Curlew - 2003-07

By the 1980s it was estimated that only about 20 pairs were still breeding in Pembrokeshire.  Of these, the majority (13 pairs) were on Skomer, with the rest in the boggy areas of the Preseli Hills. Between 2003 and 2007 the number of tetrads in which they were found had shrunk to just two from 12 recorded during the 1984-88 period, a decline of 83%.

They were only confirmed breeding on Skomer where six to nine pairs nested during the 2003-7 atlas period. The breeding population in Wales is also in trouble - BBS records indicate a 33% decline in the population between 1994 and 2007 across Wales as a whole, based on 37 sample sites.

Further research is needed to determine if former mainland haunts in Pembrokeshire are capable of supporting breeding curlews again.

Bob Haycock

Fieldwork 2003-07 (based on 490 tetrads)

Red = breeding confirmed = 1

Orange = breeding probable = 0

Yellow = breeding possible = 1

Total tetrads in which registered = 2 (0.4%)

Snipe - 2003-07

Within Pembrokeshire, Snipe were considered to be fairly widespread as a breeding species until about 50-60 years ago. During the 1984-88 atlas period they were recorded from nine tetrads, mainly in the Preseli Hills and in the catchment area of the Eastern Cleddau. Only a handful of pairs were recorded, and whilst breeding may have occurred in three separate tetrads, there was no certainty of this. It was thought that extensive land drainage and reduced grazing of the commons had caused the decline, with an increase in predators placing further pressure on the remaining population.

Some 20 years later, Snipe were recorded from 5 tetrads during 2003-07 but only three of these were inland within areas of potentially suitable breeding habitat. The other two locations being near the coast were almost certainly records of transient birds. Even at the inland locations, it is likely that Snipe recorded here were also migrants. No “classic” display flights were recorded and their former haunts currently seem unable to support a breeding population.

Bob Haycock

Fieldwork 2003-07 (based on 490 tetrads)

Yellow = breeding possible = 5

Total tetrads in which registered = 5 (1%)

Lapwing - 2003-07

In winter they can appear in flocks of several hundred to a few thousand and occur widely across farmland and coastal habitats. The number of pairs attempting to breed in Pembrokeshire has continued to decline over the last 20 years, continuing a trend noted in Donovan and Rees (1994).

Lapwing distribution, as indicated by the number of tetrads in which they were found, fell by a massive 86%, between 1984-88 and 2003-07, reflecting the significance of the overall decline in the breeding population. All atlas categories declined by large amounts. Breeding numbers are also declining in many other parts of Britain, and they are red-listed in the Birds of Conservation Concern 3 (Eaton et al., 2009).

The BBS index indicated a UK-wide decline of 18% between 1994 and 2007, but there were insufficient 1km squares sampled to give a Wales index for the species.  

It was estimated that there were around 70 pairs in Pembrokeshire during 1984-88. During 2003 – 2007 the maximum recorded breeding population in any one year was only 14 pairs, in 2003, with between about nine and 12 breeding pairs recorded each year subsequently, a decline of between 80 and 87%.

One or two pairs have attempted to breed on the Castlemartin peninsula, but recently the entire population has been more or less split between two key breeding centres at Ramsey Island and the old dismantled BP oil tank farm at Kilpaison. Ringing of nestlings by the Pembrokeshire Ringing Group at the latter site is showing that some young are surviving and returning in later years, possibly to breed in the same area.

Management of their breeding habitat is being carried out by the RSPB on Ramsey; this includes minimising potential disturbance from visitors to the island. Recent attempts by the RSPB to help create suitable arable conditions in the Castlemartin Corse/Broomhill Burrows area have, so far, failed to attract the birds to stay and breed successfully here.  

Bob Haycock

Fieldwork 2003-07 (based on 490 tetrads)

Red = breeding confirmed = 3

Orange = breeding probable = 0

Yellow = breeding possible = 1

Total tetrads in which registered = 4 (0.8%)

Ringed Plover - 2003-07

Within Pembrokeshire, the status of Ringed Plovers and their distribution has remained pretty well unchanged over the last c. 20 years. The table suggests a decline in the number of tetrads in which Ringed Plovers were found, but during the 1984-88 period two tetrads included birds that were most likely to have been migrants as there was no confirmed or probable breeding reported.

