Reed Warbler - 2003-07

This summer visitor’s appearance is plain, with unstreaked brown upperparts and buff underparts.  Its slow chattering song is usually the first indication of its presence in the deep cover of reedbeds, its principal habitat. Its nest is intricately woven around the stems of reeds.

The Reed Warbler has slowly expanded its range in Britain from about the 1960’s, in Pembrokeshire from1974, with breeding proven in 1975. By the time of the 1984-88 survey an estimated 60 pairs were breeding in the county. The estimate was made after some time spent in the main localities and was based largely on singing birds. Assessing the Canaston reedbed (also referred to as Minwear or Slebech reedbed) was made particularly easy because the local shooting syndicate had cut rides through the reeds the previous winter. (Note that although the largest concentration in the district has been the Teifi Marshes, the majority of them have been in Ceredigion, so only a small fraction qualified for inclusion in Pembrokeshire assessments).

By the close of the 2003-07 survey an increase of 48% in distribution had been plotted but it is unlikely that this represents an increase in population of this magnitude. New sites were in small areas of reeds around ponds and along river banks, which did not have the carrying capacity of major reedbeds. On the premise that about 10 pairs were added in these new sites and that the main population remained stable, as it has nationally, there were probably about 70 pairs nesting in Pembrokeshire by 2007. Although the population estimates have been given in pairs, they are mainly based on singing birds and some of these may not have attracted mates, which is not uncommon among Reed Warblers.

Graham Rees

Fieldwork 2003-07 (based on 490 tetrads) 

Red = breeding confirmed = 7

Orange = breeding probable = 24

Total tetrads in which registered = 31 (6.3%)

Sedge Warbler - 2003-07

The Sedge Warbler is a small, chubby warbler with brown upperparts streaked black, creamy white underparts and a broad cream stripe above the eye. Its varied chattering song is often delivered whilst it is perched in full view or in its song–flight. It is to be found mostly in damp places like reedbeds, bogs and around ponds. Its nest is placed in bushes or tall vegetation, near or on the ground. It is a summer visitor.

The UK population level has varied considerably over the years, affected mainly by varying rainfall in its winter quarters in West Africa. Analysis of various data sets gathered by the BTO shows year to year fluctuations, with similar levels of population in the UK in the years 1988 and 2007, which is relevant to the two local surveys. The 2003-07 survey results show an almost 10% increase compared with those of 1984-88.This suggests that about 700 pairs were nesting in Pembrokeshire at the end of 2007, compared to 650 pairs in 1988.

Graham Rees

 

Fieldwork 2003-07 (based on 490 tetrads) 

Red = breeding confirmed = 27

Orange = breeding probable = 109

Yellow = breeding possible = 11

Total tetrads in which registered = 147 (30%)

Grasshopper Warbler - 2003-07

Interpretation of the comparative results of the two surveys is difficult. Young conifer plantations occupied during the earlier survey had matured to a state of unsuitability by the latter one. The BBS found an increase, on a UK national basis, of 68% since 1994 and by 24% between 2006 and 2007. This may have been in response to favourable conditions at their African wintering grounds resulting in increased survival.

The 1988-91 National Atlas indicated maximum abundance in Pembrokeshire, so it seems safe to apply the UK wide BBS figure to the county plot. This being so, there were probably 480 – 670 pairs breeding in Pembrokeshire at the end of 2007, compared with an estimated 400 pairs in 1988.

Graham Rees

Fieldwork 2003-07 (based on 490 tetrads) 

Red = breeding confirmed = 2

Orange = breeding probable = 83

Yellow = breeding possible = 11

Total tetrads in which registered = 96 (19.6%)

Cetti's Warbler - 2003-07

Most records of Cetti's warblers are of singing males being heard. Since its colonisation, which began at Rhoscrowther in 1983, following the first one recorded at Bosherston in the winter of 1968, breeding has been variously established by trapping females with brood patches, seeing adults carrying food for nestlings, fledglings fresh out of the nest being observed and juveniles trapped at the close of the nesting season. Males are polygamous, serving up to four females, so singing males represent territories rather than pairs.

During the 1984-88 survey they were recorded at Rhoscrowther, Kilpaison, Pwllcrochan, Penally, Tenby and the Teifi Marshes, in a total of seven tetrads. Between surveys they were also found in the breeding season at Freshwater East, Castle Martin Corse and Llangloffan Fen. Numbers grew progressively at the Teifi Marshes to reach 23 singing males by 1995, all bar three of these being in Ceredigion, a short cold snap in the winter of 1996 almost eradicating them. By the time of the 2003-07 survey there were two singing males in the Pembrokeshire part of the Teifi Marshes, others being recorded at Tenby, Penally, the Ritec and at Goodwick Moor where fledglings were seen in 2006, covering a total of five tetrads.

