Welsh Journals

FIELD NOTES BIRDS Bird records should be sent to County Bird Recorders but accounts of interesting occurrences, changes in population, unusual behaviour, etc., should be sent to F. W. Donovan, The Burren, Dingle Lane, Crundale, Haverfordwest. OPPORTUNATE HERRING GULLS On 20 May 1973 I spent some hours on the cliff path at St. Davids where the wind was blowing off-land. Large gatherings of ihsects were noted in the sheltered cliff areas with the result that herbage, bare rocks, tide exposed rocks and the lee of Penberi Rock itself were literally covered with legions of flies identified as St. Mark's Fly (Bibio marci) and Fever Fly (Dilophus febrilis). The calm sea surface close inshore was also dotted with insects. Before long it was noticeable that Herring Gulls were taking these flies from the sea-swimming amongst the drowning insects and pick- ing them off the surface. The Gulls were also ranging in parties on the bare rocks including Penberi and taking the insects with evident enthusiasm. It seems that all is grist to the mill for these very versatile birds: small wonder they are so successful. J.W.D. DECLINE IN SEDGE WARBLERS? In recent years, a visit to Rosebush Reservoir in Pembrokeshire has yielded at least three occupied territories for this species. In June 1973 none appeared present on three visits and it seems that breeding has not occurred at this location. Grasshopper Warblers were present in usual numbers. Several warbler species have suffered population fluctuations lately-the Whitethroat seems to be making some recovery from its recent population lows. One hopes the Sedge Warbler will also recover, if in fact it has really declined? J.W.D. GREAT NORTHERN DIVER AND GREAT CRESTED GREBE On 13 December 1972 a Great Crested Grebe and a Great Northern Diver were fishing in Fishguard Harbour. On one occasion the Diver came to the surface holding a silvery fish about 5 inches long across its bill. While it was manipulating the fish the Great Crested Grebe appeared close alongside it, as though intending to attack. The Grebe submerged and came up on the other side of the Diver with its head and neck only above water. It dived again and surfaced behind the Diver for a moment, went down to reappear