Grey Wagtail - 2003-07

During the 1984-88 tetrad survey, Grey Wagtails were found to be widespread in Pembrokeshire, breeding on all major and many of the minor streams and rivers, from the Preseli Hills to the coast.  The results of the 2003-07 tetrad survey suggest that they are still widespread in the county, although there have been some localised losses, e.g. parts of the Western Cleddau catchment area and from watercourses to the south and east of Haverfordwest.  Gains have occurred in eastern parts of Pembrokeshire and in one or two tetrads in the west of the county. The data also indicate a 31% increase in the number of tetrads where breeding was confirmed, and a 12% increase in the number of tetrads where breeding was probable. The BBS index suggests a population change at UK level between 1994 and 2007 of +26%.

In general, Grey Wagtails appear to be doing well in the county, possibly reflecting the recent trend towards milder winters which will have helped to improve and maintain winter survival, hence recruitment to the breeding population.  They are sensitive to prolonged spells of cold weather, although population crashes are usually followed by quite rapid recovery. Other factors that are likely to influence Grey Wagtail breeding populations include water quality and the management of watercourses and associated vegetation by the sides of the banks. Operations such as the removal of gravel shoals could be detrimental, as could clearance of mature bank-side vegetation.

Following the 1984-88 tetrad survey, the breeding population was estimated to be around 450 pairs, based on an average of four pairs per tetrad. An estimate of the breeding population following the 2003-07 tetrad survey would probably be very similar, i.e. around 450 pairs.

Jane Hodges

Fieldwork 2003-07 (based on 490 tetrads)

Red = breeding confirmed = 58

Orange = breeding probable = 24

Yellow = breeding possible = 32

Total tetrads in which registered = 114 (23.3%)

Rock Pipit - 2003-07

Rock Pipits breed all around the rocky open coast on mainland Pembrokeshire, and on the offshore islands, including Grassholm, some 12 miles west of the mainland, where they nest on/in cliff faces. They also occur within the sheltered Milford Haven Waterway, on rocky shores backed by cliffs. 

The data from the 2003-07 tetrad survey suggest that, although the Rock Pipit remains a common breeding resident on the islands and mainland coast, there have been changes in the distribution of breeding pairs, and probably in the overall number of pairs.

The data indicate that Rock Pipits have disappeared from 20 tetrads in which they were recorded as confirmed breeding in the 1984-88 tetrad survey, which represents a 9% rate of decline.  On the other hand, there was a significant increase, an almost doubling, of the number of tetrads where Rock Pipits were recorded as “probable breeding”.

 A look at the tetrad map confirms that Rock Pipits have disappeared as a breeding species from the upper Daugleddau Estuary, much of the inner and outer sections of the Milford Haven Waterway, and from the open coast in the Amroth/Wisemans Bridge/Saundersfoot area.  Elsewhere on the coast, it is worth noting that several of the tetrads where Rock Pipits were recorded as probable breeding coincide with parts of the coast that are particularly difficult to survey from the cliff tops.  Observers may have erred on the side of caution because they were unable to obtain sufficient evidence to confirm breeding in these tetrads.  If this is the case, then it is likely that the distribution of the breeding population on most of the outer coast remained stable between the two tetrad surveys.

In terms of the size of the breeding population, the situation is less clear.  The Pembrokeshire Bird Report for 2003 notes that there were 30 territories occupied by Rock Pipits on Skokholm Island.  A comparison between this and the figure of 41 occupied territories quoted for Skokholm Island in 1990  suggests a decline of up to 27% in breeding Rock Pipits on the island during that period. 

Reasons for the decline recorded on Skokholm Island are not immediately obvious, although a lack of insect food at critical stages in the breeding cycle, perhaps resulting from poor weather may be a factor, and it may not be representative of the population as a whole. A 9% decline in the number of tetrads in which breeding was confirmed between the two tetrad surveys, however, would put the total population at around 900 pairs.

