Dunnock - 2003-07

Formerly inhabiting scrub in arctic–alpine areas and woodland in tundra eastward from Poland, it has expanded its range westward to occupy a variety of lowland habitats. In Pembrokeshire it has become widespread, being absent only from the tops of the Preseli Mountains and the smallest offshore islands. Its nests are well concealed in bushes, hedges, trees or on banks.

No great difference is apparent when comparing the results of the two local surveys. The estimate of 22,000 pairs in Pembrokeshire which accompanied the 1984-88 survey was based on an average of 50 pairs per tetrad. This was a lower figure than the 60 pairs per tetrad used in the National Atlas of 1966–72, because an attempt was made to take into account the effects of the severe winter of 1982. The 1988-91 National Atlas used an average density of 44 pairs per tetrad for the UK. Since then the BBS has calculated  a 38% increase in Wales between the years 1994 and 2007. Applying this to the original Pembrokeshire estimate suggests that there were 30,000 pairs by the end of 2007. Although this is expressed as pairs, the social life of the Hedge Accentor is such that some territories can be occupied by one female mated to two males or by one male with more than one female. So perhaps the population should be regarded as the number of occupied territories rather than pairs.

Graham Rees

 

Fieldwork 2003-07 (based on 490 tetrads)

Red = breeding confirmed = 161

Orange = breeding probable = 273

Yellow = breeding possible = 11

Total tetrads in which registered = 445 (90.8%)

Wren - 2003-07

The estimate of 40,000 breeding pairs accompanying the 1984-88 survey was based on an estimated average density of 100 pairs per tetrad. The UK national average was assessed as being 120 pairs per tetrad. The lower estimated density in Pembrokeshire was based on the premise that the predominant pastureland would hold fewer birds than richer habitat to be found further east. However, subsequent findings have shown that density is high in areas of pasture, and the 1988-91 National Atlas, depicts maximum abundance in Pembrokeshire as a whole. It seems reasonably safe therefore to apply the UK value to the 2003-07 results, taking into account that the BBS indicates a 12% increase in Wales between 1994 and 2007. This results in an estimate of about 62,000 pairs breeding in the county. The population is expressed in pairs but Wrens are often polygamous, especially in prime habitat such as deciduous woodland.

Wrens can suffer high mortality during cold winters but there were unbroken mild winters during the years between the two local surveys, which would have been a major factor in the steady increase in their population.

Graham Rees

 

Fieldwork 2003-07 (based on 490 tetrads)

Red = breeding confirmed = 195

Orange = breeding probable = 265

Yellow = breeding possible = 7

Total tetrads in which registered = 467 (95.3%)

Dipper - 2003-07

The Pembrokeshire breeding population was estimated to be 70 – 140 pairs at the end of the 1984-88 survey, based on there being one to two pairs per occupied tetrad. No significant change was evident at the end of the 2003-07 survey when examining the “Confirmed + Probable breeding” categories. This suggests there has been no numerical change in the population. There was a 20% decrease in the number recorded in the “Possible breeding” category, which were birds recorded in the breeding season but where no evidence that they were nesting was found. The implications of this are not understood but see the account for Kingfisher.

Graham Rees

Fieldwork 2003-07 (based on 490 tetrads)

Red = breeding confirmed = 23

Orange = breeding probable = 15

Yellow = breeding possible = 17

Total tetrads in which registered = 55 (11.2%)

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%)

Swift - 2003-07

Swifts nest in cavities in buildings and in Pembrokeshire in the cliffs of the south coast.

Those nesting in cliffs apart, Swifts in Pembrokeshire are entirely reliant on buildings for nest sites. The amount of renovation that has taken place since the 1980’s has made an increasing number of buildings no longer accessible to Swifts and new constructions have also proved to be unsuitable. It could reasonably be expected, therefore, that the breeding population has decreased over the past 20 years. Comparing the confirmed and probable breeding registrations combined, indicates a 48% decrease between 1984-88 and 2003-07.  This is consistent with the BBS index showing a 47% decrease in Wales as a whole between 1994 and 2007. The possible breeding category was ignored when interpreting the results of both local surveys,

Swifts being such mobile birds when feeding, they can be seen almost anywhere without this providing any clue to their nest site. Although no good method of assessing population has been evolved on a county scale, an estimate was made at the end of the 1984-88 survey by noting how many were entering buildings at some reasonably well-watched colonies and using this as guidance. The result was a rough estimate of about 2,000 pairs. Applying the distribution decrease to this figure suggests there may have been less than 1,000 pairs by the end of 2007. However this assessment makes no allowance for any decrease occurring within the surviving distribution, something which has not been quantified. It could well be that the number breeding in Pembrokeshire has dipped below 1,000 pairs.

