Raven - 1994

Breeding resident

Ravens have increased in Pembrokeshire since the time of Mathew (1894), who thought that 20 pairs nested. By 1949, Lockley et al. were able to note that the population had grown to not less than 80 pairs, 60 of them on the coast and islands.

A reasonably accurate assessment of the present population can be made following the fieldwork of the Breeding Birds Survey of 1984-1988. Ravens were found breeding on the offshore islands and the mainland cliffs and on crags and in trees in most areas inland. On the islands, 12 pairs were reported breeding, with 65 pairs around the outer coast. The inland population has been estimated by omitting the 'present' category from the map, as such records could represent wandering non- breeders or foraging adults from nests in adjoining tetrads. The resultant map plot suggests that about 60 pairs breed inland, making a total county population of about 140 pairs.

They have a tendency to flock after the breeding season, although many individuals seem not to become involved and some breeding territories remain occupied throughout the year. Flocks of up to 80 have been noted on Skomer in September (when fledgling Manx Shearwaters are probably the attraction) and of up to 250 at Dudwell from August (attracted by discarded offal from the slaughterhouse). The Skomer flock generally disperses in October but the Dudwell gathering persists longer and up to 170 have been recorded there into April ( these are presumably non‑breeding birds). Ravens also form communal roosts during the winter, the sites being subject to periodic change. Up to 150 were noted roosting at Walwyn's Castle in 1954 and up to 263 at Roch in 1964, but most roosts feature 30-50 birds.

They are highly mobile birds and are seen passing over all parts of the county. Some may be wanderers from outside Pembrokeshire, for there is evidence to confirm this: nestlings ringed at Skokholm have twice been recovered in north Wales, which suggests some degree of interchange.

Young birds from the quarry at Goodwick Moor used to be exported to replenish the population at the Tower of London.

            

Fieldwork 1984-88 (based on 478 tetrads) 

Red = breeding confirmed = 91

Orange = breeding probable = 42

Total tetrads in which registered = 133 (27.8%)

Inland breeding tetrads= 57 (42.9% of breedng tetrads)

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