Jane Hodges

 

Fieldwork 2003-07 (based on 490 tetrads)

Red = breeding confirmed = 51

Orange = breeding probable = 40

Yellow = breeding possible = 11

Total tetrads in which registered = 102 (20.8%)

Meadow Pipit - 2003-07

Meadow Pipits are ground-nesters, in open, rough grassland, heathland and moorland, where at an important host-species for the Cuckoo.  In Pembrokeshire, Meadow Pipits can be found on rough grazing on the coastal slopes and headlands, on the islands, Ramsey, Skomer and Skokholm in particular, on lowland heathlands and on the slopes and tops of the Preseli Hills where they are the most numerous breeding passerine.  Grasslands on the old, disused airfields such as Templeton, St Davids and Brawdy, which are extensively grazed, are also important for Meadow Pipits.  Reseeded permanent pasture that is intensively grazed by dairy cattle or sheep is unsuitable for Meadow Pipits: the short swards provide insufficient cover for nesting, and disturbance from livestock grazed intensively is a hazard. Sheep are known to consume the eggs of Meadow Pipits.

Following the 1984-88 tetrad survey, it was noted that although still a common species, the Meadow Pipit had declined since, for example, Lockley’s review in 1949, in which he describes the Meadow Pipit as a common species.  In between the two tetrad surveys, further changes occurred.

These figures suggest that changes in the distribution of Meadow Pipits have been both subtle and localised, although overall, they point to a decline in the breeding population.  The distribution map shows that whilst there have been gains in some areas, there are now significant areas of Pembrokeshire away from the principal peninsulas, coastal fringes, and the Preseli Hills, where the Meadow Pipit is absent as a breeding species.  Reasons for the overall decline and fragmentation of the breeding population are almost certainly linked to changes in agricultural practices, in particular farms moving out of more extensively mixed farming regimes into intensive dairy and sheep farming.

Following the 1984-88 tetrad survey, it was estimated that there were about 4,000 breeding pairs, based on an average density of 20 pairs per tetrad. Assuming that Meadow Pipits still occur at a similar density, then based on the number of tetrads where breeding was confirmed or probable during the 2003-07 tetrad survey, the breeding population is thought to be approximately 3,220 pairs.

Jane Hodges

Fieldwork 2003-07 (based on 490 tetrads)

Red = breeding confirmed = 66

Orange = breeding probable = 95

Yellow = breeding possible = 31

Total tetrads in which registered = 192 (39.2%)

Tree Pipit - 2003-07

Since the 1984-88 tetrad survey, Tree Pipits have undergone significant declines as a breeding species in Pembrokeshire.

These data suggest that Tree Pipits have disappeared from ca. 60% of the tetrads in which they were recorded in the 1984-88 survey.  A glance at the tetrad map confirms that, whilst the strong bias in distribution remains east of a line from Newport on the north coast to the east of the Daugleddau Estuary, Tree Pipits are now absent from the majority of tetrads in which they were recorded in the first tetrad survey to the west of this line.  The 25 tetrads in which Tree Pipits were recorded as confirmed or probable breeding in the 2003-07 survey are clustered around the Gwaun Valley and lower flanks of the Preseli Hills, and around the Canaston/Minwear Woods and areas south to Lawrenny and Martletwy in mid Pembrokeshire.

The dramatic rate of decline suffered by this species in Pembrokeshire far outstrips the national rate of decline. The BBS data for the UK during the period of 1994 and 2007 indicated a rate of change of -11% and raises questions about its future in the county.  The reasons for the rapid decline in the breeding population of Tree Pipits are not known, although factors such as loss or deterioration in the quality of breeding habitat are likely to have played a major part. 

Habitat loss has almost certainly occurred, as forestry plantations have either been clear-felled or have matured and closed-over; woodland glades have been in-filled by scrub or bracken encroachment, and structurally diverse edges to semi-natural habitats have been lost, as a result of changes in farming practices.  Other key factors are likely to include survival of birds on their sub-Saharan wintering grounds. The 1984-88 survey used an estimated average density of 10 pairs per occupied tetrad to arrive at a county population estimate of 800 pairs. The breeding population during the 2003-07 survey, using the same density estimate, was probably 250 pairs, or less if the average density had decreased.

Jane Hodges

 

Fieldwork 2003-07 (based on 490 tetrads)

Red = breeding confirmed = 1

Orange = breeding probable = 24

Yellow = breeding possible = 5

Total tetrads in which registered = 30 (6.1%)

House Martin - 2003-07

Most House Martins arrive in Pembrokeshire between early and mid April, although there have been sightings as early as February.  

