Turdus iliacus – COCH DAN-ADEN – Winter visitor and passage migrant. Not recorded in July and August
Mathew (1894) and Lockley et al. (1949) agreed that the Redwing was a common winter visitor and that cold weather brought great numbers to Pembrokeshire.
Redwings normally arrive in Pembrokeshire from early October, the earliest record being of one at Skokholm on 11 September 1976. Thousands pour through until early December, flocks often stopping off to feed in the fields and on hedgerow berries. Some falls involve large groups, such as about 1,500 at Skokholm on 28 October 1964. Far greater numbers appear to pass at night judging by the frequency of calls overhead, and they have featured strongly at lighthouse attractions at the Smalls, South Bishop and Strumble Head. They have been noted departing out to sea towards Ireland in the early mornings, and one ringed at Skokholm in October 1964 and recovered in France in December the same year illustrates through passage to the south. Icelandic Redwings T. i. coburni, which are longer winged and darker than the Eurasian race T. i. iliacus (Svennson 1992), have been identified in the hand at Skokholm.
The number wintering varies with the weather and the berry crop. Severe weather to the east brings large influxes, many thousands of birds pouring into the coastal region. These immigrants may quickly retreat following a thaw only to return if the weather turns cold again. When cold weather actually grips Pembrokeshire many die, Lockley et al. recording thousands perishing in such circumstances. This scale of mortality has not been recorded since, although 245 were found dead at Skomer in the arctic winter of 1962 (Harris 1962) and many died at Stackpole in 1985, some weighing as little as 50 grams, compared with a normal weight of over 70 grams. They largely vacated Pembrokeshire in the winter of 1986 when, uncharacteristically, several weeks of frost occurred.
There is a distinct return passage from late February to early April, when Redwings are again heard passing at night and seen at the lighthouses. Most have departed by mid-April, but stragglers have occurred until 6 May, and singles have been noted at Skokholm on 13 June 1939 and 18 June 1979.
HARRIS, M.P. 1962. Weights from five hundred birds found dead on Skomer Island in January 1962. British Birds 55: 97-103
SVENSSON , L. 1992 (fourth edition). Identification guide to European passerines. Stockholm, Svensson.