May 21st

Sandwich tern – all head, black front of end of the wing, yellow bill tip

Common tern – wings in middle, dirty wing and red bill with black tip

Arctic tern – all tail (no neck), neat black line on back of wing and all dark red bill

Now is a great time to see three species of tern at close quarters at Fife Ness. At high tide all three species are roosting on the rocks right up against the shore. I was able to approach to 20 meters without them responding and through a telescope I could see the landscape reflected in their eyes. The three tern species that we have around Crail during the summer – the ones that you are likely to see any day between May and October – are sandwich, common and arctic. At first glance they look similar – white gull things with black caps and thin pointed wings. To be able to identify them easily you need a few tips. Now the field guides will tell you about differences in bill colour but when a tern is shooting past Roome Bay at 40 km an hour this doesn’t help you very much. The trick is to look at their proportions – the apparent position of the wings on the body and consequently how much neck, head and bill are in front of the wings and how much body and tail are behind them. In flight, sandwich terns have wings that look closer to the back of their body and so look big headed like a pterodactyl; common terns have wings in the middle of their body so look evenly balanced and gull like  and arctic terns have wings that look closer to the front of the body so they look neckless. So that’s sandwich all head, common terns even and arctic terns all tail. These characters work best on an average or distant flight view – which is what most people get, especially if you haven’t got a pair of binoculars with you at the time. As the terns get closer I find these structural cues get less useful. First, basic impressions work best. Up close I will use the wing pattern: arctic have pure white wings with a neat black line underneath the wing tips forming the trailing edge; common have dirtier looking wings with a wedge of greyish black in the middle of the tips and a scruffy black trailing edge underneath and sandwich terns have the front edge of the wing blackish. And of course if you really get close the bill colour will do: yellow tip for sandwich, blood red for arctic and red with a black tip for common. It’s good to know these features because each of the terns has a different story – each species astonishingly flight capable and here for two or three months before moving on, in the case of the arctics, to literally the other end of the planet. Today Fife Ness felt a bit like Shetland – arctic terns everywhere and lots of noisy interactions. They won’t breed here because it is a bit too disturbed but the May Island has all three. If you visit the May when the terns are breeding then you will get views close enough to see their bills and you may find out exactly why arctic tern’s bills are the colour they are…

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