House martins are highly dependent on buildings for nest sites with up to 99% of the breeding population building mud nests, or utilising artificial nest boxes positioned high-up on walls beneath over-hanging eaves, which protect the nest and its contents from adverse weather. In Pembrokeshire, a small proportion of House Martins nest in sea caves, or beneath over-hangs on sea cliffs. Colonies can be found, for example nesting in/on sea cliffs to the south of Ceibwr; at Nolton Haven and on the Castlemartin coast.

The 1984-88 tetrad survey confirmed that House Martins are widely distributed as a breeding species across the county.  A comparison between this and the 2003-07 tetrad survey suggests a stable or slightly increasing breeding population:

The tetrad map illustrates where localised changes in the distribution of breeding House Martins have occurred in between the two tetrad surveys. House Martins are absent as a breeding species from all the offshore islands, with the exception of Caldey Island, where it was recorded as “probable breeding” during the 2003-07 tetrad survey.  They are also absent from the tops of the Preseli Hills and from heavily wooded areas.

Whilst the breeding population of House Martins has generally remained stable or increased overall, localised losses from some tetrads could be due to a number of factors, which may also hold the key to their future as a breeding species in the county.  These factors include future availability of suitable nest sites. It is vital that building renovations, as well as new buildings take account of their nesting requirements if they are to continue to grace our skies. The availability of mud for nest-building is also vital as this resource can be easily lost e.g. as a result of tidying up muddy seepages, hollows and puddles. A single source of mud may supply the entire House Martin population on farms or in small settlements. Other key factors include abundance and distribution of aerial insects.

Following the 1984-88 tetrad survey, the total breeding population of House Martins in the county was estimated to be around 4,000 pairs (an average density of 20 pairs per tetrad was assumed).On this basis, an increase of 16% of tetrads where breeding was confirmed during the 2003-07 tetrad survey suggests a total breeding population of about 4,700 pairs.

Jane Hodges

 

Fieldwork 2003-07 (based on 490 tetrads)

Red = breeding confirmed = 235

Orange = breeding probable = 17

Yellow = breeding possible = not included

Total tetrads in which registered = 252 (51.4%)

Swallow - 2003-07

Swallows are highly dependent on the availability of suitable buildings for nest sites.  They nest in barns and other outbuildings, porches, sheds and garages, and are often semi-colonial particularly in farm buildings where livestock are kept.  More unusual nest sites have included a sea cave in Martins Haven and a disused underground heating duct at Stackpole.  They have nested in the public conveniences at Martins Haven for many years. Swallows have also bred successfully in some of the rooms in Carew Castle. Swallows are aerial insect feeders, and forage over a range of semi-natural habitats such as freshwater and salt marsh; open water; open, wooded areas and scrub, and over pasture especially if it is grazed by livestock, e.g. cattle and horses.

Data obtained during the 2003-07 tetrad survey suggests relatively little change in the distribution of breeding pairs of Swallows in the county (see map).

The data show an increase of 13% in the number of tetrads where breeding was confirmed between the two tetrad surveys. The map shows a largely unchanged distribution of tetrads in which breeding was confirmed or probable. A few gaps have however, opened up, for example on the St David’s Peninsula, on the Pencaer Peninsula and in one or two parts of mid and north Pembrokeshire away from the coast.  These appear to be quite small-scale, localised losses that may be linked to the loss of suitable nest sites, e.g. as a result of conversion of outbuildings to dwellings. They may also be a result of changes in the distribution and abundance of aerial insects, following changes in land management practices.

Following the 1984-88 tetrad survey, it was estimated that at an average density of 20 pairs per tetrad, there were at least 8,500 pairs of Swallows in the county. A 13% increase in the number of tetrads where breeding was confirmed during the 2003-07 tetrad survey suggests that the breeding population is around 10,000 pairs.

Jane Hodges

Fieldwork 2003-07 (based on 490 tetrads)

Red = breeding confirmed = 338

Orange = breeding probable = 74

Yellow = breeding possible = 22

Total tetrads in which registered = 434 (88.6%)

Sand Martin - 2003-07

Trans-Saharan migrants, Sand Martins usually arrive in Pembrokeshire in March, but were recorded as early as the 14th February during the 2003-07 Atlas survey period.

