Grey Heron – Winter 2021

Ardea cinerea – CREYR GLAS – Breeding resident

Herons disperse widely in the autumn, and small parties of juveniles have been seen flying due west out to sea. Thus, the herons seen on the estuary system in winter may or may not be from local colonies. On WeBS sites, the total numbers drop from around 30-40 in autumn to around twenty in mid-winter.

The overall population trend seems to be for an increase in all parts of the UK for breeding herons, and a general increase in wintering herons except in Wales where there has been a slow decline since 2001-02. The results of WeBS in Pembrokeshire is consistent with this.

Distribution

This map was produced by the West Wales Biodiversity Information Centre using data collected between November and February for the BTO Atlas 2007-11, with additional data collected in 2011-12 winter to fill gaps in coverage.

The main sites are:

While herons can be found at almost any wetland (open water or marshy grassland) sites in winter, they are probably most easily observed on the estuaries and at Bosherston Lily Ponds.


Wetland Bird Survey

Herons were not regularly counted for WeBS until 1993.

Data for June and July are collected by Jane Hodges during the annual surveillance of summer shelduck populations on the Cleddau Estuary complex. There are no counts in August. The September to March data is collected from sites across Pembrokeshire (including the Teifi Estuary) for the BTO Wetland Bird Survey.

Maximum counts are usually in the autumn, coinciding with dispersal from nest sites. This graph will be updated as more counts come in.


Pattern of occurrence

Cumulative number of records per week in Pembrokeshire since 2000, taken from BirdTrack. As herons are considered to be a resident species, they can be seen at any time of year. However, sightings peak in September-October, coinciding with autumn dispersal.

Annie Haycock (BBS & WeBS local organiser)

HODGES J E. (2010-2020) Daugleddau Estuary and Milford Haven Waterway: annual surveillance of summer shelduck populations. Reports to the Milford Haven Waterway Environmental Surveillance Group.

More about the Grey Heron in Pembrokeshire

Grey Heron – 2003-07 breeding

Ardea cinerea – CREYR GLAS – Breeding resident.

Comparison with previous atlas:

1984-882003-07
Breeding confirmed109
Breeding probableexcluded from totalexcluded from total
Breeding possibleexcluded from totalexcluded from total
No of tetrads occupied10 (of 478)9 (of 490)
Percentage of tetrads2.1%1.8%

Grey herons generally nest in mature trees, deciduous tree species such as oak and beech together with conifers such as Scots pine. Cliff-nesting Grey Herons have been recorded on parts of the St. Brides Bay coast in the 1960’s and 70’s, there have even been instances of ground-nesting (Donovan & Rees, 1994).

Between the 1984-88 and 2003-07 surveys, there have been changes in the distribution and numbers of heronries in the county. The number of tetrads where breeding was confirmed dropped from 10 to 8.  The data obtained from the BTO heronries census show that between the two surveys, at least one established heronry was lost, Shipping Wood, which was clear-felled in the late 1990s, and the oldest continuously occupied heronry in the county at Slebech fell into disuse in 1995/96 when the birds relocted to another site on the Western Cleddau. 

The heronries census also includes records of single nests in several parts of the county, though these tend to be occupied only sporadically.  Such sites were recorded at Templeton, Westfield Pill, Bosherston Lily Ponds and Crygmarren Pool during the 2003-07 survey.

It can be difficult to locate nest sites and to confirm the breeding status of Grey Herons, especially once the leaves have come out on deciduous trees, or in dense conifer plantations where access can be difficult.  This could explain the relatively high number of possible breeding records (not included on the maps), especially if these involved pairs nesting singly away from the established colonies.  Total numbers of breeding pairs vary from year to year, and it is difficult to accurately estimate the size of the breeding population. 

In 2007, the five heronries that were counted as part of the heronries census yielded a total of 35 pairs.  In the mid-1990s the number of pairs regularly exceeded 40 and peaked at 60 in 1997. The total breeding population could therefore be somewhere between 40 and 70 pairs. Donovan & Rees (1994) quote a range of between 30 pairs when the population is at a low ebb, e.g. following the harsh winter of 1962-63 and 65 pairs in more favourable times.

Jane Hodges

Records extracted from the Pembrokeshire Bird Reports, which may contain more detail than shown here.

More about the Grey Heron in Pembrokeshire

Grey Heron – 1994

Ardea cinerea – CREYR GLAS – Breeding resident.

1984-88
Breeding confirmed10
Breeding probableexcluded from total
Breeding possibleexcluded from total
No of tetrads occupied10 (of 478)
Percentage of tetrads2.1%

Heronry sites have shifted widely during recorded times, that at Slebech Park being the only one that has been consistently occupied since Mathew (1894). Total numbers vary, with very cold winters causing increased mortality when ice renders prey inaccessible. The breeding population varies between about 30 pairs when at a low ebb (e.g. in 1962) and 65 pairs in more favourable times (e.g. in 1974). However, some colonies declined in the late 1980s despite mild winters and against the national trend. Single pairs occasionally nest away from established colonies and can then be easily overlooked. Colonies vary between five and twenty nests. That at Slebech has contained as many as 46 nests but has decreased in recent years (see graph).

Herons formerly bred on the cliffs in the Solva—Newgale—Nolton areas of St Bride’s Bay and at Linney Head, but this has not been recorded since 1974. A pair nested on the ground at Trefeiddan in 1978.

