Rookery survey progress

This map shows the progress we are making in Pembrokeshire with the all Wales Rookery Survey 2022-23.

For a list of known rookeries (from previous surveys) see here

Results to 30th April 2022

This map will be updated every few days, so please enter your records (positive or negative) as soon as possible.

Hatched square = priority tetrad, no rookeries found

Grey square = priority tetrad, rookeries found

Red dots = Rookeries counted

Black dots = Rookeries checked but nothing there now.


Please enter your records (even if it is a zero count at a previously known site). If you enter a zero count, don’t forget to click on the button that asks if it is a negative record. I see that some sites on the map are showing as a counted rookery (in red) when actually there was nothing there – but the negative record button wasn’t used.

Records can be edited later if you do a recount and find more nests there – if you counted a rookery in March or early April, it may be worth having another look now – before there are too many leaves on the trees.

Download Instructions for entering records here.


Finding tetrads in a 10km square

Casual records can be entered using a GPS reference or picking the place on the map/aerial photo. You can do a more intensive search by tetrad 2km x 2km square. Here is how to find a tetrad:

A 10km square is normally divided into 100 1km squares, Some surveys, such as this one, is based on tetrads – 2km x 2km squares. Within each 10km square, the tetrads are given a letter as shown in figure 3.

More about the Rook in Pembrokeshire

A list of known rookeries in Pembrokeshire

These tables are to help you find rookeries to count for the 2022-23 survey.

For this survey, you can register to do a full survey of priority tetrads, and/or submit casual records of rookeries from anywhere.

If you visit any of the sites listed in the tables below, and do not find any rooks nesting, please still enter the data as a zero count, so that we know it has been checked. There are likely to be plenty of rookeries that we do not know about, and some rookeries that will move to a new group of trees.

These tables have been compiled from various sources including bird reports, breeding bird atlas data, detailed local studies, BirdTrack, etc. There was no standardised method of data collection for historical records, so it is impossible to eliminate all inconsistencies.

Where a count is given in the tables below, it is the highest count of nests in that decade.

A zero count means there were definitely no nests seen (although we don’t necessarily know exactly when the last occupation was). Note that in 1996 there was a national survey in which random tetrads were surveyed, some of which had zero counts but no known earlier records. A blank means there is no data – probably because the site wasn’t recorded in that decade.

Where there is a named rookery in a tetrad, that does not mean it is the only rookery there. Where the tetrad reference appears in the place name column, that is the only information available.

The same rookery may have been given different names by different observers.

Where a particular named rookery appears in more than one tetrad, it may be that:

  • it is located on the border
  • the rooks have moved across the border to a different clump of trees
  • the nests are sufficiently spread out that it really does cross the border (the rooks aren’t reading the maps first!)
  • the surveyor estimated the grid reference incorrectly (especially in the days before GPS and aerial photos)
  • different surveyors estimated the grid refs differently
  • For some sites, we have only a place name, and the grid reference from that
  • The nearest place name is not necessarily in the same tetrad as the rookery
  • A detailed local survey (eg at St Davids) may divide a single rookery into smaller pockets of activity

Do not worry about these inconsistencies. These tables are purely to help you find rookeries to count for the present survey. We may be able to iron out a few more of these inconsistencies in the future.

We can provide extra details about tetrads with named rookeries – email here – giving the tetrad name or the 10km sq, or your postcode, so we know what area you are interested in.

Please enter your records (even if it is a zero count at a previous site)

Download Instructions for entering records here

More about the Rook in Pembrokeshire

Rook – 2013-14 rookeries survey

Corvus frugilegus – YDFRABreeding resident

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 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 1980s and 1990s 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 (note that no attempt was made to locate and count all rookeries)

Bob Haycock (BTO rep & Chairman of the Pembs Bird Group)

More about the Rook in Pembrokeshire

Rook – 2003-07 breeding

Corvus frugilegus – YDFRABreeding resident

Comparison with previous atlas:

1984-882003-07
Breeding confirmed220211
Breeding probable33
Breeding possibleexcluded from totalexcluded from total
No of tetrads occupied223 (of 478)214 (of 490)
Percentage of tetrads46.7%43.7%

The Rook looks similar to a Carrion Crow but has a stepped forehead, a pointed bill, a grey–white area of bare skin around the base of the bill and loose flank feathers giving it a “baggy trousers” appearance. The large nest built of sticks is placed in the crown of a tree and several nests are grouped close to each other so that a colony is formed.