 Graham Rees

 

Fieldwork 2003-07 (based on 490 tetrads)

Red = breeding confirmed = 39

Orange = breeding probable = 13

Yellow = breeding possible = not included

Total tetrads in which registered = 52 (10.6%)

Collared Dove - 2003-07

Most people, whether they live in town or village, will be familiar with this pale buff dove with its striking dark collar and monotonous cooing song. Originally a bird of the Orient, it has expanded its range to eventually colonise Britain. It first nested in Pembrokeshire in 1961 and was widespread by the time of the 1984-88 survey. It has been found to have a close association with human habitation, occurring around farmsteads, small holdings and gardens but to be absent from more open countryside. Its flimsy nest is placed in trees, particularly conifers and it is able to breed all year long.

Comparison of the two survey results shows a 15% increase in distribution by the latter period. This compares with an 18% increase in Wales as a whole between 1984 and 2007 noted by the BBS. The estimated Pembrokeshire breeding population of 1,600 – 2,100 which accompanied the survey of 1984-88, was based on a range of six to eight pairs per occupied tetrad, which attempted to cater for higher densities in suburban areas than in isolated homesteads. The same situation prevailed during the 2003-07 survey, so applying the 15% increase to the earlier estimate suggests a breeding population in the range of 1,830 to 2,440 pairs in the county.

Graham Rees

Fieldwork 2003-07 (based on 490 tetrads)

Red = breeding confirmed = 69

Orange = breeding probable = 199

Yellow = breeding possible = 41

Total tetrads in which registered = 309 (63.1%)

Woodpigeon - 2003-07

It was estimated that there were about 10,000 pairs breeding in Pembrokeshire at the end of the 1984-88 survey. This was based on an average of 25 pairs per occupied tetrad. The 1988-91 National Atlas used an average of about 40 per tetrad for the UK as a whole. The highest concentrations were found in woodland and areas of arable farming, particularly where these habitats were found adjacent to each other.

Woodland and arable farmland makes up only a small proportion of Pembrokeshire which is largely a pastoral county. Considering also that many of the fields are bounded by hedgebanks with few suitable trees for nesting, makes it likely that Woodpigeon density is lower than the UK average. It is notable too that only a 4% increase in distribution was found between the two local surveys, 1984-88 and 2003 – 2007, compared to a 35% increase in Wales as a whole between 1994 and 2007 noted by the BBS. Using an estimated average of 26 pairs per tetrad it is thought that about 11,000 pairs were nesting in the county at the end of 2007.

Graham Rees

 

Fieldwork 2003-07 (based on 490 tetrads)

Red = breeding confirmed = 160

Orange = breeding probable = 235

Yellow = breeding possible = 40

Total tetrads in which registered = 435 (88.8%)

Stock Dove - 2003-07

The Stock Dove population of the UK was considered to be stable in the 1980’s, having recovered from a decline in the 1950’s and 1960’s caused by the effects of organo-chlorine seed dressings, used in arable farming, which were subsequently withdrawn. It is unlikely this had a big impact in Pembrokeshire which has long been dominated by pasture land. The chemicals did have an effect on Peregrines, the local population crashing in the 1950’s. Peregrines prey on many mobile birds, such as racing pigeons, which would have arrived in the county already affected, and the falcons being at the head of the food chain accumulated the chemicals with detrimental consequences. While the Peregrine population was low, Stock Doves expanded their range in the county, colonising the offshore islands from about 1975. However, as Peregrine numbers recovered, fewer Stock Doves nested on the islands and by the time of the 1984-88 survey had almost disappeared. They continued to nest on some of the mainland cliffs but the majority were thinly spread inland.

It was estimated that on average there were no more than two or three pairs per occupied tetrad, suggesting a county population of 300 – 500 pairs. The 2003-07 survey revealed a marked decrease in Stock Dove numbers, distribution contracting by 38%. This suggests that the Pembrokeshire breeding population lay in the range 180 -300 pairs by the end of 2007.