A single pair bred in each of the five years 2003-07 on the Castlemartin Range. The nest site is on the cliff-top above Wind Bay near Linney Head. In 2007 a second pair held territory for a short time in May and early June above Berryslade, a little way west of Wind Bay, but were not proven to have nested. Several other Ringed Plovers stayed into early June on nearby Frainslake Beach but no breeding occurred here, or in dune hollows in Brownslade Burrows where they have bred in the last decade, but outside the atlas period. The Castlemartin site was not known to be occupied in 1984, but has been in regular occupancy since around 1990.

The main nesting habitat at Castlemartin is open, exposed stony limestone terrain directly above c. 30 metre high sea cliffs, contiguous with short herb-rich and invertebrate-rich maritime grassland turf where the birds often feed. Here a small area of limestone clitter provides suitable bare ground for a nest scrape, sufficient to hide cryptically marked eggs. There are numerous boulders and crevices for chicks to hide from predators and to shelter under. Sometimes two clutches are laid over a breeding season which extends from May to August.

Despite being within a busy army training range, and with a metalled road running along-side the breeding site, the plovers are afforded reasonable levels of protection. The breeding location is identified as a “sensitive area” on estate management maps, and there is usually very little military activity close to the nest site.

Because it is an active military range, relatively few people currently visit the area, unless they are briefed and are undertaking approved activities. Guided walking groups and climbers are briefed annually about seasonal bird nesting restrictions, which covers the plover nesting zone, to minimise disturbance to cliff-nesting birds. The plovers are also monitored each year to help ensure appropriate protection measures are adequate and up to date.

Tetrads in which registered (based on 490 tetrads) = 2 (0.4%)

Bob Haycock

Oystercatcher - 2003-07

In Pembrokeshire oystercatchers are largely restricted to the coast, breeding on rocky shores, sea-cliffs and tops of small islets and larger offshore islands. On the mainland they have a fairly regular, if thinly spread, linear distribution along the coast. However, on the larger islands, Skomer and Skokholm for example, they can form loose colonies at a higher concentration.

Oystercatchers are long-lived birds and it is possible that some of the same birds observed in the 1980s were still breeding in the recent survey period.

Comparing the total number of tetrads in which they were found suggests a small and probably insignificant decline in breeding population distribution between 1984-88 and 2003-07, down by about 13%.  Although there was a large decline in the number of tetrads where confirmed breeding was reported, this was more or less balanced by the number of tetrads that registered probable and possible breeding evidence.

Scrutiny of the tetrad distribution map suggests that, although there are fewer tetrads with confirmed breeding, overall there was generally very little change in their distribution on the mainland coast and offshore islands north of Milford Haven. A close look at the map suggests that their distribution has thinned out a little along parts of the south coast.

In 1984-88, it was estimated that there were about 300 pairs of breeding Oystercatchers. At least 50% of these were on the offshore islands, where more regular monitoring is conducted. In 2003-07, the island populations again recorded in the region of 140-160 pairs. This suggests that the Pembrokeshire population is probably reasonably stable, at least in optimal habitat locations.

Monitoring of a small Oystercatcher population along the Castlemartin peninsula, between 2003 and 2007, has provided evidence of 7 – 8 regularly nesting pairs along a 20 km length of limestone coast, covering seven coastal tetrads. Nesting density was quite low and nests were patchily distributed, ranging from one – three per tetrad, but they were absent from some tetrads. Three of these pairs regularly breed at Stackpole each year in one tetrad, in some years with limited success. They are monitored annually and this number has not changed much over the last 20 years.

In 2006, it was reported that in one fairly remote nest, on the shore of Carew River, 8 eggs had been laid which was almost certainly a result of egg dumping involving two females.

Based on 76 tetrads where Oystercatchers were found along the mainland coast of Pembrokeshire, an average of two pairs per occupied tetrad would seem to be a reasonable assumption. This would suggest at least 150 pairs which, when combined with the most recent Islands totals, is similar to the 300 pairs in Pembrokeshire as a whole, estimated in the mid 1980s.

If the decline in distribution and confirmed breeding status along parts of the south coast is real and not due to observer bias, then perhaps parts of the coast are sub-optimal for this species. However, it is also worth considering other possible reasons why they could have thinned out, or their breeding success may have been affected here.

Oystercatchers breeding on the rocky coast are dependent for food on good populations of molluscs and other marine prey in the inter-tidal zone. Perhaps their apparent thinning out, and lack of confirmed breeding, along parts of the south coast is a legacy of the Sea Empress oil spill that affected this coastline in winter/spring 1996.

