Cormorant – 2003-07 breeding

Phalocrocorax carbo – MULFRANBreeding resident

Comparison with previous atlas:

Breeding confirmed1313
Breeding probable12
Breeding possibleexcluded from totalexcluded from total
No of tetrads occupied14 (of 478)15 (of 490)
Percentage of tetrads2.9%3.1%

The largest colony of Cormorants is on St Margaret’s Island and this is one of the best studied in the UK, with almost continuous census data for 50 years and over 5,000 chicks ringed since the mid 1960’s.  There are  smaller colonies on Thorne Island (it relocated from Sheep Island in the early 1990’s), on the Mew Stone, Skomer, at times on Stack Rocks off Little Haven, on the Green Scar at Solva, around Dinas Island and at Cemaes Head.  Occasionally pairs might nest at scattered mainland sites.  There are many coastal drying out sites (including jetties etc in the Milford Haven Waterway) where sometimes good numbers of birds can be seen.

The Cormorant population fluctuates from year to year, as probably in poor springs some birds fail to breed. Overall counts show there was a tendency to a decrease during the 1990’s but a modest increase again in the early 2000’s.  The total population in the county in 1984-88 survey was around 300 pairs and a census following the Sea Empress oil spill (1996) found 360 pairs, with 180 of these on St Margaret’s Island.  The population during the most recent years appears to have been stable and may have increased slightly.

The highest county population was almost certainly in the early 1970’s, when around 450 – 500 pairs probably bred, 330 of them on St Margaret’s, but the reasons for the subsequent decrease are poorly understood.  Breeding success varies from year to year but there are few years of substantial failure. Ringing has shown that considerable numbers are shot on rivers or killed in coastal fishing nets during the winter period. It seems likely that this is a major cause of population changes.

Steve Sutcliffe

More about the Cormorant in Pembrokeshire

Gannet – 2003-07 breeding

Morus bassana – HUGAN – Breeding resident.

Comparison with previous atlas:

Breeding confirmed12
Breeding probable
Breeding possible
No of tetrads occupied (of 478) (of 490)
Percentage of tetrads0.2%0.3%

Despite being relatively widespread around the coast, gannets are confined to breeding on just one small remote island, Grassholm – about 12 miles off the Pembrokeshire mainland. Here they nest at very high density, the only breeding colony for this species in Wales. Because of the importance of the Gannet population on Grassholm (in European and indeed World terms) the island has been designated a Special Protection Area for them (under the EC Directive on the conservation of wild birds (79/409/EEC).  

Counting the population is a special operation requiring skilled observers. The colony is now so dense that visitors are no longer able to land on the island as this causes too much disturbance. Because of this, assessments of the colony population size have to be made from aerial surveys usually done in late summer. This is done by counting the number of apparently occupied nest sites (AOS) observed in photographs. This process is now considerably aided by modern high quality digital photographic equipment and computer mapping software.

The most recent aerial survey during the 2003-07 atlas period was undertaken in July 2004 by ornithologists from the Centre for Ecology and Hydrology with a follow up ground survey (after the young had fledged) in September the same year to confirm the colony boundary areas. (Wanless et al 2005).

During the 1984-88 atlas period, the population estimate was 28,600 AOS in 1984–85, with an estimated 30,000 AOS in 1986 (Lloyd et al. (1991).

By 1999, the population was an estimated 30,688 AOS. In 2004 the population had risen to 32,094 AOS; an increase in colony size between 1999 and 2004 of 4.6% (a rate of approx 0.7% per annum). Comparison with other UK and Irish Gannet colonies in 2004 indicated that Grassholm is the third largest northern Gannet colony in Britain, supporting approximately 12% of the UK and Irish population, about 8% of the World population (Wanless, et al, 2005).