In Pembrokeshire, Sand Martins nest in sandy/gravelly river banks, in soft sandy/gravelly sea cliffs and in artificially created habitats, notably sand and gravel pits.  They are highly colonial, and return to the same colony site, although they generally dig fresh nesting burrows, to avoid parasitic infestation.  Sand Martins feed mostly on aerial insects, foraging over freshwater, wetlands and pasture, preferably grazed by cattle.  They generally avoid urban and densely /wooded areas.

As illustrated by the map, on the mainland colonies are scattered on the coast and inland. With the exception of a cliff site in the Freshwater West area, all the colony sites were found in mid and north Pembrokeshire. Sand Martins are absent from the offshore islands.

At first glance, a comparison between the two tetrad surveys suggests a significant expansion in the breeding population of Sand Martins. A closer inspection of both the numbers of tetrads where Sand Martins were recorded and the tetrad map, however, revealed a 10% decrease in the number of tetrads where breeding was confirmed.  There were also changes in distribution of colonies: They have disappeared from four tetrads in between the two surveys. This was counter-balanced by the recording of several new colonies, mostly on the coast.

The two sets of tetrad data for “confirmed” and “probable” breeding are very similar, although the tetrad map clearly suggests changes in distribution of colony sites.  This could well indicate that suitable nesting habitat is a finite resource in Pembrokeshire, hence a potential limiting factor on the distribution and size of future breeding colonies of Sand Martins.

Sand Martin colonies tend to be transient, and will move if a particular sandy bank becomes over-stabilised.  On rivers, fresh bank falls that occur whilst rivers are in spate will be preferred to stable bank/cliff faces that may become over-gown.  Similarly, artificial sites e. g. sand and gravel pits will also be deserted once exposed faces become too stable, hence unsuitable for Sand Martins, they even move around within active sand pits. This is likely to be a contributing factor in the changes in distribution noted between the two surveys: sites may have fallen into disuse because they no longer offer suitable exposed, soft sandy/gravelly cliffs which birds can burrow into, yet are firm enough for the burrows to remain intact during the breeding season.

The overall size of the breeding population is not thought to have changed significantly between the two tetrad surveys, and is thought to be between 70 and 100 pairs ( the population estimate given in Donovan and Rees (1994) was based on accurate colony counts).

Jane Hodges

 

Fieldwork 2003-07 (based on 490 tetrads)

Large dots = breeding confirmed = 11

Medium dots = breeding probable = 2

Total tetrads in which registered = 13 (2.7%)

Skylark - 2003-07

The 1984-88 tetrad survey revealed that the Skylark was one of the most widespread breeding species in Pembrokeshire, being absent from only ca. 35 tetrads. During the  1988-91 National Atlas it was also found to be one of the most widespread breeding species in the UK. The breeding population in Pembrokeshire, based on an average of 15 pairs per tetrad, was estimated to be around 8,000 pairs. 

Data from the 2003-07 Pembrokeshire tetrad survey indicates that the Skylark, as a breeding species, has disappeared from ca. 33% of the tetrads in which it was previously recorded.  This represents a significant decline, which may be happening at a faster rate in Pembrokeshire than in the UK as a whole, as BBS data indicate that between 1994 and 2007 the UK Skylark population decreased by 13%. The breeding population in Pembrokeshire is now probably nearer to 5,000 pairs.  The tetrad map indicates that large gaps in the distribution of breeding skylarks have opened up in the area to the north of the Nevern Valley, towards Poppit and Cemaes; in the area between the Eastern Cleddau and the Carmarthenshire border, and in mid-Pembrokeshire, away from the coastal strip and Preseli Hills.

The Skylark is a ground-nesting species, with a strong preference for open countryside, with rough pasture, heathland and moorland.  In the winter, Skylarks utilise winter stubbles, ungrazed grassland, fallow land and coastal habitats such as sand dunes and saltmarsh.  Reasons for the disappearance of Skylarks from parts of Pembrokeshire are likely to include changes in farming practices, such as from mixed farming to intensive dairy farming and cultivation of grass for silage, a trend that was alluded to in Donovan and Rees, (1994). 

