We never get to see Little Terns during the winter period in the UK, as they've all gone on their holibobs to seek a perpetual summer. They undergo a moult on migration and wintering grounds which sees them look quite different for much of this time. A recent trip to Thailand provided an opportunity to study the birds in this alternate plumage, at a site called Pak Thale. Now the main reason people visit this site, a set of salt-pans fronting on to the Bay of Bangkok, is to see the very rare and unique Spoon-billed Sandpiper (imagine a Dunlin with a kitchen utensil for a beak!) but I got slightly distracted by the presence of a whopping 1200 Little Terns roosting on the bunds. Thankfully a few flew closer and allowed photographs to be taken.
The main differences were in the beak, legs and head-pattern. The beak was completely black (mostly yellow in summer), the legs were dull orange (bright orange in summer) and the black on the head was restricted to a mask which stretched from the eyes to the back of the head with the rest of the cap white (all black in summer). These features combined make the birds look quite different to what we are used to seeing at Gronant and indeed initially it took me a moment to realise these were in fact Little Terns, the light-bulb eventually went off in my head due to them being tiny!