Graham Rees

 

Fieldwork 2003-07 (based on 490 tetrads)

Red = breeding confirmed = 11

Orange = breeding probable = 49

Yellow = breeding possible = 38

Total tetrads in which registered = 98 (20%)

Feral Pigeon - 2003-07

Feral Pigeons are domesticated birds that have escaped from captivity to breed in a wild state, as well as their descendents. Such domestic birds are derivatives from Rock Doves which have been selectively bred as racers, or to breed throughout the year when they were relied upon as a food resource. Selective breeding has resulted in a great variety of plumage patterns, including some which approximate to their Rock Dove ancestors. It is unlikely that any pure bred Rock Doves have survived in Pembrokeshire because of inter breeding with the numerically preponderant feral varieties. Feral Pigeons in Pembrokeshire nest on ledges in buildings, quarries and sea cliffs.

Comparing the distribution in 1984-88 with that of 2003-07 shows a 63% increase by the latter period. The number of registrations diminished along parts of the coast in the west and north but showed an increase inland, albeit with a considerable adjustment in localities. The increase accords with the findings of the BBS, which assessed a 69% increase in Wales as a whole between 1994 and 2007. The estimate made at the end of 1988 of 3,000 pairs in Pembrokeshire, attempted to allow for larger concentrations in towns than elsewhere. Assuming the estimate was realistic and applying a 63% increase, suggests that approaching 5,000 pairs were nesting in 2007. The reasons for the increase are not known but a diminished interest in maintaining lofts by pigeon racers, with a consequent release of birds, may have been a contributory factor.

Graham Rees

 

Fieldwork 2003-07 (based on 490 tetrads)

Red = breeding confirmed = 119

Orange = breeding probable = 74

Yellow = breeding possible = 40

Total tetrads in which registered = 233 (47.6%)

Moorhen - 2003-07

Normally retiring in nature, moorhens can become quite confiding in public areas, such as Pembroke Mill Ponds. Moorhens inhabit lowland fresh water places with well vegetated margins, which are essential for nesting. They sometimes use old nests of other birds, even when they are in trees.

A comparison of the two surveys indicates a 13% increase in distribution by the latter period. If this is applied to the estimate of 300 pairs accompanying the earlier survey, then there were probably about 340 pairs in 2007. The increase was probably due to irrigation reservoirs which were new and bare during the 1980’s now acquiring vegetation.

Graham Rees

Fieldwork 2003-07 (based on 490 tetrads)

Red = breeding confirmed = 86

Orange = breeding probable = 52

Yellow = breeding possible = 32

Total tetrads in which registered = 170 (34.7%)

Water Rail - 2003-07

This slender, long-billed crake with its cryptic brown and grey plumage broken by dark streaks, is more often heard than seen. It inhabits mainly fresh water lowland, boggy places with dense plant growth, making it difficult to see and providing concealment for its nest.

Bearing in mind how difficult detection of this species is, the survey results must be regarded as representing a minimum presence. The most striking difference in distribution change is the absence in the St David’s area indicated by the latter survey. There has been no obvious visible change, or loss or fragmentation, in the relevant habitat during the interval between surveys, suggesting apparent absence may not have been real. In that case it could be concluded that there has been no change in the county population level of about 20 pairs. A specialist census concentrating on this species might well be revealing and could lead to a reassessment of its breeding status in Pembrokeshire.

Graham Rees

  

Fieldwork 2003-07 (based on 490 tetrads)

Red = breeding confirmed = 1

Orange = breeding probable = 5

Yellow = breeding possible = 10

Total tetrads in which registered = 16 (3.3%)

Great Crested Grebe - 2003-07

Great crested grebes were first proved to have bred in Pembrokeshire when a pair incubated eggs at Llys-y-fran Reservoir in 1996, the nest later being predated. Although present there in following years, breeding was not proven again until 2004. A pair present with three juveniles in July 2002 was suggestive but at that date they could have come from elsewhere.

Single pairs occupied Rosebush Reservoir from 1995 onwards and were seen to have hatched a chick in 1997. They may well have attempted breeding there in each subsequent year, it being confirmed in 1999, 2002, 2004 and 2006.

Breeding was attempted at Heathfield Gravel Pit in 2005 but was unsuccessful.

Graham Rees