Surveys have shown that the coastal habitats have recovered well since, but perhaps the density and range of age structures of molluscs, limpets, whelks, mussels, and other marine prey have not yet fully recovered in some locations. Perhaps there are still insufficient food resources to fully support them throughout the breeding season?

Another possible issue that needs consideration is the increase being made of the coastal inter-tidal zone by people undertaking “coasteering”. This activity (involving combinations of rock-clambering and swimming along a linear course at the base of the cliffs, usually by groups of people) has become extremely popular along parts of the south coast and along other sections of the Pembrokeshire coastline during the last 20 years.

Whilst the routes used may not cause too much lasting damage to marine food sources in an already harsh, wave-lashed environment; breeding birds on the lower ledges and cliff-crevices may now be more frequently disturbed in areas used for recreation than was the case in the past.

The Pembrokeshire Outdoor Charter Group, involving Activity Centres and conservation bodies, are attempting to improve knowledge of the range and sensitivities of species and habitats on the coast. Hopefully this will ensure that the small number of breeding and roosting birds specialising in the harsh rocky inter-tidal zone will be afforded sympathetic protection. There is still a need to identify the areas used by wildlife and for more detailed monitoring.

Bob Haycock

Fieldwork 2003-07 (based on 490 tetrads)

Red = breeding confirmed = 25

Orange = breeding probable = 25

Yellow = breeding possible = 26

Total tetrads in which registered = 76 (15.5%)

Peregrine - 2003-07

Most of what we know about Peregrines in the county is due to a small but dedicated band of volunteers who undertake the leg-work. Assessing the total Peregrine population in any one year requires a reasonable amount of effort and knowledge of the particular “patch”. They can utilise alternative nest sites over quite long stretches of coast. So it usually takes quite a few field-recording hours, often involving long walks along the coast path, to prove territory occupancy and confirm breeding. Detailed recording close to the nest also requires experienced, licensed observers.

Approximately every 10 years the entire UK population is surveyed to assess changes at the national level. The breeding population in Pembrokeshire has been subjected to annual surveillance since the early 1960s, coordinated by Jack Donovan up to 1983 and by Bob Haycock since then.

By the time of the first (1984-88) Pembrokeshire breeding birds atlas fieldwork period, the Peregrine breeding population was recovering well in the county. Some 14 – 15 breeding pairs were recorded by 1983 and by the end of the atlas period they had been found in 51 tetrads. By 1991, 39 territories were known to be occupied and their numbers had recovered to at least pre-second World War levels. 

Between 2003 and 2007, the total number of tetrads in which Peregrines were found had risen to 69, an increase of about 35%. Annual surveillance of the breeding population recorded 43 – 49 confirmed occupied territories, about three times the number recorded in the mid 1980s.

In the mid-1980s, all but two occupied territories were on the coast. By 2003 - 07 the number breeding inland, at quarries or other man-made sites such as large industrial structures (oil refinery and power station buildings - the latter now demolished), had risen to eight and they had been recorded in the breeding season from at least 14 inland tetrads.

The breeding population appears now to have stabilised (see figure 3 below of population trends), although the trend towards inland breeding may still be growing. In some places, inland sites may be seasonal alternatives to coastal sites.

There are still threats to the population; sporadic incidents of persecution still occur, including fairly recent evidence of individual birds either being shot or poisoned, or of individual nests being disturbed.

Bob Haycock

Fieldwork 2003-07 (based on 490 tetrads)

Red = breeding confirmed

Orange = breeding probable

Yellow = breeding possible

Tetrads in which found = 69 (14.1%)

Gannet - 2003-07

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

Update on Monday, May 7, 2012 at 10:30AM by Pembrokeshire Avifauna committee

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).

Bob Haycock

Pembrokeshire Breeding Bird Atlas 2003-07

The Pembrokeshire Breeding Bird Atlas 2003-07 provides an update to the 1994 Birds of Pembrokeshire, covering the breeding species.

The Atlas of Breeding Birds of Pembrokeshire 2003-2007 is available as a print-on-demand publication by clicking here

THE MAKING OF THE ATLAS

Introduction

The county of Pembrokeshire is some 158,000 hectares (613 square miles) in extent, with its southern, western and northern boundaries all coastal. The climate is maritime, with strong oceanic influences found also in the type and distribution of fauna and flora.

