Species Action Plans - Bittern
(Botaurus
stellaris)
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Click to view the Bittern Action Plan New plan available soon. |
Current Status
National Status
- Population increasing, but still localised and rare 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 has had a dramatic effect on 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 population in Norfolk increased from six males in 1995 to 19 in 2004, but has since suffered a marked drop. The number of breeding females, however, has stayed constant at around seven or eight for the last ten years.
- Table 1 presents the results of recent counts of booming males and nests
in Norfolk. These can be summarised as follows:
2004: Minimum of 19 and maximum of 26 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 ten and a maximum of 16 booming males, with a minimum of four and a maximum of five to six nests.
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 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 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.
Table 1: Summary of Norfolk counts of booming males and nests, 2004-2007.
| Site | Year | |||
| 2004 | 2005 | 2006 | 2007 | |
| BROADS | ||||
| Upper Ant | Up to 5 booming males; 5 of 6 nests failed. | 1 booming male; 2 nests. | 2 booming males; 2 nests. | 2 booming males; 1 nest failed. |
| Mid Ant | 1 strong and 1 weak booming male | 2 booming males; 1 nest. | 3 booming males. | 3 booming males. |
| Bure | 2 booming males. | 1 booming male; 1 nest. | 1 booming male. | 2 booming males; 1 successful nest. |
| Thurne | 8 booming males; at least 2 nests. | 3 booming males; 3 nests (2 successful). | 3 booming males; 2 nests. | 5+ booming males. |
| Yare | 1 booming male; 1 nest (failed). | 1 booming male. | 1 booming male. | 2 booming males; 1 nest not confirmed; 1 confirmed. |
| NORTH NORFOLK | ||||
| North Coast | 3 booming males; 2 successful nests. | 3 booming males; 1 nest. | 3 booming males. | 3 booming males; nests not confirmed. |
Source: RSPB
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. Management of water level control structures is key to providing seasonally correct water levels.
- 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 BA volunteers. In 1997, approximately three kilometres of dykes were mud pumped to improve water circulation and fish habitat. Since then, bittern have used the site every winter, but there have been no records of breeding behaviour. However, the site has been considerably improved as open fen with open water.
- 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 Buttles 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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