Willow Warbler – 1949

Phylloscopus trochilus trochilus

Common summer visitor, and abundant passage migrant, arrives last week in March.

He also mentions, under the section of the book on Land-Birds:

The first Willow-Warblers are trapped at Skokholm during the last week of March.  This is one of the largest small bird migrations in Pembrokeshire, and for the whole month between mid-April and mid-May there are days when the county swarms with these charming singers.

R.M.Lockley, G.C.S.Ingram, H.M.Salmon, 1949, The Birds of Pembrokeshire, The West Wales Field Society

More about the Willow Warbler in Pembrokeshire