A review of all the species of birds recorded in the county in all seasons is to be found in the "Birds of Pembrokeshire" by Jack Donovan and Graham Rees, published in 1994 and including a breeding bird atlas based on fieldwork done in 1884-88. This important publication provided a baseline on which to compare mapped distributions and population estimates of different species within the county.

The populations of any animals that can walk, fly, swim or crawl will change in numbers and distribution over a period of time, so that any atlas will become out of date over a period of years, decades or centuries. 

Biodiversity is the buzzword, and the need to know what species are where has become important, indeed a requirement, for planning and conservation purposes.

Trends towards milder and windier winters, and towards cloudier, wetter summers, may herald longer term climate change.  But there is already anecdotal evidence, as well as indications from country-wide surveys, that there are other changes happening in the natural world.

At a local level, it was decided that the "Birds of Pembrokeshire" should be updated.  This breeding birds atlas is first stage in that process.  It does, indeed, show that there have been changes, both losses and gains, within the 15 to 20 years between the two fieldwork periods

Methodology

On the 2nd September 2002 the Pembrokeshire Bird Group convened a meeting at “The Patch”, Furzey Park, Haverfordwest, to discuss the desirability of producing a new avifauna for Pembrokeshire.  All interested parties were invited to attend and those interested but unable to attend were encouraged to communicate their views.

The meeting agreed to go ahead with such a project and that it should encompass a breeding birds survey using a tetrad (2km x 2km) grid. To this end an Avifauna Committee was elected, comprised of Graham Rees (chair), Annie and Bob Haycock, Jane Hodges, Trevor Price, and Mike Young-Powell.

At their first meeting, the committee decided that the breeding survey should be the first aspect to be addressed. It was to run from 2003 to 2007 and to take the same form as the 1984-88 survey so that the two would be directly comparable.  The 1984-88 survey was the first in the county to use as fine a scale as the tetrad grid.  It was also the first attempt made to estimate the size of the breeding population of each species in the county.

Recording forms and accompanying instructions (see appendix IV) were printed and distributed in time for field work to begin in 2003. 

Data from completed recording forms, representing some 30,000 records from 490 tetrads, were entered on computer by a small team comprising John and Marion Best, Annie and Bob Haycock, Fiona and Trevor Price, using the computer software package MapMate. A summary of the records from the 1984-88 survey was similarly entered, so that comparable maps could be generated.

The methods used for atlas fieldwork followed those of The Atlas of Breeding Birds in Britain and Ireland (Sharrock 1976) but recorded at the tetrad level rather than hectad (10km x 10km) level. For our local atlas however, adjustments have been made in as much as the islands of Grassholm, Caldey, Skokholm and Ramsey have been regarded as occupying one tetrad each, while Skomer and Middleholm have been treated as a composite tetrad. As in that first national atlas, the final maps are populated with small dots to indicate that a species was present during the breeding season, medium-sized dots to show that it probably bred, and large dots to show that breeding was confirmed, as shown in figure 1:

The example map above shows the data entry record card in MapMate that helps generate distribution maps. Records entered this way gradually build up a growing series of distribution dots on a map, Each record entered represents a breeding registration for a particular species in a particular tetrad. The species in this case is House Martin and the tetrad is SN04L (SN0442 Trwyn y Bwa).

The more visits that are made to a particular tetrad, the more information there is behind each dot providing an eventual final outcome - in this case the largest dot showing confirmed breeding.  In other tetrads medium dots represent probable breeding (e.g. bird showing territorial behaviour or visiting potential nest site, and probably went on to breed successfully) while the small dots show that the species was present in a tetrad at some time during the survey, but no evidence was found to indicate that it was doing more than feeding or resting there.

Another team of volunteers, comprising Graham Rees, Bob Haycock, Jane Hodges, Steve Sutcliffe, Paddy Jenks and Richard Dobbins wrote the individual species accounts.  Annie Haycock then assembled the maps and texts into this volume.

The map below shows the tetrads covered in the 1984-88 atlas (in yellow) and 12 extra tetrads (blue dots) covered during the 2003-07 period.  These were all peripheral tetrads, either coastal or along the county boundary, and including only a small amount of land.

Population estimates

The 2003-07 Pembrokeshire breeding survey was deliberately undertaken using the same methodology as the previous 1984-88 survey, so that the two were directly comparable. It should, therefore prove useful in assessing biodiversity, species distribution changes and perhaps in evaluating the effects of changes in weather patterns over the period.

