Bittern (Botaurus stellaris) - Species Action Plan

Ref 1/S6 Species Action Plan 6
Plan Author: RSPB
Plan Co-ordinator: Wetlands BAP Topic Group
Plan Leader RSPB
Final Draft 31 December 1998
Revised Final Plan 3 February 2009

Action Plan Summary

Current Status

National Status

  • Although its population is increasing, the bittern is still rare and localised in the UK. The UK population had declined to about 14 booming males in 1997 from a peak of 70 booming males in the late 1960s. However, work completed through two separate EU LIFE projects had a dramatic effect on the population, with 55 booming males recorded in 2004. Numbers are also boosted in winter by continental immigrants.
  • The bittern is listed on Annex I of the EC Birds Directive and Appendix II of the Berne Convention. It is protected in the UK under Schedule 1 of the WCA 1981. It is a Red List species, having declined by over 50% in the last 25 years.

Norfolk Status

  • The bittern breeds in north Norfolk and the Norfolk Broads. The bittern also over-winters on other reedbeds in Norfolk, e.g., along the Wensum and at Bowthorpe and Guist.
  • The results of recent counts of booming males and nests in Norfolk are summarised below:

    2004: Minimum of 19 and maximum of 25 booming males, with nine nests.
    2005: Minimum of 11 and maximum of 11 booming males, with a minimum of seven and a maximum of eight nests.
    2006: Minimum of 13 and a maximum of 16 booming males, with six nests.
    2007: Minimum of thirteen and a maximum of 20 booming males, with a minimum of four and a maximum of six nests.
    2008: Minimum of 25 and maximum of 29 booming males.

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Current factors causing loss or decline

The main factors limiting successful breeding of bittern within the Broads and Norfolk coast are:

  • Lack of sufficient food in some areas during the breeding season; and
  • Inappropriate water level management and control within suitable breeding sites.

Additional factors which are likely to be leading to loss or decline include:

  • Loss of suitable breeding areas in fens and reedbeds through natural succession and lack of appropriate management (particularly cutting and water management);
  • Degradation of habitat quality through eutrophication;
  • Salt water intrusion into coastal reedbeds and threat of habitat loss due to sea level rise and isostatic land movements;
  • Vulnerability to severe winter weather.

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Current Action in Norfolk

  • All remaining bitterns breed on SSSIs, most of which are managed as nature reserves. Specific annual management activities carried out include cutting of reed and sedge, clearance of invading scrub and maintenance of open ditches and pools. Currently, management of water level control structures is key to providing seasonally correct water levels; in future, it would be desirable to move towards more naturally functioning floodplains.
  • During 1995 and 1996, English Nature mechanically removed scrub from 26ha of the 30ha Hoveton marshes (outside but adjacent to Bure Broads & Marshes SSSI), at a cost of £58,000 and with the help of Broads Authority volunteers. In 1997, approximately three kilometres of dykes were mud pumped to improve water circulation and fish habitat. Since then, bitterns have used the site every winter, but there have been no records of breeding behaviour. The site was considerably improved by creation of open fen with open water features; however, re-growth of scrub requires further action at this site.
  • Another project was carried out by English Nature and the Broads Authority at Bure Marshes NNR in 1999, when 4.7 ha of old reedbed were lowered by the BA digger. This created a revitalised reedbed with permanent standing water (with improved connectivity to the River Bure), including 0.6 ha of open water. This has been used since by bitterns for wintering and feeding during the summer, and was the final increase to the area of suitable habitat within the middle Bure which is now used by breeding bittern.
  • More recently, management work has been carried out in Norfolk by EN, RSPB, BA and NWT to benefit bittern as part of two nationally developed EU LIFE projects. The key aims of the second LIFE project (which ended in 2006) were to: increase the number of fledged young produced; provide fledglings with suitable sites to move on to; and provide more suitable sites for wintering bitterns both from home and abroad.
  • Most work on the LIFE projects involved improving water level control, restoring degraded reedbeds either by cutting or lowering the bed surface, and creating suitable habitat for fish and other aquatic life that is likewise accessible for bittern. Key sites included in the LIFE projects were NWT reserves at Holme, Cley and Hickling, RSPB reserves at Titchwell and Strumpshaw and BA's Buttle marsh adjacent to How Hill.
  • RSPB continues to carry out detailed ecological studies of bitterns including annual mapping of booming males and active nest sites to inform successful breeding.

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Action Plan Objectives and Targets

National

  • Increase the number of booming male bitterns to 60 in the UK by 2010.
  • Increase the number of sites supporting booming male bitterns in the UK to 32 by 2010.
  • Increase the number of booming male bitterns in the UK on inland sites (i.e. sites not at risk from saline intrusion) to 24 by 2010.
  • Restore bittern range to >4 occupied 10km squares in Wales by 2020.

Norfolk

  • Increase the Norfolk population to at least 20 booming males and at least 15 nests by 2010 and 25 booming males and 20 nests by 2015.
  • Maintain the number and quality of sites currently holding breeding bitterns in Norfolk at eight.
  • Increase the number of sites holding breeding bitterns to ten by 2010 and 13 by 2015.
  • Ensure appropriate water level management and quality at all priority Norfolk sites listed in Table 1 below, in order to secure key nesting and feeding areas.
  • Create at least 100ha of habitat suitable for bitterns (in blocks greater than 20ha) by 2015. This is in addition to any wetland habitat that may be created to compensate for losses related to sea level rise.

Table 1: Key Norfolk reedbed sites capable of supporting breeding bittern.

Site Name Grid Ref SSSI Name
Barton Fen TG360236 Ant Broads and Marshes SSSI
Bure Marshes TG355159 Bure Broads and Marshes SSSI
Burnham Overy TF854450 North Norfolk Coast SSSI
Catfield fen TG370210 Ant Broads and Marshes SSSI
Cley Marshes TG055445 North Norfolk Coast SSSI
Hickling Broad
(incl. Heigham)
TG420200 Upper Thurne Broads and Marshes SSSI
Horsey Mere TG456205 Upper Thurne Broads and Marshes SSSI
How Hill TG372190 Ant Broads and Marshes SSSI
Martham Broad TG456205 Upper Thurne Broads and Marshes SSSI
Ranworth Flood TG370150 Bure Broads and Marshes SSSI
Sharp Street Fen TG370200 Ant Broads and Marshes SSSI
Strumpshaw Fen TG335064 Yare Broads and Marshes SSSI
Sutton Fen
(incl. Sutton High Fen)
TG364189 Ant Broads and Marshes SSSI
Titchwell TF752445 North Norfolk Coast SSSI
Upton Fen TG389134 Upton Broad and Marshes SSSI
Number of Sites = 15    

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