The Marbled Duck, first discovered by Steve Fisher at Stanwick GP’s main lake on 13th January and still present today, promptly disappeared almost immediately until rediscovery on 19th February. Or did it? With persistent inclement weather, rising water levels and less than ideal viewing conditions, it appears it may have been there, somewhere, all the time as it is now known to hide among the overgrown islands on the western side of the lake.
Despite being recorded sporadically in the UK, this species remains on category D of the British List as it is common in captivity but an established pattern of records suggests it is likely that some wild individuals occur. Vagrants have been recorded in Northern Spain and in the Camargue in Southern France with most French records in August-September and a secondary spring peak in April. The pattern of British records also reflects this and Marbled Duck has been accepted as a genuine vagrant in the Netherlands.
Pouring at least some cold water on the vagrancy hypothesis, analysis of the stable-hydrogen isotope content of feathers taken from a first-winter shot in Essex on 1st September 2007 suggested that the bird originated from outside of the normal breeding range of the species and was most likely to have been of captive origin (see British Birds).
Although thought to be in decline, the global population is estimated at c.50,000-55,000 individuals, based on estimates of 3,000-5,000 in the west Mediterranean and West Africa, 1,000 in the east Mediterranean 5,000 in south Asia, and at least 44,000 individuals counted in Iraq in 2010 according to BirdLife International.
There has been one previous record of Marbled Duck in the county – coincidentally at Stanwick GP, on 29th June to 3rd July 1990.