Species Action Plan
Grey Heron

“It can be asserted with a fair degree of certainty that neither the heron nor the spoonbill will ever again breed in London outside the Zoo.” (Fitter, 1949)

1.	Aims
•	To conserve London’s grey heron population by protecting existing and newly established heronries, roosting and foraging habitat.
•	To raise awareness of grey herons, their requirements and their value as an indicator of healthy rivers and water bodies.

2.	Introduction
Grey herons (Ardea cinerea) are easily recognised and appreciated by most Londoners and capture public imagination. However, despite their characteristic dark wings and black crest they are often mistakenly known as ‘stork’ or ‘crane’.
Herons are at the top of the food chain in freshwater habitats and their presence can indicate a healthy freshwater environment. Huge improvements in the water quality of the River Thames and its tributaries have provided a plentiful food source for herons, allowing them to increase and spread. London is a heron hotspot and in 1985 contributed about 1% of the United Kingdom population.
3.	Current Status
Grey herons breed colonially, usually at the tops of tall trees on islands that offer some degree of protection from disturbance. All London’s heronries are in such locations, with the exception of Lonsdale Road Reservoir where they nest on tern rafts.
The British Trust for Ornithology (BTO) Heronries Census provides excellent information on heron numbers, which are currently at their highest levels. During the last nationwide census in 1985, London had three heronries containing 114 nests. By 2000, this had gone up to 16 heronries with 302 nests. Heronries are found in the following London Boroughs: Bexley; Bromley; Hillingdon; Hounslow; Merton; Richmond; Waltham Forest; Wandsworth and City of Westminster (see Annex for map and further details). There are also two heronries (Kempton Park and Stocker’s Lake) just outside the Greater London boundary.
Nationally, the average size of heronries in England is about 18 nests (Marchant, 2000). The heronry at Walthamstow Reservoirs is one of the largest in the country, with 110 nests in 2000 – excluding this site, the average in London is 13. Recently established heronries demonstrate that new sites can be found in London, though the number of suitable locations for future heronries is limited. The only recent instance of a heronry failing to become established was at Kew Gardens (London Borough of Richmond), where two pairs nested between 1989 and 1991.

4.	Specific Factors Affecting the Species
4.1	Water Quality
The increase in heron numbers in London can be attributed to the improvement in water quality and the recent run of mild winters. The improvement in water quality has led to higher natural fish populations, augmented in some places by direct stocking. The continuing commitment to improvements in water quality is likely to lead to further increases in fish populations.
4.2	Severe Winters
The Heronries Census shows that severe winters have a major impact on heron numbers (Marchant et al., 1990). Numbers can decline sharply in severe winters and may recover to previous levels within five years. The last severe winter was in 1985/86.
4.3	Disturbance and Persecution
Despite their clear adaptation to busy urban environments, heronries, day roosts and foraging habitat remain vulnerable to disturbance from recreational and development activity. The most vulnerable period is while birds are sitting on eggs and it is often not realised that birds can be incubating as early as February.
Herons that visit garden ponds may not be welcomed by the owners. The extent of any persecution in London is unknown and is most likely to be a problem from individuals keeping expensive Koi carp. Discarded fishing line is also a threat to herons and other wildlife.
4.4	Cormorants
The increasing inland cormorant population may become a threat to herons if they compete for the same nesting sites. They began nesting at Walthamstow in 1990 and Broadwater in 1997 and by 2000, there were 240 and 15 nests respectively. At both sites, the herons and cormorants use different islands and at the moment there is no conflict.
4.5	Disease
Recently, a number of young at a heronry in Nottinghamshire hatched badly deformed and died in the nest (Blackburn & Kent, 1999). The cause of these deformities is unknown and the phenomenon has not been observed in London.

5.	Current Action
5.1	Legal status
The Wildlife and Countryside Act (1981, as amended) protects grey herons from killing and catching, being held in captivity, and the wilful destruction of their nests. It is possible to apply for a licence to kill birds where they are proven to cause serious damage at fisheries.
5.2	Mechanisms targeting the species
These current actions are ongoing. They need to be supported and continued in addition to the new action listed under Section 7.
5.2.1 Survey and monitoring
Each year, volunteers count the nests in London’s heronries for the BTO Heronries Census. The grey heron is included in the BTO/WWT/RSPB/JNCC Wetland Bird Survey (WeBS) and volunteers make monthly counts at many sites in London (see Annex 2).
5.2.2	Advice
The RSPB has produced a free advisory leaflet, ‘Herons and Garden Fish Ponds’ that gives advice on deterring herons from taking fish.

6.	Objectives, Actions and Targets
Most of these actions are specific to this species. However, there are other, broader actions that apply generically to a number of habitats and species. These are located in a separate ‘Generic Action’ section which should be read in conjunction with this document. There are generic actions for Site Management, Habitat Protection, Species Protection, Ecological Monitoring, Biological Records, Communications and Funding.
Please note that the partners identified in the tables are those that have been involved in the process of forming the plan. It is not an exclusive list and new partners are both welcomed and needed. The leads identified are responsible for co-ordinating the actions – but are not necessarily implementers.