Grey Herons feed widely across the county, from the outer coast to the smallest inland pool, even exploiting the upper slopes of the Preseli Mountains at frog-spawning time. They disperse widely in the autumn, birds reaching all the offshore islands and on several occasions, small parties of juveniles have been seen flying due west out to sea.

Donovan J.W. & Rees G.H, 1994, Birds of Pembrokeshire

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Grey Heron – 1980s winter

Ardea cinerea – CREYR GLAS – Breeding resident.

The BTO winter atlas showed that Grey Herons were present in most 10km squares of their known breeding range during the winters of 1981-82, 1982-82 and 1983-84, being equally at home by fresh and salt waters.

The darker the colour, the higher the relative total count for each 10km square.  The darkest blue represents over 7 birds.

Data collected by volunteers for the BTO. Lack, P. 1986 Atlas of wintering birds in Britain and Ireland. T & A.D. Poyser.

More about the Grey Heron in Pembrokeshire

Common Heron – 1949

Ardea cinerea cinerea

Mathew mentions heronries at Sealyham, Pointz Castle (dispossessed by Cormorants), Slebech (believed colonies from last) and Linney Head. 

Within the last ten years heronries have been recorded only at the following sites: Llwyngwair (nine nests in 1940, felling destroyed this heronry; in 1948 only four pairs nesting in adjacent wood); Slebech (twelve, 1939, moved to Picton, six nests in 1947); and on cliffs Nolton (three 1939), Solva (one 1940), Pointz Castle (two 1946), Poth Liskey (one, 1928), Ramsey (one 1931, 1932, 1946 and 1948), Goodwick (two 1947), and Fernhill (one 1947).

R.M.Lockley, G.C.S.Ingram, H.M.Salmon, 1949, The Birds of Pembrokeshire, The West Wales Field Society

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Grey Heron – 1894

Ardea cinerea – A common resident.

Although there are no large Heronries in the county, there are numerous small breeding stations, and the bird is generally distributed and fairly common. Our fishponds at Stone Hall were constantly visited by Herons that came from Sealyham, where there are a few nests in one of the covers. We have counted seven together of a summer’s evening by one of our ponds, and we never went down to the Cleddy at any day in the year without seeing one or two, and after a long-continued drought in the summer, the birds would be especially numerous, as they then had better opportunities for capturing the eels, small trout, &c, that form their prey.

Herons suffer severely after a long-continued spell of frost, when we have come across them perfectly starving. We captured one once, and brought him home, and put him in our carriage house, where he preferred to perch upon a high dog-cart. Here we fed him for about a fortnight, until we thought he had almost become strong enough to be restored to liberty, but one morning were vexed to find him lying dead upon the ground.

We have often seen Herons perched upon the oak trees bordering one of our ponds. Here they would sit for some time before they descended to the shallow end of the pond in search of frogs and small fish or water-rats, and we believe they are expert catchers and devourers of these rodents. Some Herons nest upon the cliffs of the coast; we have already related how those at Poyntz Castle were dispossessed by Cormorants. The ejected Herons are stated to have migrated to Slebech, where they have formed a heronry. There is a heronry at Llanmilo, near Pendine, just over the borders of the county in Carmarthenshire, which, we are informed, consists of about thirty nests.

Mr. Tracy mentions another at Linney Head, where the Herons nest in company with Cormorants and Guillemots. The nests, from six to twelve in number, are arranged side by side on the ledges of the rocks, and are quite inaccessible.

Mathew M.A. 1894, Birds of Pembrokeshire and its Islands

More about the Grey Heron in Pembrokeshire

Grey Heron

Ardea cinerea – CREYR GLAS – Breeding resident.

Grey Heron – Winter 2021

Winter distribution map, and the latest figures from the Wetland Bird Survey in Pembrokeshire – totals from all count sites.

Grey Heron – 2003-07 breeding

Ardea cinerea – CREYR GLAS – Breeding resident. Comparison with previous atlas: 1984-88 2003-07 Breeding confirmed 10 9 Breeding probable excluded from total excluded from total Breeding possible excluded from total excluded from total No of tetrads occupied 10 (of 478) 9 (of 490) Percentage of tetrads 2.1% 1.8% Grey herons generally nest in mature trees, […]

Grey Heron – 1994

Ardea cinerea – CREYR GLAS – Breeding resident. 1984-88 Breeding confirmed 10 Breeding probable excluded from total Breeding possible excluded from total No of tetrads occupied 10 (of 478) Percentage of tetrads 2.1% Heronry sites have shifted widely during recorded times, that at Slebech Park being the only one that has been consistently occupied since […]

Grey Heron – 1980s winter

Ardea cinerea – CREYR GLAS – Breeding resident. The BTO winter atlas showed that Grey Herons were present in most 10km squares of their known breeding range during the winters of 1981-82, 1982-82 and 1983-84, being equally at home by fresh and salt waters. The darker the colour, the higher the relative total count for each 10km […]

Grey Heron – 1968-72 breeding

Ardea cinerea Red = breeding confirmed Orange = breeding probable Yellow = breeding possible More about the Grey Heron in Pembrokeshire

Common Heron – 1949

Species account from the Birds of Pembrokeshire, 1949, by Lockley, Ingram and Salmon.

Grey Heron – 1894

Species account from the 1894 ‘Birds of Pembrokeshire and its Islands’ by Rev M A Mathew