If the well documented population expansion and gradual spread of the colony across Grassholm continues, it is interesting to speculate where a new Gannet colony may form if they eventually run out of space! For a few years, (during the 2003-07 atlas recording period) one Gannet appeared to be resident on St Margaret’s Island each summer, making a nest and even laying an egg in one year. However, no mate was ever confirmed and successful breeding did not occur, so Grassholm currently retains its status as the only Gannet colony in Pembrokeshire and in Wales.  

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

LLOYD. C, TASKER. M. L and PARTRIDGE. K. 1991.The status of Seabirds in Britain and Ireland, T & A D Poyser, London

WANLESS. S, MURRAY. S, HARRIS. M.P. and EVANS. S, 2005. A count of the Grassholm Gannetry in 2004. CCW Contract Science Report No. 604.

Update: Since the atlas fieldwork period was completed, another aerial survey was undertaken in 2009. This survey produced a mean population estimate of 39,292 AOS. Between 2004 and 2009 numbers of Gannets on Grassholm had therefore increased by 22.4%, at a mean rate of 4.1% pa. Grassholm remains the third largest gannetry in the UK; by 2009 holding approximately 15% of the UK and Irish population and 9.5% of the world population. Murray (2009).

MURRAY. S. 2009. A count of the Grassholm Gannetry in 2009. Contract Report to RSPB/CCW

More about the Gannet in Pembrokeshire

Shag – 2003-07 breeding

Phalacrocorax aristotelis – MULFRAN WERDD – Breeding resident and passage migrant

Comparison with previous atlas:

Breeding confirmed2827
Breeding probable43
Breeding possibleexcluded from totalexcluded from total
No of tetrads occupied32 (of 478)30 (of 490)
Percentage of tetrads6.7%6.1%

Shags are essentially inshore feeding birds that prefer rocky coastlines.  Their nests are well-distributed around Pembrokeshire, with concentrations on the offshore islands. 

Despite being relatively common around the coastline, breeding Shags are not very easy to count accurately because they nest in deep crevices and so can be almost invisible.  Also some sites are not commonly visited or counted. The population has fluctuated considerably in the last fifty years with a low point during the late 1980’s and early 1990’s. The reasons for that decline are unknown but it was seen in all areas of the county. The Sea Empress oil spill in 1996 caused the death of a small number of Shags, mainly around the entrance to Milford Haven and around the south coast of the county.  The counts in 2008 were the highest since the early 1970’s and reflect high breeding success during recent years.

Only about 200 pairs currently breed in the county. The overall impression is, however, of a small but vibrant population which is doing well in the first decade of this century.

Steve Sutcliffe.

More about the Shag in Pembrokeshire

Little Egret – 2003-07

 Egretta garzetta – CREYR BACHOccasional visitor

Little Egrets were considered to be rare vagrants to Britain and Ireland until 1989 when the first of many influxes of birds into southern England occurred.  Since then, there has been a dramatic increase in numbers of Little Egrets in southern Britain, thought to be linked to the breeding success at French colonies.  The species is now very firmly established as a winter visitor to Pembrokeshire, with up to 70-80 Little Egrets over-wintering on the estuaries and open coast.

They utilise coastal lagoons, saltmarsh, brackish marsh and rocky shores as well as estuarine mud flats.  They roost communally, often sharing tree roosts with Grey Herons.  Since the mid 1990s, Little Egrets have been present in small numbers in the Milford Haven Waterway & Daugleddau Estuary during the spring and summer months (Hodges 1992-2007), and during the 2003-07 tetrad survey, breeding was finally confirmed.

Without doubt, the recent series of mild, virtually frost- and snow-free winters has been a major factor in the steady increase in the wintering population in the county, with some birds choosing to remain in Pembrokeshire to breed.  Clearly, there is suitable nesting and foraging habitat in the estuaries to support a breeding population of Little Egrets.  They are, however, extremely vulnerable to prolonged spells of cold winter weather, and their future as a breeding species in the county is inextricably linked to the severity of winters. Little Egrets are likely to gain “climate space” as a result of predicted climate change, and hence it seems likely that they will continue to become established as a breeding species in Pembrokeshire.

