Prunella modularis – LLWYD Y GWRYCH – Breeding resident
|No of tetrads occupied||434 (of 478)|
|Percentage of tetrads||90.8%|
A common resident (as it was for Mathew 1894 and Lockley et al. (1949) the Hedge Sparrow is absent as a breeding bird on the mountain tops and smallest offshore islands. At an estimated average density of 50 pairs per tetrad, there were probably 22,000 pairs during the Breeding Birds Survey of 1984-1988.
Numbers are depleted in severe winters but they are capable of steady recovery in subsequent breeding seasons. Island breeders, and those which inhabit exposed headlands, are noticeably reduced or even wiped out during hard weather but are replaced as the general population expands again.
Peaks in numbers are detected at Skomer in spring and autumn, suggesting migration, but the only confirmed movement was of a nestling ringed on Skokholm in July 1970 and recovered at Dale in November 1970.