Graham Rees

 

Fieldwork 2003-07 (based on 490 tetrads) 

Red = breeding confirmed = 1

Orange = breeding probable = 4

Total tetrads in which registered = 5 (1%)

Mistle Thrush - 2003-07

The 1984-88 survey found Mistle Thrushes to be more numerous in the south and north east of the county than elsewhere. The 2003-07 survey shows a much more even distribution across the whole area, other than remaining thinly spread in the far west, over all amounting to a 29% increase. The BBS calculated a 6% increase in Wales between 1994 and 2007. Applying this to the 2003-07 records for Pembrokeshire suggests a breeding population of about 1,900 pairs compared to the estimate of 1,400 pairs during the previous survey.

Graham Rees

Fieldwork 2003-07 (based on 490 tetrads)

Red = breeding confirmed = 131

Orange = breeding probable = 118

Yellow = breeding possible = 27

Total tetrads in which registered = 276 (56.3%)

Song Thrush - 2003-07

The song thrush is widespread across the county, but absent from the hill tops and all of the islands save the partially wooded Caldey, although it nested at Skomer in 2006. Around prime woodland, densities of up to 40 territories per square km have been recorded, in coastal areas as low as two per square km. The county estimate of 6,000 pairs made at the conclusion of the 1984-88 survey was based on an average density of 15 pairs per tetrad, which accorded with the slightly later UK national average used in the 1988-91 National Atlas. Since then the BBS has calculated a 24% increase in Wales between 1994 and 2007. If this increase is applied to the findings of the 2003-07 survey, a population of 7,500 pairs breeding in Pembrokeshire at the end of 2007 is arrived at.

Despite Song Thrushes thriving across Wales, for the UK as a whole they are red-listed under the Birds of Conservation Concern 3 (Eaton et al., 2009).

Graham Rees

Fieldwork 2003-07 (based on 490 tetrads)

Red = breeding confirmed = 178

Orange = breeding probable = 215

Yellow = breeding possible = 11

Total tetrads in which registered = 404 (82.4%)

Blackbird - 2003-07

No change in distribution is evident when the results of the two breeding bird surveys are compared, Blackbirds being found everywhere in the county bar the hill tops and the smallest offshore islands. The 1988-91 National Atlas indicated high to maximum abundance in Pembrokeshire, suggesting a higher density than the UK average, so the estimated 100 pairs per tetrad used with the 1984-88 survey results was probably realistic at 45,000 pairs. Since then the BBS has calculated a 47% increase in Wales over the period 1994 – 2007. Applying this increase to the 2003-07 survey plot suggests the Pembrokeshire breeding population could have reached about 66,000 pairs by 2007.

Graham Rees

Fieldwork 2003-07 (based on 490 tetrads)

Red = breeding confirmed = 317

Orange = breeding probable = 128

Yellow = breeding possible = 10

Total tetrads in which registered = 455 (92.9%)

Wheatear - 2003-07

It was estimated that 400 pairs of wheatears were nesting in the county during the 1984-88 survey. The distribution found during the 2003-07 survey was essentially the same as in the previous one. It is therefore considered that the population remained unchanged. A decrease in the number breeding on Skomer was balanced by an increase in the number breeding on Ramsey. No evidence was found that the BBS assessment of a 19% decrease in Wales between 1994 and 2007 was applicable to Pembrokeshire. This may be because the Preseli Hills continued to be heavily grazed by sheep and coastal areas were maintained in a favourable condition by the PCNPA’s “Conserving the Coastal Slopes” Project, which may have partially compensated for any possible reduction in Rabbit numbers by reintroduction of grazing by livestock.

Graham Rees

Fieldwork 2003-07 (based on 490 tetrads)

Red = breeding confirmed = 36

Orange = breeding probable = 19

Yellow = breeding possible = 31

Total tetrads in which registered = 86 (17.6%)

Stonechat - 2003-07

The perky male Stonechat with its black head, ruddy breast and “tack–tack” call, accompanied by its browner mate, is frequently encountered in the county at all times of the year. Its distribution is mostly linked to that of gorse, be it associated with heather, bracken, grass or bramble. It has also demonstrated an ability to use new conifer plantations but this has proved to be a transient inhabitation, the habitat becoming progressively unsuitable with tree growth. Nests are usually sited low down in dense growth at the base of a bush or in a tussock.

