BTO - Breeding Birds of the Wider Countryside: Grey Heron

GREY HERON
Ardea cinerea

Conservation listings

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

Long-term trend

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

Distribution maps

Maps and statistics from British and Irish
atlases can be viewed here.

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, 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). The latest special survey of UK heronries, carried out in 2003 to mark the 75th anniversary of the Heronries Census, will revise the calibration of counts against the estimated breeding population sizes. A record total of more than 10,260 Grey Heron nests were counted in the UK in 2003.

Table of population changes for Grey Heron

Source	Period (yrs)	Years	Plots (n)	Change (%)	Lower limit	Upper limit	Alert	Comment
Heronries UK	73	1929-2002	282	70	.	.
	25	1977-2002	422	19	.	.
	10	1992-2002	465	13	.	.
	5	1997-2002	514	9	.	.
Heronries England and Wales	73	1929-2002	236	75	.	.
	25	1977-2002	332	20	.	.
	10	1992-2002	373	15	.	.
	5	1997-2002	406	8	.	.
Heronries England	73	1929-2002	201	73	.	.
	25	1977-2002	268	23	.	.
	10	1992-2002	310	15	.	.
	5	1997-2002	341	7	.	.
Heronries Scotland	48	1954-2002	35	84	.	.
	25	1977-2002	53	7	.	.
	10	1992-2002	53	16	.	.
	5	1997-2002	71	19	.	.
Heronries Wales	67	1935-2002	38	21	.	.
	25	1977-2002	64	4	.	.
	10	1992-2002	63	17	.	.
	5	1997-2002	65	9	.	.
BBS UK	9	1994-2003	494	40	26	56		Non-breeders included
BBS England	9	1994-2003	399	23	10	38		Non-breeders included
BBS Scotland	9	1994-2003	41	110	38	218		Non-breeders included
BBS Wales	9	1994-2003	38	47	1	114		Non-breeders included

Table of productivity information for Grey Heron

Variable Period
(yrs) Years Mean
annual
sample Trend Predicted
in first year Predicted
in last year Change Comment

Brood size 34 1968-2002 44 None

Daily failure rate (eggs) 34 1968-2002 15 None Small sample

Daily failure rate (chicks) 34 1968-2002 28 Linear decline 0.058 nests/day 0.0006 nests/day -0.0574 nests/day Small sample

Laying date 34 1968-2002 30 Linear decline day 98 day 72 -26 days

Insufficient data on CES
available for this species


	BTO Home \| JNCC Home BTO, The Nunnery, Thetford, Norfolk IP24 2PU, UK. © British Trust for Ornithology (Registered Charity Number 216652). Terms and Conditions \| Privacy Statement Email:
This report should be cited as: Baillie, S.R., Marchant, J.H., Crick, H.Q.P., Noble, D.G., Balmer, D.E., Beaven, L.P., Coombes, R.H., Downie, I.S., Freeman, S.N., Joys, A.C., Leech, D.I., Raven, M.J., Robinson, R.A. and Thewlis, R.M. (2005) Breeding Birds in the Wider Countryside: their conservation status 2004. BTO Research Report No. 385. BTO, Thetford. (http://www.bto.org/birdtrends) Pages maintained by Susan Waghorn and Iain Downie: Last updated 18 January, 2006