Objective 1	Maintain the current number of heronries
Target: Between 15 and 20 heronries at the end of 2011

Action	Target Date	Lead	Other Partners	

1.1 Establish a Heron Working Group (HWG)	Achieved
2001	GLA	BTO, LA, LNHS, LWT, NT, RP, RSPB, TW, WWT, Syon Park	

1.2 Ensure HWG regularly meets to develop and share knowledge and information	Bi-Annually	GLA	BTO, LA, LNHS, LWT, NT, RP, RSPB, TW, WWT, Syon Park	
1.3 Protect trees in all current heronries where they may be threatened through appropriate methods such as park management plans or TPOs. This is to be encouraged via dialogue with land owners and managers following dissemination of best practice document	2007, Annually thereafter	LTOA	GLA, LA	
1.4 Produce best practice document for habitat improvements around heronries which includes information on minimising disturbance and appropriate habitat management for young	2005	Working Group	GLA	
1.5 Disseminate best practice document for habitat improvements around heronries which includes information on minimising disturbance and appropriate habitat management for young	2006	Working Group	GLA	

Objective 2	Develop and implement an ongoing research and monitoring programme
Target	: Establish monitoring programme and assess importance of day roosts by 2006

Action	Target Date	Lead	Other Partners	
2.1 Extract heron data from monthly WeBS counts	Achieved 2001	WWT	Volunteers	
2.2 Conduct research into the viability of artificial breeding platforms in current heronries where nesting sites are threatened	Achieved 2003	Working Group	LA, NT, RP, TW	
2.3 Count all heronries annually through BTO census	Ongoing	BTO	Volunteers	
2.4 Develop a programme to monitor breeding success at selected heronries	2004	BTO	Working Group	
2.5 Identify established day roosts and assess their importance	2006	WWT	Working Group, LA, LNHS, LWT	

Objective 3	Generate an awareness of grey herons and their requirements to the general public, as well as anglers, site owners/managers and planners
Target: Promote ways of resolving conflict with pond owners by 2004, and hold an annual Heron Day

Action	Target Date	Lead	Other Partners	
3.1 Promote RSPB leaflet on conflict between herons and garden pond owners through local authorities using libraries and other outlets	2004, Annually thereafter	RSPB	LA	
3.2 Hold a ‘Heron Day’ at several accessible sites, where the public can view heronries when young are in the nest	Annually	Working Group	LA, LWT, NT, RP, TW, WWT	

Relevant Action Plans
London Plans
Woodland; The Tidal Thames; Canals; Private Gardens; Reedbed; Grazing Marsh and Floodplain Grassland Audit; Marshland Audit; Ponds, Lakes and Reservoirs Audit; Rivers and Streams Audit.
National Plans
Coastal and Floodplain Grazing Marsh, Reedbeds, Eutrophic Standing Waters.

Key References
Blackburn, A & Kent, J (1999). Problems at a Heron colony. BTO News Number 224.
Fitter, RSR (1949). London’s Birds. Collins, London.
Gibbons, DW; Reid, JB & Chapman RA (1993). The New Atlas of Breeding Birds in Britain and Ireland: 1988-1991. T & AD Poyser, London.
Marchant, JH (2000). Herons in 1999. BTO News Number 228.
Marchant JH; Hudson R; Carter SP & Whittington P (1990). Population trends in British Breeding Birds. BTO.

Abbreviations
BTO – British Trust for Ornithology
GLA – Greater London Authority
JNCC - Joint Nature Conservation Committee
LA - Local Authorities
LNHS – London Natural History Society
LTOA – London Tree Officers Association
LWT – London Wildlife Trust	NT - National Trust
RP - Royal Parks
RSPB - Royal Society for the Protection of Birds TPO - Tree Protection Order
TW - Thames Water
WeBS - Wetland Bird Survey
WWT - Wildfowl and Wetland Trust	

Contact
The Lead for this species is Wandsworth Borough Council.
Valerie Selby
Principal Parks Officer (Biodiversity)
Wandsworth Borough Council
Ecology Office, Battersea Park, 
London SW11 4NJ.	Email vselby@wandsworth.gov.uk
Tel  020 7223 5831	

Annex 1
Map showing approximate size and location of heronries in London

Heronries map
Annex 2
List of Heronries in Greater London

Heronry	London Borough	Owner	Status	Year established	Number of nests	
			Statutory	SINC		1998	1999	2000	
Crossness Sewage Treatment Works	Bexley	TW		-	1996	11	9	11	
Kelsey Park	Bromley	LA		SBI2	1995	12	15	18	
Broadwater Gravel Pit	Hillingdon	Redlands		pSMI	1979	25	41	28	
Yiewsley Gravel Pit	Hillingdon			pSMI	1989	16	15	18	
Isleworth Ait	Hounslow	TW		pSMI	1991	7	5	7	
Osterley Park	Hounslow	NT		SBI1	1989	4	4	5	
Syon Park	Hounslow	Private	SSSI	pSMI	1989	2	1	1	
Morden Hall Park	Merton	NT		SBI1	1999		2	3	
Barn Elms Playing Fields	Richmond	LA		SBI2	2000			1	
Brentford Ait	Richmond	LA		pSMI	1991	22	20	23	
Corporation Island	Richmond	LA		pSMI	1998	5	11	11	
Lonsdale Road Reservoir	Richmond	LA	LNR	SBI1	1998	1	3	4	
Richmond Park	Richmond	RP	NNR, SSSI 	SMI	1994	25	7	13	
Walthamstow Reservoirs	Waltham Forest	TW	pSPA, SSSI	SMI	1916	126	100	110	
Battersea Park	Wandsworth	LA		SMI	1990	32	29	27	
Regent's Park	City of Westminster	RP		SMI	1968	25	24	22	
Totals	313	286	302	

Abbreviations: LNR - Local Nature Reserve, NNR - National Nature Reserve, SBI1 - Site of Borough Importance Grade 1, SBI2 - Site of Borough Importance Grade 2, SINC - Site of Importance for Nature Conservation, (p)SMI - (part of) Site of Metropolitan Importance, pSPA - proposed Special Protection Area, SSSI - Site of Special Scientific of Interest