Winter foraging habitats may also have been lost due do the trend towards autumn-sown rather than spring-sown cereals, in which valuable winter stubbles have disappeared, thus affecting winter survival of the breeding population.  The islands and peninsulas, such as Pencaer, St Davids, Marloes and Castlemartin, and the Preseli Hills are likely to become increasingly important as strongholds for Skylarks. Inland, old airfields such as Templeton, St Davids and Brawdy are hotspots for Skylarks, supporting relatively high densities of breeding pairs.

Jane Hodges

 

Fieldwork 2003-07 (based on 490 tetrads)

Red = breeding confirmed = 41

Orange = breeding probable = 227

Yellow = breeding possible = 15

Total tetrads in which registered = 283 (57.8%)

Lesser-spotted Woodpecker - 2003-07

Despite their apparent scarcity, with usually only a handful of records received in any one year, the number of tetrads in which they were found was remarkably similar between the two atlas periods, 1984-88 and 2003-07. Whilst breeding was only confirmed in one tetrad, it is acknowledged that Lesser Spotted Woodpeckers are difficult to prove breeding and this decline was more or less balanced by the number of tetrads that registered probable and possible breeding evidence.

In the earlier atlas period, they were patchily distributed, with concentrations along the Western Cleddau river valley from around Millin Pill northwards. They were also reasonably well represented in tetrads further north, generally around the Teifi valley area, while another small concentration occurred in the south-east.

During the recent atlas period there was no evidence of breeding in the Teifi valley, although birds were present and no records at all from the south-east. They were recorded in the Western Cleddau but most records came from the Eastern Cleddau catchment. Whether this is due to a genuine contraction in range is not clear. Because this is a relatively difficult species to find, recorder bias cannot be ruled out. During 1984-88 there were no breeding records south of Milford Haven but breeding occurred between the two atlas periods at Orielton in 1995 (nest with young). In the 2003-07 period breeding may have occurred at Orielton again but was not confirmed.

Donovan and Rees (1994) suggested that Lesser Spotted Woodpeckers had been under-recorded and did not make an estimate of the Pembrokeshire population based on 1984-88 records. Assuming that the number of tetrads in which they were found reasonably represents the breeding population, this may be not less than 19 – 20 pairs in both atlas periods, suggesting population stability.

River-bank tree management may be an issue for this species, but conversely they may also be prospering from river corridor management, where bank-side woody vegetation has been fenced from grazing along lengths of river as part of riparian habitat management schemes. More survey effort is needed to determine breeding density in sample riverine habitat, as well as the relative status of the Western and Eastern Cleddau river valleys, apparently their core breeding areas.

Bob Haycock

Fieldwork 2003-07 (based on 490 tetrads)

Red = breeding confirmed = 1

Orange = breeding probable = 6

Yellow = breeding possible = 12 

Total tetrads in which registered = 19 (3.9%)

Great-spotted Woodpecker - 2003-07

The number of tetrads in which Great Spotted Woodpeckers were found increased significantly between 1984-88 and 2003-07, from 172 to 254 - almost 48%. With the exception of a small decline in the number of tetrads registering possible breeding, the number of tetrads where confirmed and probable breeding was recorded increased by around 67% and 122% respectively. According to BBS information the population index for this species has risen by 196% between 1994 and 2007 in Wales overall.

Donovan and Rees (1994) remarked that although much harder winters of the early 1960s apparently had no effect, the cold snap in winter 1979 was thought to have reduced the population substantially, based partly on observations at Hylton Woods. Since about 1990, there has been a remarkable run of generally mild winters so Great Spotted Woodpeckers may have prospered as a result.

By the end of the 1984-88 survey period, Donovan and Rees estimated that there was an average density of three or four pairs per occupied tetrad, providing a Pembrokeshire population of about 500 – 700 pairs. But they concluded that the population was undoubtedly greater prior to 1979. This woodpecker species is certainly one that currently seems to have prospered recently, and over the last 20 years seems to have recovered quite well.  Using the 1980s population estimate, based on the number found in tetrads, there may now be at least 760 to 1,000 pairs breeding in Pembrokeshire. 

