Corvus corone
Breeding resident.
The Carrion Crow was assessed as common and widespread in Pembrokeshire by Mathew (1894), Lockley et al (1949) and Donovan and Rees (1994). They were persecuted by gamekeepers during Mathew’s time, a hint of the scale being the record of 134 killed on the Cawdor estate in 1821. This continued into the Lockley et al era, an example being 150 counted on a gibbet at Slebech in 1930. Such carnage diminished during the two World Wars when many gamekeepers were recruited to the armed services. Control measures are still attempted but on a small and localised scale, so they are now unmolested over much of their county range.
Nesting in trees, on old buildings and cliff ledges, the Carrion Crow has been found breeding all over the county, including the major offshore islands. Its breeding distribution was plotted in 1984 – 88 by a survey using tetrads as a grid and this was repeated in 2003 – 07.
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Breeding surveys
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1984 – 88
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2003 – 07
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Total tetrads where found
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459
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453
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Confirmed breeding
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390
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354
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Probable breeding
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22
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51
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Possible breeding
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47
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48
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An estimate of the breeding population was attempted following the survey of 1984 – 88, which was based on the distances between nests in a small number of random localities. With no other information available at the time, this was used to calculate a county total breeding population of 18,000 – 21,000 pairs. With the benefit of hindsight this is now considered to be an inflated total. The BTO’s New Atlas of 1988 – 91 showed Pembrokeshire contained Carrion Crows at maximum abundance and if their UK average density is used as an adjustment, a county population of about 10,000 pairs results, which seems more realistic. The 2003 – 07 survey found no marked difference in distribution from the 1984 – 88 survey, so there was probably no change in the size of the breeding population.
Being a successful breeder the Carrion Crow produces a surplus component to its population, comprised of immature birds that are too young to breed or adults which cannot find a vacant breeding territory. In places these form flocks which have been most noticeable on parts of the estuaries such as Fowborough and the Gann. This “reservoir” enables territories made vacant by various means, like shooting, to be recolonised.
There are several records of Carrion Crows flying in off or out to sea at headlands and islands, as far out as The Smalls, but the only concrete evidence of migration was of a nestling ringed on Bardsey Island which was recovered in north Pembrokeshire.
Graham Rees.
(Covers records up to and including 2010)
Saturday, December 14, 2019 at 6:00PM