Comparison of the two surveys indicates a spread from the coast in the St David’s area and in the Preseli Hills.  Distribution at the coast tended to be linear, with a lower density than found at the more extensive heathlands. Donovan and Rees (1994) postulated a county breeding population of 200 pairs based on the 1984-88 survey plot, coupled with extensive experience of the areas involved. This estimate has generally been accepted as realistic for that time, bearing in mind the deflating effect of the cold winter of 1982. They concluded that the population was below optimum at that time.

The BBS has indicated that the Stonechat population increased in Wales by 338% between 1994 and 2007, in response to a period when there were no severe winters, conditions which have favoured this triple brooded species. As the Pembrokeshire population has expanded its distribution during this period and increased density was apparent in many localities, it seems reasonable to apply the BBS findings to Pembrokeshire. This suggests a population of 650 – 700 pairs by 2007, equating to an average of four pairs per occupied tetrad.

Graham Rees

 

Fieldwork 2003-07 (based on 490 tetrads)

Red = breeding confirmed = 96

Orange = breeding probable = 58

Yellow = breeding possible = 13

Total tetrads in which registered = 167 (34.1%)

Whinchat - 2003-07

Fifty pairs were found during the 1984-88 survey, most of them about the lower slopes of the Preseli Hills but a few others spread in suitable habitat across the north of the county as far as the coast. The 2003-07 survey found that their distribution had been reduced by 70%. Those which were still breeding were in the Preseli Hills, save for probable breeding on the St. David’s peninsula. The few Possible breeding registrations were thought to have involved birds on passage. It was estimated that a maximum of 25 pairs were nesting by the end of 2007. Reasons for the decline are thought to include adverse conditions on the wintering grounds and changes in agricultural practice. Over-grazing in localities formerly occupied by Whinchats may have encouraged colonisation by Stonechats in some areas.

Graham Rees

Fieldwork 2003-07 (based on 490 tetrads)

Red = breeding confirmed = 7

Orange = breeding probable = 2

Yellow = breeding possible = 3

Total tetrads in which registered = 12 (2.5%)

Redstart - 2003-07

 The Redstart was considered to be a sporadic breeder in Pembrokeshire prior to the 1984-88 survey. Fieldwork during that survey revealed a previously unsuspected population nesting around the lower parts of the Preseli Hills, plus a few scattered pairs elsewhere. They were similarly distributed during the 2003-07 atlas, but found in 33% more tetrads. It is estimated that about 200 pairs were involved.

Graham Rees

Fieldwork 2003-07 (based on 490 tetrads)

Red = breeding confirmed = 21

Orange = breeding probable = 29

Yellow = breeding possible = 2

Total tetrads in which registered = 52 (10.6%)

Robin - 2003-07

Voted national bird of Britain, depicted on Christmas cards, and being conspicuous in gardens, Robins are recognised by most people. Widespread in Pembrokeshire they are found in most habitats, being absent only from the tops of the Preseli Hills, dense conifer plantations and the offshore islands, save for Caldey. However, they have bred from time to time at Skokholm and Skomer, and during the 2003-07 survey at Ramsey. Nests are placed on the ground, in trees, bushes, nest boxes and other man - made objects, they are versatile birds.

When the county breeding population estimate was made at the end of the 1984-88 survey, the only local census results available came from a few nature reserves, which were mostly wooded. On this basis an average density of 100 pairs per tetrad was applied to the distribution plot, suggesting a total of 43,000 pairs in Pembrokeshire. The National Atlas of 1968–72, using extensive BTO Common Bird Census and other census data, took an average of 60 pairs per tetrad. However the 1988-91 National Atlas includes an abundance map which showed Pembrokeshire contained areas of maximum and medium densities, suggesting a higher figure locally than the average UK value, probably about 20% higher at just over 70 per tetrad. Since then the BBS has indicated a 7% increase in Wales during the period 1994 – 2007. Applying these approximations to the 2003-07 survey results gives an estimate of about 40,000 pairs breeding in Pembrokeshire.

Graham Rees

 

Fieldwork 2003-07 (based on 490 tetrads)

Red = breeding confirmed = 284

Orange = breeding probable = 155

Yellow = breeding possible = 8

Total tetrads in which registered = 447 (91.2%)