Bob Haycock

 

Fieldwork 2003-07 (based on 490 tetrads)

Red = breeding confirmed = 75

Orange = breeding probable = 109

Yellow = breeding possible = 70

Total tetrads in which registered = 254 (51.8%)

Green Woodpecker - 2003-07

During the 20 year period between 1984-88 and 2003-07 there has been a quite dramatic decline in Green Woodpecker distribution across Pembrokeshire, indicated by a 77% decrease in the number of tetrads in which they were found. This decline is contrary to the BBS population index, which appears to indicate an overall 48% increase across Wales as a whole between 1994 and 2007. Within Pembrokeshire, the population appears to have shrunk towards the south and south-east. Apart from some outliers on the St David’s peninsula and in the Gwaun Valley, they now appear to have all but disappeared in the north.

Examination of the 1988-91 National Atlas is also revealing. Pembrokeshire and other counties in Wales (and also notably in Cornwall), recorded many more 10 km-squares with losses of confirmed breeding Green Woodpeckers, than  gains between the first national breeding birds atlas (1968–72) and the second atlas, 20 years later. This seems to much more closely represent the trends found in the local atlas, compared with the BBS population index. Even from the 1984-88 atlas survey, Donovan and Rees regarded the Green Woodpecker distribution as patchy across the county. They estimated that the average density may have been as high as one to two pairs per occupied tetrad and suggested a population then of about 140 – 280 pairs. Translating this to 2003-07 would therefore suggest a population of about 32 – 64 pairs. Even this seems to be a high number, considering how difficult they were to find during the five years of atlas fieldwork.

Up to 2007 at least, Stackpole National Nature Reserve, on the Castlemartin peninsula remained as one of their most reliable breeding areas, where one or two pairs regularly nested during the atlas survey period. Here there are still reasonably healthy ant populations in unimproved invertebrate-rich dune and maritime grassland, supporting yellow ant hills at a density of up to 550 per hectare. Green Woodpeckers feed over Stackpole Warren but have also been found searching for food in the limestone-crevices on the sea cliffs. 

Just why Green Woodpeckers appear to be in steep decline in Pembrokeshire is unknown. Recent on-line species maps, from the early period of the 2007 – 11 joint national winter and breeding atlas is also revealing. Provisional distribution maps suggest that there has been a contraction in their population in Wales. This is particularly evident in neighbouring Ceredigion to the north, where breeding evidence is fairly patchy and they also appear to be largely absent from west Carmarthenshire.

Is climate an issue? Could changes in grassland management have led to a loss of invertebrate prey, especially ants? Could this be subtly linked to local declines in the Rabbit population since the arrival of viral haemorrhagic disease in the early 1990’s, on top of already established seasonal outbreaks of myxomatosis? Have there been subtle changes in woodland management that may be a contributing factor? Whatever the reason or combinations of factors involved, further local research is needed to identify the main causes and to see if positive management can be introduced to halt the decline.   

Bob Haycock

 

Fieldwork 2003-07 (based on 490 tetrads)

Red = breeding confirmed = 3

Orange = breeding probable = 20

Yellow = breeding possible = 9

Total tetrads in which registered = 32 (6.5%)

Kingfisher - 2003-07

The confirmed and probable breeding records total 16 for both the 1984 - 88 and the 2003-07 surveys. The estimated 50 breeding pairs during the former survey was based on these registrations, so there has probably been no change since. However there was almost a 50% reduction in the possible breeding category, that is to say birds seen in apparently suitable habitat during the nesting season. Why this is so has not been resolved. Kingfishers can suffer increased mortality during cold spells but no such weather occurred during the review period. Pollution incidents may affect fish stocks and therefore Kingfishers, but in general water quality has improved post the 1980’s and no such effect was experienced in the core breeding area. The most likely explanation seems to be under-recording, for bright and colourful as Kingfishers are, they can be elusive and easily overlooked.

Graham Rees

Fieldwork 2003-07 (based on 49o tetrads)

Red = breeding confirmed = 8

Orange = breeding probable = 8

Yellow = breeding possible = 16

Total tetrads in which registered = 32 (6.5%)