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Tuesday
Dec272011

Chough - 1994

Breeding resident

Mathew (1894) thought the Chough common all around the coast from Tenby to Dinas between 1840 and 1850. He noted nesting in the ruins of the Bishop's Palace at St David's and in abundance at Manorbier Castle in 1857. However, by 1894 he considered they were fast becoming scarce.

Lockley et al. (1949) considered the Pembrokeshire breeding population to have been static at around 30 to 36 pairs for a period of at least 50 years. They also calculated that this was probably the population level during Mathew's time.

During the 1963 BTO Chough survey 33-36 pairs were found breeding (Rolfe 1966), but the coverage of the coastline was incomplete, and the hard winters of 1962 and 1963 had probably reduced the population.  A repeat survey conducted in 1971 by the Dyfed Wildlife Trust covered more ground, with just a few gaps, and found 46 pairs (Donovan 1972). The RSPB-organised Chough survey of 1982 achieved complete coverage and located 51 pairs, of which 24 produced 74 fledged birds (Bullock, Drewett and Mickleburgh 1985). Complete coverage was also achieved with the 1992 census when 58 pairs were found plus 15 non-breeding birds.

Our interpretation of the various census results is that the population has probably been fairly stable throughout the century, though severe winters have caused temporary decreases. Whether the population will remain stable is currently concerning the conservation bodies. Disturbance from cliff-path walkers, the activities of rock climbers and possibly egg collectors, as well as changes in land use practices, may all have an impact on Choughs. Donovan (1972) drew attention to the importance of grazing animals for the availability of food, especially dung beetles, in terrain where they would be accessible to Choughs. An international workshop held at Orielton in November 1988 concluded that these conditions could best be ensured by the maintenance of traditional mixed farming, providing a mosaic of habitat types (Bignal and Curtis 1989). Meyer (1989) pointed out the additional advantage of disturbed substrates, such as areas 'poached' by cattle and vehicle tracks, which improved accessibility to Choughs' invertebrate food. He also highlighted the importance of walls and hedgebanks where these had not been covered in long vegetation.

Choughs prefer natural nest sites in Pembrokeshire, the only recent man-made structure utilised being a derelict aircraft hanger at Kete in 1979, which has since been demolished. Pembrokeshire Choughs do not normally penetrate inland by more than a few kilometres, although one was recorded at Crymych in March 1972.

Nestlings ringed at Bardsey have been found in Pembrokeshire on three occasions, one possibly having joined the local breeding population at Cemaes Head in 1987. During the winter of 1992/93 several juveniles were colour ringed on the south-west peninsula, and it will be interesting to see how far they travel before settling to breed. Regular interchange of individuals within the Irish Sea population would ensure gene flow and healthy birds. 

 

 

Fieldwork 1984-88 (based on 478 tetrads)

Red = Confirmed breeding = 40

Orange = Probable breeding = 9

Yellow = Possible breeding = 17

Total tetrads in which registered = 66 (13.8%) 

 

 

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

 

 

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