Mysterious large gulls

Heysham Obs
A (very) routine day, with a missed opportunity for some reasonable early morning seawatching, was rudely interrupted by a late afternoon message concerning a 1st W American Herring Gull and (ad?) Yellow-legged Gull which were seen in Heysham Harbour about 1315hrs (the AHG flew towards the outfalls). This is a copy of what I have posted on the LDBWS site:

Before the speculation starts................
a) This bird was reported by person(s) unknown to a bird information source - lets choose the words carefully - which was not one of the usual ones used by inexperienced birders. The same report also included a Yellow-legged Gull

b) The immature large gulls around Heysham have not been checked thoroughly recently - they are also scattered all over on rooftops, mainly on the old Fishers corrugated roof

c) The first known check was some 2-3 hours after the report by which time the tide had dropped. This concentrated some gulls on the outfalls and Power Station intake - the bird was not with them - but also scattered many far and wide on distant skeers off Heysham etc.

d) Therefore I would not dismiss this record (or the YLG) out of hand

e) I personally have no time to properly search tomorrow = working day (or this evening after typing this - I had to be in High Bentham by 1830hrs, therefore had to leave the site).

Offshore
A 30 minute seawatch was carried out between 0925 and 0955 = too late as the weather cleared and a further short period from a visiting birder around lunchtime:

Gannet: c15 out
Fulmar: 1, possibly 2 out

Wooden jetty/harbour
Black Guillemot - two either on the water below or sitting on the middle section of the wooden jetty
Shag - a 1st W unable to lift itself properly off the water made its way out of the harbour and 'crawled' on to the lower stanchions of the wooden jetty to dry its wings. The secondaries appeared to be 'matted', hopefully not an encounter with a film of diesel or similar. Later it or the other recently seen 1st W was sat on the top tier of the jetty with the Cormorants

Elsewhere
Silent Wood Warbler still visible in treetops around Tower Lodge, Trough of Bowland. Cuckoo at Aldcliffe unusual