Jane Hodges

More about the Little Egret in Pembrokeshire

Red Kite – 2003-07 breeding

Milvus milvus – BARCUD COCH – Scarce visitor

Fieldwork 2003-07 (based on 490 tetrads)

Red = breeding confirmed, Orange = breeding probable, Yellow = breeding possible 

Tetrads in which registered = 43 (8.8%)

Red Kites became extinct as a breeding species in Pembrokeshire in the latter half of the 19th century following intense persecution. They were not recorded breeding during the last atlas survey period but they had been noted lingering in the county into the summer (Rees and Donovan, 1994). The first proven breeding attempt since then was in 2002 when a pair laid eggs near Boncath. This attempt failed but another pair fledged two chicks near the Gwaun Valley in 2003. Since then kites have gradually colonised the north-east of the county. By the end of the survey period in 2007 there were twelve pairs holding territory, at least nine of which built nests, and further expansion has been observed since then. The origins of the colonising birds are not proven but strongly suspected to be from both Carmarthenshire and Ceredigion. During 2008 two adult birds both which were known to have been born in Pembrokeshire built a nest in the north of the county.

Whilst intentional persecution of Kites is happily now a rare event, they are still susceptible to poisoning either illegally by indiscriminate baits set for foxes and corvids or accidentally from second and third generation rat poisoning. This was brought home when one of the first two nestlings to fledge in 2003 was picked up dead before leaving the vicinity of the nest site having died of rat poison.

Another Pembrokeshire-born individual became a road casualty as it stooped to pick up carrion near Welshpool, Powys, during its first winter.

However, despite these incidents, overall survival rate is high and the Red Kite is set to return as widespread and common sight in the county to be enjoyed by all.

Paddy Jenks 

More about the Red Kite in Pembrokeshire

Grey Heron – 2003-07 breeding

Ardea cinerea – CREYR GLAS – Breeding resident.

Comparison with previous atlas:

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

More about the Grey Heron in Pembrokeshire

Sparrowhawk – 2003-07 breeding

Accipiter nisus – GWALCH GLAS – Breeding resident

Comparison with previous atlas:

Breeding confirmed3723
Breeding probable3648
Breeding possible185125
No of tetrads occupied 258 (of 478)196 (of 490)
Percentage of tetrads54%40%

There has been a clear decrease (23%) in the total number of tetrads in which Sparrowhawks were recorded between the two atlas periods. There was, however, virtually no change in the combined total of confirmed and probable breeding categories with the decrease occurring only in the possible breeding category. It is also notable that despite an overall decrease there were still 74 tetrads where Sparrowhawks were recorded during the later atlas for which there were no records during the 1984-1988 fieldwork. This makes interpretation difficult. It is possible that due to their secretive nature (especially during the incubation period in May and June)  Sparrowhawks were under-recorded in both surveys.

At UK level Sparrowhawks have shown a long term increase, reaching a plateau in the early 1990’s since when they have stabilised. However, in Wales there are insufficient BBS records to obtain a reliable trend (BTO website 2009). In summary, it appears as if there may have been a decline in Pembrokeshire’s breeding Sparrowhawk population but it is difficult to be sure of its extent (if any). Perhaps targeted monitoring with better suited methods is at least worthy of consideration.

An accurate figure for the breeding population is not possible from any fieldwork carried out within the county, but assuming at least 2 pairs per tetrad in which it is recorded then a minimum of 400 pairs occur. The true figure is likely to be higher.

Paddy Jenks

More about the Sparrowhawk in Pembrokeshire

Goshawk – 2003-07

Accipiter gentilis – GWALCH MARTH – Status unclear

During the last breeding atlas, a single pair of goshawks bred in the county. Since then they have colonised, presumably from the increasing core population in our neighbouring counties. By 2007 there were between 12 and 15 pairs and they are likely to continue increasing in both number and range within the county, though perhaps always with a bias towards the better wooded east and north.

