Wren – 2019 BBS

Troglodytes troglodytes – DRYW – Breeding resident

The wren is a pretty ubiquitous species across Pembrokeshire, it having been recorded in almost every tetrad in the 2003-07 atlas.  More than that, the BTO Atlas 2007-11 shows that Pembrokeshire is one of the most densely populated areas of the UK as far as wrens are concerned.

While it is basically a bird  of deciduous woodland, it is an adaptable species also common in scrub, pastoral farmland, villages, towns, and even coniferous woodland.  So, not surprisingly it is recorded in virtually every square covered by the Breeding Bird Survey in the county.

With less than 15 squares surveyed before 2002, the results could be expected to be a little erratic, while the apparent dip in the population in 2001 was the result of only two squares being surveyed during the foot-and-mouth outbreak.  Nevertheless, the population density seems to be increasing overall.

Like many small, but warm-blooded, creatures, the wren is susceptible to cold weather, so it should be expected that breeding populations will be reduced after severe winters.  The graph shows the short-term effects of cold conditions in 1995/96, 2009/10, 2010/11 and 2017/18.  These are evident on the Breeding Bird Survey index for both Britain and for Wales, yet in Pembrokeshire there is an unexplained dip in the summer before the 2017-18 winter and an increase afterwards. 

In the longer term, the population in Wales has increased by 9% between 1995-2018 (Harris et al. 2020), and in Pembrokeshire it is showing a similar trend.

Skokholm

While Skokholm isn’t part of the BBS network, all the breeding birds there are monitored intensively each year.

Wrens first bred on the island in 1988, and numbers have been increasing ever since.  In 2018, 63 territorial males were mapped.  Perhaps surprisingly, given the snow and freezing conditions prevalent during February and March that year, the total was five up on that of previous year and two up on the 2016 Skokholm record.  The reason for this substantial increase in the number of territorial males is unclear.

Annie Haycock (BBS & WeBS local organiser)

References:

BALMER D, GILLINGS S, CAFFREY B, SWANN B, DOWNIE I, FULLER R. 2014. Bird Atlas 2007-11: The Breeding and Wintering Birds of Britain and Ireland.  HarperCollins.  UK

BROWN R & EAGLE G, 2018 Skokholm Annual Report. Wildlife Trust for South and West Wales.

HARRIS S J, MASSIMIMINO D, EASTON M A, GILLINGS S, NOBLE D G, BALMER D E, PEARCE-HIGGINS J W & WOODCOCK P. 2019. The Breeding Bird Survey 2018. BTO Research Report 717. British Trust for Ornithology, Thetford.

More about the Wren in Pembrokeshire

Wren – 2003-07 breeding

Troglodytes troglodytes – DRYW – Breeding resident

Comparison with previous atlas:

1984-882003-07
Breeding confirmed210195
Breeding probable230265
Breeding possible87
No of tetrads occupied448 (of 478)467 (of 490)
Percentage of tetrads93.7%95.3%

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. Pembrokeshire County Bird Recorder 1981-2007

More about the Wren in Pembrokeshire

Wren – 1994

Troglodytes troglodytes – DRYW – Breeding resident

1984-88
Breeding confirmed210
Breeding probable230
Breeding possible8
No of tetrads occupied448 (of 478)
Percentage of tetrads93.7%

A common resident to Mathew (1894) and Lockley et al. (1949). Today Wrens nest everywhere in Pembrokeshire apart from the mountain tops and the smallest offshore islets such as Grassholm and the Smalls (see map). At an estimated 100 pairs per tetrad the population probably totalled about 40,000 pairs during the 1984-1988 Breeding Birds Survey.

Wrens suffer high mortality during severe winters, that of 1963 being particularly devastating. Numbers recover quickly in subsequent breeding seasons provided no further cold winters intervene. Wrens are predominantly woodland birds in Pembroke­shire during times of low population, suggesting that this is their preferred habitat and that other places are occupied as increasing numbers enforce expansion; for instance, Skokholm was colonised for the first time in 1987 when the mainland population was high.

Donovan J.W. & Rees G.H, 1994, Birds of Pembrokeshire

More about the Wren in Pembrokeshire

Wren – 1990s winter

Troglodytes troglodytes – DRYW – Breeding resident

The BTO winter atlas showed that Wrens were present in the majority of 10km squares during the winters of 1981-82, 1982-82 and 1983-84.

The darker the colour, the higher the relative total count for each 10km square.  The darkest blue represents over 25 birds seen in a day

Data collected by volunteers for the BTO. Lack, P. 1986 Atlas of wintering birds in Britain and Ireland. T & A.D. Poyser.

More about the Wren in Pembrokeshire

Wren – 1894

Troglodytes parvulus – A common resident

Very abundant in our grounds, where we used to detect numerous nests. One we found was lined with the feathers of a Sparrow Hawk’s breast, so the birds had evidently availed themselves of one that had been shot in an adjoining plantation. A pair of Wrens passed the whole of one severe winter in one of our green-houses where they seem to have found plenty of food.

Mathew M.A. 1894, Birds of Pembrokeshire and its Islands

More about the Wren in Pembrokeshire

Wren

Troglodytes troglodytes – DRYW – Breeding resident

Wren – 2019 BBS

Troglodytes troglodytes – DRYW – Breeding resident The wren is a pretty ubiquitous species across Pembrokeshire, it having been recorded in almost every tetrad in the 2003-07 atlas.  More than that, the BTO Atlas 2007-11 shows that Pembrokeshire is one of the most densely populated areas of the UK as far as wrens are concerned. […]

Wren – 2003-07 breeding

Troglodytes troglodytes – DRYW – Breeding resident Comparison with previous atlas: 1984-88 2003-07 Breeding confirmed 210 195 Breeding probable 230 265 Breeding possible 8 7 No of tetrads occupied 448 (of 478) 467 (of 490) Percentage of tetrads 93.7% 95.3% The estimate of 40,000 breeding pairs accompanying the 1984-88 survey was based on an estimated […]

Wren – 1994

Troglodytes troglodytes – DRYW – Breeding resident 1984-88 Breeding confirmed 210 Breeding probable 230 Breeding possible 8 No of tetrads occupied 448 (of 478) Percentage of tetrads 93.7% A common resident to Mathew (1894) and Lockley et al. (1949). Today Wrens nest everywhere in Pembrokeshire apart from the mountain tops and the smallest offshore islets such as […]

Wren – 1990s winter

Troglodytes troglodytes – DRYW – Breeding resident The BTO winter atlas showed that Wrens were present in the majority of 10km squares during the winters of 1981-82, 1982-82 and 1983-84. The darker the colour, the higher the relative total count for each 10km square.  The darkest blue represents over 25 birds seen in a day More about […]

Wren – 1968-72 breeding

Red = breeding confirmed Orange = breeding probable Yellow = breeding possible More about the Wren in Pembrokeshire

Wren – 1949

Species account from the Birds of Pembrokeshire, 1949, by Lockley, Ingram and Salmon.

Wren – 1894

Troglodytes parvulus – A common resident Very abundant in our grounds, where we used to detect numerous nests. One we found was lined with the feathers of a Sparrow Hawk’s breast, so the birds had evidently availed themselves of one that had been shot in an adjoining plantation. A pair of Wrens passed the whole of one severe winter in […]