However, there are limitations to the information gathered by this kind of survey.  It is basically a presence or absence survey, with some additional value in terms of proving whether or not species was breeding throughout the area.  Nonetheless, it does give a reasonable indication of the spatial distribution of each species, and whether a species is localised, is widespread occurring in most tetrads, or is widespread but scattered.

The results take no account of time spent in the field in each tetrad, or of observer bias or competence. Figure 2 shows the number of species recorded in each tetrad in each atlas period (all species are included, whether or not they showed signs of breeding).  In the later period there appears to have been a shift away from the north, with more species recorded in the south-east and on the St. David's peninsula.  While some of this shift may be genuine, some of it is likely to be observer bias as people inevitably record closer to their home areas unless directed to do otherwise.

People were not asked to count birds whilst recording in tetrads during the main 2003-07 survey.  The limited population data collected as part of the BAP breeding survey applied to nature reserves and other special areas, and so was not directly applicable to the county as a whole. 

For the 1984-88 atlas, population estimates were compiled from survey results combined with extensive personal experience (of the authors) within the county (Donovan & Rees 1994). These estimates provided a baseline used to inform population estimates for the 2003-07 atlas. For example, an increase in the number of tetrads recorded for a species was assumed to have the same proportional increase in population. For a few species, e.g. Yellowhammer, anecdotal evidence indicated that has there has been a thinning out of the population, while for others, such as Chough, long term surveillance of nest sites showed there has been an increase in the breeding density, at least in some areas.  This approach therefore has limitations.

It will be noticed in the accounts for many species, that the results of the 1988-91 National Atlas  (Gibbons et al) have been used in testing the original estimates made following the pioneering 1984-88 local atlas.  For a few species, this has resulted in a revision of the original local population estimate and is explained in the individual species text.

The BTO/JNCC/RSPB Breeding Bird Survey (BBS), which came into being in 1994, also provides a useful tool for estimating populations. This survey is carried out nationally, and provides indices of the populations of birds in Britain in summer.  These indices are based on both the changes in numbers of each species counted along two parallel 1km transects in a 1km square, and on changes in the percentage of squares in which they occur. 

For most species in this atlas, a new population size has been estimated, based on a combination of data from the 1984-88 fieldwork, the 2003-07 distribution maps, the results from the 1988-91 National Atlas, and the BBS indices for Wales.  The current National Atlas (fieldwork in progress at the time of this publication), backed by extensive information from other bird research and survey, will undoubtedly become useful in further refining these population estimates in due course. This new information will be considered in the more comprehensive Pembrokeshire Avifauna.

For other species, notably seabirds, chough and peregrine, more specific data are collected annually and this allows a more detailed assessment of population size to be made. Seabirds on the Islands and the Castlemartin coast are counted annually for the Seabird Monitoring Programme administered by the JNCC (www.jncc.gov.uk/page-1550).  For all these species, there is more discussion about the population changes in the species accounts.

Density of recorded species in each atlas period

1984-88 density map. The smallest dots represent 2 species, the largest represent 86 species.  The counts include non-breeding species.

2003-07 density map. The smallest dots represent 2 species, the largest represent 81 species. The counts include non-breeding species.

The average number of species per tetrad is 35.

INTERPRETING THE SPECIES ACCOUNTS

For those species of particular conservation concern, the designation of red or amber-listing, or UK BAP or LBAP is given in the title line.  Further information about these designations is given in appendix III.

A brief introduction is given for each species, followed by comments about changes in distribution and population, and a discussion of problems with calculating such changes.

Maps are not reproduced for all species, where the breeding distribution is so limited that it can readily be expressed in the text, e.g. Gannet. For some scarcer and legally protected (Schedule I of the Wildlife and Countryside Act) species, maps are provided at a 10 kilometre square level.

For the majority of species, a table shows the total number of tetrads in which the species was found, plus the numbers of tetrads that registered “confirmed”, “probable” or “possible” breeding during each atlas period.  Note that for some species, for example rooks and other colonial nesting species, birds foraging in fields or in flight do not give any indication of the location of their nest sites, which may be some distance away, and therefore such "possible" breeding records have been excluded.  For other species, for example skylark, the distribution was based largely on birds singing on more than one date in the same place to show they are holding territory. In these instances the maps show mostly probable breeding.