There have been many small shifts in the sites of rookeries in the county but no great change in overall distribution. Note the “Possible breeding” category has been omitted when assessing distribution, as Rooks recorded feeding in fields do not give any indication of the origin of their rookery. Site relocations have mostly been due to tree felling but in some cases are for unknown reasons. No complete county rookery census has been conducted during the last 30 years. 

Based on the three previous censuses a county population of between 8,000 and 10,000 pairs was extant over a period of 31 years. The BBS has indicated a 15% decrease in Wales between 1994 and 2007. However 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. On the information available, it seems reasonable to conclude that there has been no marked change in the Pembrokeshire breeding population and that a countywide census is desirable.

Graham Rees. Pembrokeshire County Bird Recorder 1981-2007

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

More about the Rook in Pembrokeshire

Rook – 1994

Corvus frugilegus – YDFRABreeding resident

1984-88
Breeding confirmed220
Breeding probable3
Breeding possibleexcluded from total
No of tetrads occupied223 (of 478)
Percentage of tetrads46.7%

Resident and abundant in all districts according to Mathew (1894), who noted that thousands perished in the severe winter of 1880. Lockley et al. (1949) also knew the Rook as resident and numerous.

They now nest throughout Pembrokeshire wherever there are suitable trees amid farmland, and are only absent from the mountain tops and the offshore islands, though they occasionally visit Ramsey and to a lesser extent Skokholm and Skomer.

The BTO census of 1944-1946 located a total of 9,664 nests in 147 colonies in Pembrokeshire. The Dyfed Wildlife Trust conducted a repeat survey in 1971 and found 10,109 nests in 281 rookeries. The BTO census of 1975-1976 logged 8,280 nests in 268 colonies. It would seem therefore that the Pembrokeshire population has been fairly stable for a long period; a sample census conducted by T.C.E. Hughes in 1986-1993 reached the same conclusion.

Saunders (1975) noted that the average rookery size had decreased between the 1944-1946 survey and that of 1971. He also noted that rookeries were sparse in the east of the county. The Breeding Birds Survey of 1984-1988 found that many areas in the east had since been colonised.

Lockley (1947) noted a regular south-west to north-east movement off the sea during March and early April. McCanch (1985) noted large scale departures to the west and north-west over the South Bishop during November 1975, including 350 on 6 November and 110 on 8 November. No other marked movements have been noted.

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

LOCKLEY, R.M. 1957. Pembrokeshire. London, Robert Hale

McCANCH, N. 1985. A lighthouse notebook. London, Michael Joseph.

SAUNDERS, D.R. 1975. A Pembrokeshire Rook survey 1971. Nature in Wales 14: 190-195.

More about the Rook in Pembrokeshire

Rook – some historical notes

Corvus frugilegus – YDFRABreeding resident

Bertram Lloyd: visited a number of colonies between 1928 and 1938. Mostly he classified them as small or large, and occasionally provided nest counts.

1928: A widespread colony stretching to the trees on the edge above the Nevern River, at Berry Hill. It is the biggest in this rook-rich county, I think.

1934: one of the biggest in the county I guess is at Berry Hill Farm, Newport. 100 is perhaps a low estimate.

From Pembrokeshire Birds Archive


ROOKS IN WEST WALES IN 1955

A rookery in St. Ishmaels, Pembs., where there were 94 nests on 3rd April was completely deserted by May 16th. I have since heard that it was raided by boys, but they could scarcely have robbed every nest. In 1953, the rookery had 124 nests, the most it has ever had and there were 120 in 1954. The average for the past seven seasons is 104 nests. Some young were reared in a rookery about half a mile from this one, but my informant did not notice whether or not the number that fledged was normal. A little more than a mile from these there was a small rookery of 15 nests in 1954, but it was not occupied this year.

The breeding failure of the Rooks that nested near my home caused me to look out for young ones foraging in the fields, but I saw none, and others in the district noticed their scarcity.  Lifting of the potatoes in a field near my house began on 20th June, and I saw upwards of a dozen Rooks there every morning, and on 25th June I counted thirty-three, but I saw no juveniles. The Jackdaws with them were both adults and young.

I am indebted to J. A. Phillips, the County Pests Officer, for the following note on the general decline in the population in Pembrokeshire:  “There is evidence that Rooks are fewer this year. We find that out of a total of over 150 rookeries in the county (censused a few years ago) some have disappeared completely whilst others are much reduced in size … At Cottesmore where there used to be a very large rookery; General Massy tells me that hardly any were hatched, and the number of nests was the lowest ever …. My foreman reports a Buzzard attacking a young Rook on grassland, and quickly killing and eating the bird.”

