Rookeries survey 2013/2014

In 2011/12 it was commented on by several observers that some rookeries had either disappeared, or declined considerably in parts of Pembrokeshire.  In 2013 and 2014 birdwatchers were asked to count the nests in any rookeries they came across in the county.  No attempt was made to find all rookeries, or to visit all tetrads where rookeries had previously been recorded.

A minimum of 3,776 apparently occupied rook nests was recorded in 2013/14 from 138 rookeries surveyed. The largest rookery (at Dale) contained 178 apparently occupied nests (AON). The average rookery size was 27 AON.

Rookeries were recorded within 110 tetrads, which represented about 50% of the tetrads where rookeries were found during the 2003-07 Pembrokeshire breeding birds atlas survey (Rees et al. 2009). During the 2013/14 survey, rookeries were recorded from an additional nine tetrads where there was no evidence of breeding reported during the 2003-07 atlas survey period. However, all bar one of these had previously been confirmed to have breeding rooks in the first Pembrokeshire breeding atlas survey (1984-88) (Donovan & Rees, 1994).

At least fourteen rookeries were found to have 'disappeared'. These had ranged in size from 9 to 102 AON in a census of south Pembrokeshire rookeries undertaken in 1996 (Little and Level 1996). No alternative sites were found in the vicinity of these rookeries in 2013/14, although there was anecdotal evidence of two of them having attempted to relocate in the five years subsequent to their last being occupied.

If the population of 3,776 AON, from about 50% of the tetrads with confirmed breeding rooks in 2003-07, is a typical of the population across the remaining 50% of un-surveyed tetrads in 2013/14, then a total county population of at least 7,550 AON is possible. This assumes that the average rookery size in the un-recorded parts (e.g. in the northeast) is similar to that for the surveyed rookeries in the remainder of the county.  

Data from three previous censuses of the rook population (a BTO census of 1944-46, a Dyfed Wildlife Trust census of 1971 and a BTO census of 1975/76) suggested a population of between 8,000 and 10,000 pairs. Limited local surveys conducted over a period of 15 years in the 1980’s and 1990’s showed fluctuations in annual totals but stability overall. It was suggested that the population was still likely to be in this range in 2003-07 (Rees et al. 2009). Data from the 2013/2014 survey suggests a population closer to the lower estimate.

Orange squares show tetrads where rookeries were recorded in the 2003-07 atlas

Black circles show rookeries counted in 2013-14

Yellowhammer - breeding atlas change map

Orange = distribution in 1984-88 survey

Large dots = confirmed breeding 2003-07

Medium dots = probable breeding 2003-07

Small dots = possible breeding 2003-07

Percentage change = 50% reduction

Red-breasted Merganser - Breeding records

1995 - Female noted at the Gann 18 June.  Reappeared on 6-7 July with 2 large flightless young (GHR et al), the first breeding recorded in Pembs. 

2005 - Female with 4 ducklings Eastern Cleddau, 24 June

Records from Pembrokeshire Bird Reports for those years.

Grey Heron - 2017 and 2018 Heronry census counts

A total of 42 nests counted from six heronries counted in 2017.

A total of 39 nests counted from eight heronries surveyed for the national heronries census in 2018 (the 90th anniversary year of the national census). 

Heronry                       No. of nests in 2018         No. of nests in 2017

Bosherston Lakes                    2                                     2

Westfield Pill                         12                                   13

Upton (Carew River)               1                                      2

Eastwood (Millin Pill)               3                                  N/C

Sealyham (Afon Anghof)         4                                      5

Priskilly (Western Cleddau)      4                                     8

Felindre Farchog (Afon Nyfer)  4                                  N/C

Cwm Cych (Afon Cych)            9                                   12

Little Grebe - breeding

 Tachybaptus ruficollis

Breeding resident and winter visitor.

The Little Grebe breeds throughout the temperate and tropical Old World and is resident, dispersive and migratory.

In Pembrokeshire it inhabits still fresh waters in the breeding season so is absent from the fast flowing rivers and streams. It requires waters to be vegetated around the fringes and beneath the surface. It is secretive and inconspicuous around the breeding area and can easily be overlooked, its far carrying, distinctive, whinnying call often being the first indication of its presence.

The breeding status of this species in the county in the past is difficult to evaluate. To Mathew (1894) it was a breeding species but by 1949 Lockley et al stated “apparently does not breed”.

Saunders (1976) commented “Strangely it does not remain to breed, for at least to human eyes, there are several suitable waters.”

However, Bertram Lloyd’s diaries contain records of breeding at Llambed in 1936 and suspected breeding at Slebech in 1937 and Sharrock (1976) indicated possible breeding between 1968 and 1972 in the south west of the county.

Donovan and Rees (1994) quoted breeding at Thornton Reservoir (now defunct) in 1965, at Pembroke Mill Pond in 1975 and at Trefloyne in 1981, with suspected breeding at Bosherston during the 1970’s and 1980’s.

The lack of breeding during the review periods of Lockley et al and Saunders might well have been the result of severe winters in 1939-40, 1947-48 and 1962-63 eliminating a small population which was previously present.

