Jackdaw - 1949 status

Corvus mondedula spermolegus

Common resident, except at Skokholm and Grassholm, where only a spring migrat at same time as Rook.  Breeds on cliffs and in ruins, etc, inland.  A writer in the Field, 2 June, 1860, noted that it bred in burrows at Skomer; it still dows this - in sea-bird burrows on the edge of the cliffs.

R.M.Lockley, G.C.S.Ingram, H.M.Salmon, 1949, The Birds of Pembrokeshire, The West Wales Field Society

Jackdaw - 2003-07

At the close of the survey of 1984-88 it was realized that the only assessment of breeding Jackdaw numbers anywhere in the county came from the islands of Skokholm and Skomer. An estimate of the population for the whole county had not previously been attempted. An assessment that an average of 20–30 pairs per tetrad was possible was used, postulating that there were 9,000–13,000 pairs breeding in Pembrokeshire. The 1988-91 National Atlas calculated an average density across the UK which was a little lower than the lowest value used for the initial local survey. The National Atlas also assessed relative abundance, the map of which showed Pembrokeshire at maximum. Making an adjustment to allow for this density suggests that the original estimate of 20 pairs per tetrad in the county was realistic. The BBS then indicated a 36%increase in Wales as whole between 1994 and 2007. No evidence was found that such an increase had taken place in Pembrokeshire but some sign that it has not.

Over the years there has been a 33% decline in the number breeding at Skokholm and a 66% decrease at Skomer. Studies on the islands have shown very low productivity even during times when breeding numbers increased there, meaning birds were being recruited from the mainland. The declining numbers which followed suggests such recruitment ceased, probably because there was no longer a surplus of birds on the mainland. With this in mind it seems best to be cautious and consider that county numbers had not increased. In this case the breeding population in Pembrokeshire at the end of 2007 was thought to have been about 9,000 pairs.

Graham Rees

 

Fieldwork 2003-07 (based on 490 tetrads) 

Red = breeding confirmed = 361

Orange = breeding probable = 18

Yellow = breeding possible = 58

Total tetrads in which registered = 437 (89.2%)

Jackdaw - 1994

Breeding resident

A common resident according to Mathew (1894) and Lockley eta (1949), the Jackdaw is probably the most versatile of Pembrokeshire's birds, for it has learnt to exploit just about every niche in the county, nesting in quarries, on crags, in trees, in buildings and other man-made structures, in the sea cliffs of the mainland and on the larger offshore islands.

They were noted breeding in burrows at Skomer as early as 1860 (Lockley et al.). Wintle (1924) recorded them nesting in fair numbers on Caldey in 1924 and Lloyd found that they were an established breeding bird on Ramsey in 1927.  Skokholm was colonised in 1965, with numbers building to a peak of 60 pairs between 1975 and 1978 but declining to only five pairs by 1992.  At Skomer they increased from 20 pairs between 1946 and 1958 to 200-250 pairs in 1961, and the 1991 census fround 248 pairs.  Colony size elsewhere varies widely, but an estimated average density of 20-30 pairs per tetrad would mean a total breeding population of 9,000-13,000 pairs.

They form large communal roosts outside the breeding season, that at St David's Cathedral being notable for creating so much noise during their evening assembly that it eclipses the best efforts of the choir!

Despite numerous records of Jackdaws flying about over the sea we have found no evidence to confirm immigration of emigration.

Fieldwork 1984-88 (based on 478 tetrads) 

Red = breeding confirmed = 356

Orange = breeding probable = 23

Yellow = breeding possible = 70

Total tetrads in which registered = 449 (93.9%)

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

Jackdaw - 1970s breeding

Red = breeding confirmed

Orange = breeding probable

Yellow = breeding possible

Jackdaw - 1980s winter atlas

The BTO winter atlas showed that Jackdaws were present in most 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 400 birds.

The map plot reflects winter flocking in the coastal plain and consequent large roosts.

Graham Rees 

Jackdaw - 1894

Species account from M Mathew, 1894, "The Birds of Pembrokeshire and its islands"

Click to read more ...