I have been told of young Rook plucks attributed to Buzzards on hay cocks in a field in Marloes. A neighbour noticed two Rooks’ nests, and young birds just out of the nest, at Mullock Bridge on 26th June. The nearest rookery is the one that failed completely this year, about three-quarters of a mile away. Rooks have not bred at this site before. H. R. H. Vaughan finds a remarkable reduction in Rooks in the upper Towy Valley around Rhandirmwyn, Carms.

T. A. W. DAVIES Nature in Wales 1: No 3 p141-2


A Pembrokeshire Rook Survey 1971

In 1971 281 rookeries were located in Pembrokeshire containing a total of 10 109 nests. The average size of Pembrokeshire rookeries in that year was 36 nests, ranging from several sites with only a single nest to the largest, that at Llanychaer Court SM990358 with 265 nests. Half of the rookeries contained less than 25 nests while only 21 were encountered with more than 100. As seen in Table 1 most of the Pembrokeshire Rooks nest in small colonies, even our largest rookery being of a modest size when compared to some elsewhere in Great Britain.

David Saunders. full report – Nature in Wales, Vol 14. No3, March 1975


Nevern Church rookery – Margaret Patterson

1986: On the boundary of SN0840 & SN0838. This, at first rook count (Atlas), nests were all crowded in a cluster of Scots Pine by Nevern Church Hall. These trees are dying. Some rooks moved across the road to lime trees. Now the last 2 cold late springs have killed off the tops of these trees, and some rooks have spread to 1) an oak by the old school, 2) two tall conifers (one Scots Pine and one spruce) at the east end of the old churchyard, so the rookery now spreads to 4 groups of trees. There is another rookery about 1/4 mile east.

From Pembrokeshire Birds Archive


Rising Sun rookery (Pelcomb Bridge) – GC & KJ Thomas

1987: No sign of a rookery when present occupiers moved in – 1984, but nests increasing annually afterwards. High winds of autumn 1987 cleared all nest remains so that new building would be necessary in 1988. The first nest was observed on 17 Feb. By 6 May a count of 50 nests was obtained by ‘walk about’ as by this time rookery had extended to trees on the opposite side of the road. In view of increased foliage by this date, the number of nests could have been 60+.

From Pembrokeshire Birds Archive


David Little and David Levell have been counting rookeries in south Pembrokeshire every ten years since 1986. The results are written-up here


References:

DAVIES T.A.W. Rooks in West Wales in 1955, Nature in Wales Volume 1, No 3, p141-2

LITTLE D,.I LITTLE A.E, & LEVELL D 2001, A review of Rook status, with new south Pembrokeshire data, 1986-96. Field Studies 10, 37-56. Field Studies Council.

REES G.H. Pembrokeshire Birds Archive

SAUNDERS, D.R. 1975. A Pembrokeshire Rook survey 1971. Nature in Wales 14: 190-195

More about the Rook in Pembrokeshire

Rook – 1980s winter

Corvus frugilegus – YDFRABreeding resident

The BTO winter atlas showed that Rooks were present in most 10km squares during the winters of 1981-82, 1982-82 and 1983-84.

The darker the colour, the higher the relative total count for each 10km square.  The darkest blue represents over 800 birds seen in a day.

Use of treeless coastal areas resulted in a winter distribution that was slightly more extensive than the breeding range.

Graham Rees. Pembrokeshire County Bird Recorder 1981-2007

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 Rook in Pembrokeshire

Rook – 1945 rookeries census

Corvus frugilegus – YDFRABreeding resident

Between 1944 and 1946 as part of a wartime investigation into the economic importance of the Rook, rookeries in many parts of England, Scotland and Wales were censused. This work was undertaken by the British Trust for Ornithology following a request from the Agricultural Research Council. The enquiry was organised by the late James Fisher and over 600 observers contributed information. This has never been published and is now deposited with the B.T.O. at Beech Grove, Tring, Hertfordshire.

Pembrokeshire was one of the better-covered of the Welsh counties, its rookeries being counted in the spring of 1945 by N. B. Davies. J. T. Daye, J. W. Lavis, J. O. Richards and M. R. Warlow. Some 147 rookeries were located containing a total of 9,644 nests.

This map (probably produced by Graham Rees) shows that rookeries were found in 108 tetrads.


References

SAUNDERS, D.R. 1975. A Pembrokeshire Rook survey 1971. Nature in Wales 14: 190-195

REES, G.H. Pembrokeshire Bird Archive

More about the Rook in Pembrokeshire