They can be very easily overlooked especially after their initial display period in February to April but they tend to be site faithful so the distribution and population estimate can be considered reliable.

Paddy Jenks

Breeding confirmed4
Breeding probable11
Breeding possible13
No of tetrads occupied (of 478)28 (of 490)
Percentage of tetrads%5.7%

Photo of juvenile goshawk at Carew Cheriton by Richard Ellis

More about the Goshawk in Pembrokeshire

Buzzard – 2003-07 breeding

Buteo buteo – BWNCATH – Breeding resident

Comparison with previous atlas:

Breeding confirmed156124
Breeding probable79167
Breeding possible170107
No of tetrads occupied405 (of 478)398 (of 490)
Percentage of tetrads84.7%81.2%

The distribution of Buzzards recorded during the two atlas survey periods is almost identical and the number of registrations 398 (405) is also very similar. Estimating the number of breeding pairs of Buzzards is fraught with problems. Many of the birds which are seen displaying and even lining a nest are non-breeding birds and studies indicate that only 25% of the population actually breed. Also a pair may frequently line more than one nest.

In their prime habitat of fairly well-wooded undulating countryside they can reach densities of up to 0.88 pairs per km2 (Sim et al 2001). Much of the east of the county can be considered to be perfect habitat, but in the more open and exposed west, breeding density is likely to be lower. If an average density is assumed of two to three pairs per tetrad over 250 tetrads in the east and one pair per tetrad over 150 in the West, then a population range of 650 to 900 pairs breed within the county, a considerable increase from the 1984-88 estimate of 250.  Increases of this order have been recorded at a UK level but the Welsh population has remained stable since 1994 (BTO website).

Given that the range has remained unchanged between the two survey periods then at least some of this increase may be explained by variation in the methods used to make the estimate.

Paddy Jenks

SIM. I. M.W, CROSS. A. V, LAMACRAFT. D. L, PAIN. D. J, 2001. Correlates of Common Buzzards, Buteo buteo, density and breeding success in the West Midlands, British Birds, Vol 95, 410 – 448.

More about the Buzzard in Pembrokeshire

Kestrel – 2003-07 breeding

Falco tinnunculus – CUDYLL COCH – Breeding resident

Comparison with previous atlas:

Breeding confirmed2621
Breeding probable3015
Breeding possible10060
No of tetrads occupied156 (of 478)96 (of 490)
Percentage of tetrads32.6%19.6%

The number of tetrads in which Kestrels were recorded, all categories, decreased from 156 to 97 between the two atlas survey periods. This 38% decline is likely to be genuine; the Kestrel is an obvious bird and is unlikely to be overlooked. The decrease has also occurred across all three categories. Using the confirmed and probable figures combined, the estimate for the breeding Kestrel population in Pembrokeshire is 30 to 35 pairs. This figure is backed up by the results of a dedicated census in 2008 which returned 31 breeding territories. A decline has also been recognised across the UK, particularly so in the southwest, and this decrease has also been accompanied by a decrease in productivity with fewer chicks fledging per nesting attempt (BTO nest record scheme).

A study in Kielder Forest, Northumberland, showed that predation by Goshawks caused a severe decline in the breeding Kestrel population (S. Petty 2003). The reasons for the decline in Pembrokeshire’s Kestrels are not known for certain but an investigation which began in 2008 showed early signs that predation of nesting adults was occurring and brood size for 10 nests was significantly lower than the national average. It is also suspected that competition for nest sites with the larger and dominant Peregrine is an issue, particularly at coastal cliff and inland quarry sites.

A nest box scheme in Pembrokeshire was initiated in 2007, in an attempt to alleviate potential nest site competition but it is too early at the time of writing to assess its effect on the Kestrel breeding population.  Given the widespread decline in the west of UK, it would seem that the Kestrel’s future is insecure in Pembrokeshire.

Paddy Jenks

More about the Kestrel in Pembrokeshire