There are three forms of Lesser Black-backed Gull reportedly occurring in the UK; Baltic Gull - Larus fuscus fuscus originating from the Baltic Sea and eastern Scandinavia and has a mantle that is jet black; Continental Lesser Black-backed Gull - L. f. intermedius  from Denmark, The Netherlands and Norway who's mantle is sooty black and Lesser Black-backed Gull - L. f. graellsii from the British Isles, Iceland and northern France and has a dark grey mantle. These characteristics are light affected and sometimes marginal, clearly the whole suite of identification factors need careful assessment.

There have been around ten Baltic Gulls reported from S. Gloucestershire, they are;

1978: (5)

Five individuals of the Scandinavian form 'fuscus' were reported from Littleton-on-Severn on March 31st.

1979: (2)

Two dark mantled birds showing characteristics of the Scandinavian form 'fuscus' (possibly 'intermedius') were reported from Rangeworthy on March 10th.

1981: (2)

Sometime in April two birds were reported from Oldbury-on-Severn showing characteristics of the all dark Scandinavian form 'fuscus' (or possibly 'intermedius').