BTO - Breeding Birds of the Wider Countryside: Grey Heron

GREY HERON
Ardea cinerea

• Population
changes

• Productivity
trends

• Additional
information

Conservation listings

Europe: no SPEC category (favourable conservation status in Europe, not concentrated in Europe)
UK: green

Long-term trend

UK, England: moderate increase
Wales, Scotland: shallow increase

UK population size

14,200 nests in 2003 (Heronries Survey 2003: APEP06); 13,700 (13,200–14,600) nests in 2005 (Heronries Census)

Status summary

The BTO Heronries Census, which has monitored Grey Herons since 1928, shows the species to be more abundant now than ever before. The effects of harsh winters, which induce severe mortality in this species (Besbeas et al. 2002), are clearly visible in the long-term trend. The general increase that underlies these fluctuations may stem from reduced persecution, improvements in water quality, the provision of new habitat as new lakes and gravel pits mature, and increased feeding opportunities at freshwater fisheries (Gibbons et al. 1993, Marchant et al. 2004). High rates of nest failure at the chick stage were noted in the late 1960s, but not subsequently. The mean laying date has advanced by almost a month since 1968. In the latest special survey of UK heronries, carried out in 2003 to mark the 75th anniversary of the Heronries Census, a record total of more than 10,337 Grey Heron nests were counted. The current population estimates for that year, implying that almost 4,000 nests in the UK were not reported to the survey, allow for known heronries (mostly in Scotland) that were not visited in 2003, but not for the few areas, mainly in Scotland and Northern Ireland, where heronries have never been counted. This issue was addressed by random tetrad searches conducted in 2003 and 2004.

Population changes

Herons UK graph

Table of population changes for Grey Heron

Source	Period (yrs)	Years	Plots (n)	Change (%)	Lower limit	Upper limit	Alert	Comment
Heronries UK	76	1929-2005	307	63	29	91
	25	1980-2005	475	17	8	26
	10	1995-2005	555	7	2	13
	5	2000-2005	577	-1	-5	3
Heronries England and Wales	76	1929-2005	255	69	31	98
	25	1980-2005	390	18	11	25
	10	1995-2005	456	6	3	12
	5	2000-2005	473	-1	-4	4
Heronries England	76	1929-2005	216	68	25	100
	25	1980-2005	320	21	11	31
	10	1995-2005	386	7	3	14
	5	2000-2005	401	-1	-4	4
Heronries Scotland	70	1935-2005	43	24	.	.
	25	1980-2005	70	36	.	.
	10	1995-2005	84	50	.	.
	5	2000-2005	89	19	.	.
Heronries Wales	70	1935-2005	40	10	.	.
	25	1980-2005	65	0	.	.
	10	1995-2005	66	2	.	.
	5	2000-2005	69	-8	.	.
BBS UK	10	1995-2005	562	19	7	33		Non-breeders included
	5	2000-2005	646	4	-3	11		Non-breeders included
BBS England	10	1995-2005	453	12	1	27		Non-breeders included
	5	2000-2005	521	11	3	20		Non-breeders included
BBS Scotland	10	1995-2005	46	44	10	92		Non-breeders included
	5	2000-2005	48	-1	-17	16		Non-breeders included
BBS Wales	10	1995-2005	43	3	-19	37		Non-breeders included
	5	2000-2005	51	-8	-19	11		Non-breeders included

Census of England graph

Census of England & Wales graph

Census of Scotland graph

Census of Wales graph

BBS UK graph

BBS England graph

BBS Scotland graph

BBS Wales graph

Productivity trends

Table of productivity changes for Grey Heron

Variable	Period (yrs)	Years	Mean annual sample	Trend	Modelled in first year	Modelled in 2005	Change	Comment
Brood size	37	1968-2005	46	None
Daily failure rate (eggs)	37	1968-2005	15	None				Small sample
Daily failure rate (chicks)	37	1968-2005	26	Linear decline	5.78% nests/day	0.04% nests/day	-99.3%	Small sample
Laying date	37	1968-2005	27	Linear decline	Apr 8	Mar 11	-28 days	Small sample

Clutch size graph

Brood size graph

Egg nest failure graph

Chick nest failure graph

Laying date graph

Insufficient data on CES
available for this species

Additional information


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This report should be cited as: Baillie, S.R., Marchant, J.H., Crick, H.Q.P., Noble, D.G., Balmer, D.E., Barimore, C., Coombes, R.H., Downie, I.S., Freeman, S.N., Joys, A.C., Leech, D.I., Raven, M.J., Robinson, R.A. & Thewlis, R.M. (2007) Breeding Birds in the Wider Countryside: their conservation status 2007. BTO Research Report No. 487. BTO, Thetford. (http://www.bto.org/birdtrends) Pages maintained by Susan Waghorn and Iain Downie: Last updated 3 January, 2008