeids.
  • The impact of coastal development: The construction, maintenance and running of various coastal infrastructure, notably ports and wind farms, can impact on breeding species through increased disturbance (people, traffic, noise and light) and reduced prey availability. These effects could reduce the breeding density, breeding productivity, or cause the entire colony to relocate elsewhere.
    Coastal processes may also be impacted by construction. Altering sea currents can result in previously accreting beaches becoming eroded, thus the amount of breeding habitat can be considerably reduced. Prey availability may also be reduced if sand banks are lost.
  • Sea-level rise/coastal squeeze: Many colonies are facing an increasing risk of being washed out due to rising sea-levels, and a reduction in size of breeding beaches due to beach scouring and dune encroachment. This issue may become increasingly worse in the coming years if shoreline management policies do not allow foreshore and beaches to adapt and be resilient to climate change
  • More frequent storm events: Increased storm events in the future could act to reduce habitat availability.
  • Offshore dredging: Aggregate extraction within the Humber and Greater Wash marine area and the Norfolk Sandbanks could potentially affect adversely wildlife within an extraction area. Consequently, the prey resources and availability may be reduced, notably where this impacts on clupeid breeding areas.
  • Increased coastal access: The government is planning to designate the whole of the UK coastline as Open Access land. Unless planned for and managed, this could result in increased disturbance to little tern colonies around the Norfolk Coast, especially unprotected colonies with no wardening.
  • Egg collecting: At least one colony has suffered from probable egg collecting in the past ten years. Whilst many of the colonies have wardens and protection schemes in place, this is not for a full 24 hours in most cases, leaving the colonies vulnerable at night.
     

back to top

Current Action in Norfolk

  • Great Yarmouth North Denes Special Protection Area (which includes the beach at Winterton-Horsey Dunes SSSI) is designated solely for its breeding little tern colony.
  • Most little tern colonies are protected either within nature reserves or through wardening schemes. The North Denes colony currently has 24-hour protection during the breeding season, but all other colonies have wardens present for twelve-hours or less.
  • Colonies are fenced to keep human disturbance to a minimum. Electric fences are used to deter predators such as red fox.
  • Suitable shelters (for example, a camouflaged pipe partially buried in the sand) are positioned throughout most colonies for chicks to hide in. This affords the chicks greater protection from inclement weather conditions.
  • Research at the North Denes colony is investigating the effectiveness of diversionary feeding of kestrels to reduce their impact on chick survival.

back to top

Action Plan Objectives and Targets

National

  • Maintain a five-year average of 0.67 chicks per pair.

Norfolk

  • Ensure the overall Norfolk population does not drop below 650 pairs distributed among no less than fifteen sites (this includes approximately eight breeding areas considered part of the Holkham NNR). This should include maintaining the current annual population size at three established sites during the plan period (2010 - 2015): North Denes (320 pairs), Blakeney (85 pairs), and Scolt Head (95 pairs). Targets may be subject to change due to natural processes affecting site suitability.
  • Maintain current range of little tern in Norfolk (approximately twenty 1km squares), with North Norfolk supporting at least nine breeding colonies annually and East Norfolk supporting at least three breeding colonies annually.
  • Ensure that all colonies are achieving a five-year average productivity of at least 0.67 chicks per pair.

back to top