Two breeding bird surveys of the county using a grid of tetrads have since been completed and the results are summarised as follows: 

[Breeding maps & statistics]

Comparison of the results of the two surveys indicates an almost fourfold increase in the number of occupied tetrads during the elapsed period. Most birds were on well vegetated farm ponds used for irrigation. Many of the ponds used in 2003 – 07 had only recently been constructed in the 1980’s and only subsequently became vegetated and thus suitable for Little Grebes.

Although most small waters were used by just one breeding pair, some tetrads encompassed more than one such body of water and on some larger waters there was more than one pair, for instance there were four pairs at Marloes Mere. Allowing for these variables, the county total was estimated to be about 70 pairs by 2007, compared to 12 pairs in 1988.

Graham Rees

(Covers records up to and including 2008)

References

DONOVAN. J and REES. G. 1994. Birds of Pembrokeshire, Dyfed Wildlife Trust.

LLOYD. B. 1929-1939 Diaries, National Museum of Wales.

LOCKLEY. R. M, INGRAM. C. S. and SALMON. H. M.1949. The birds of Pembrokeshire, West Wales Field Society.

MATHEW. M. 1894. The birds of Pembrokeshire and its islands, R. H. Porter.

SAUNDERS. D. R. 1976. A brief guide to the birds of Pembrokeshire, Five Arches Press.

SHARROCK. J.T. R. 1976. The atlas of breeding birds in Britain and Ireland, Berkhamsted, T. & A. D. Poyser.

Carrion Crow - 2010

Corvus corone

Breeding resident.

The Carrion Crow was assessed as common and widespread in Pembrokeshire by Mathew (1894), Lockley et al (1949) and Donovan and Rees (1994). They were persecuted by gamekeepers during Mathew’s time, a hint of the scale being the record of 134 killed on the Cawdor estate in 1821. This continued into the Lockley et al era, an example being 150 counted on a gibbet at Slebech in 1930. Such carnage diminished during the two World Wars when many gamekeepers were recruited to the armed services. Control measures are still attempted but on a small and localised scale, so they are now unmolested over much of their county range.   

Nesting in trees, on old buildings and cliff ledges, the Carrion Crow has been found breeding all over the county, including the major offshore islands. Its breeding distribution was plotted in 1984 – 88 by a survey using tetrads as a grid and this was repeated in 2003 – 07.

Breeding surveys	1984 – 88	2003 – 07
Total tetrads where found	459	453
Confirmed breeding	390	354
Probable breeding	22	51
Possible breeding	47	48

An estimate of the breeding population was attempted following the survey of 1984 – 88, which was based on the distances between nests in a small number of random localities. With no other information available at the time, this was used to calculate a county total breeding population of 18,000 – 21,000 pairs. With the benefit of hindsight this is now considered to be an inflated total. The BTO’s New Atlas of 1988 – 91 showed Pembrokeshire contained Carrion Crows at maximum abundance and if their UK average density is used as an adjustment, a county population of about 10,000 pairs results, which seems more realistic. The 2003 – 07 survey found no marked difference in distribution from the 1984 – 88 survey, so there was probably no change in the size of the breeding population.

Being a successful breeder the Carrion Crow produces a surplus component to its population, comprised of immature birds that are too young to breed or adults which cannot find a vacant breeding territory. In places these form flocks which have been most noticeable on parts of the estuaries such as Fowborough and the Gann. This “reservoir” enables territories made vacant by various means, like shooting, to be recolonised.

There are several records of Carrion Crows flying in off or out to sea at headlands and islands, as far out as The Smalls, but the only concrete evidence of migration was of a nestling ringed on Bardsey Island which was recovered in north Pembrokeshire. 

Graham Rees.

(Covers records up to and including 2010)

Eider - breeding

Somateria mollissima

Breeding was suspected at Caldey in 1981 and a flightless group in the St Govan’s Head/Barafundle   area in July 1983 was thought to be a female with a brood of large young.

Great Crested Grebe - breeding

Podiceps cristatus

Few fresh water sites in Pembrokeshire are suitable for Great Crested Grebes. One was seen at Bicton Reservoir in November 1980 and ones and twos occurred sporadically at Bosherston between 1984 and 1997.

One was at Heathfield Gravel Pit on 27th May 1999, with two there on 4th July 2001 and breeding was attempted in 2005 but was unsuccessful.

From one to five were seen at Llys y fran Reservoir in most years between 1985 and 1995, then in 1996 a pair bred but the nest was predated at the egg stage. Birds were present in the following years but breeding was not proven again until 2004. A pair present with three juveniles in July 2002 was suggestive but at that date could have come from elsewhere.

A single bird was seen at Rosebush Reservoir on 20th September1992, where a pair built a nest in 1995 but did not breed. A pair hatched a chick in 1997, were seen sitting on a nest in 1999 and 2002 and bred in 2004, 2005 and 2006.

A bird of the year was picked up unharmed in Haroldston Hall farmyard on 27th July 1966, it was released onto the farm’s irrigation reservoir where it spent several days before leaving.

Graham Rees

(Covers records up to and including 2006)

Common Sandpiper - 1894

Species account from M Mathew, 1894, "The Birds of Pembrokeshire and its islands"

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Mute Swan - 1894

Species account from M Mathew, 1894, "The Birds of Pembrokeshire and its islands"

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Wren - 1894

Species account from M Mathew, 1894, "The Birds of Pembrokeshire and its islands"

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Marsh Tit - 1894

Species account from M Mathew, 1894, "The Birds of Pembrokeshire and its islands"

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