There was a single Common Tern, Sterna hirundo, fishing the gravel pits stylishly and successfully! In the first picture, where the bird is dark against the lightness of the sky, I think I can see the light (sometimes called translucent) panel in the middle of the wing that is said to help to distinguish this bird from the Arctic Tern, Sterna paradisaea, where much more of the wing is said to be translucent. That I don't find this convincing says rather more about my very poor skills as a birdwatcher than it does about Tern field characteristics!
Rather clearer here are the black tip to the otherwise comparitively light red bill, and the not excessively long tail streamers. It is also easier to see the black outer webs on primaries P10 - P5.
Above I think I would only just agree that the dark trailing edge to the wings in the outer primary section bleeds well forward into the rest of the wing but on the lower side there is a limited and sharper dark trailing edge. This does not taper off inwards. A limited dark trailing edge not bleeding forwards to form a dusky wedge on the upper side is said to be more characteristic of the Arctic Tern, and the dark trailing edge on the underside should taper off inwards in that species.
The bird seemed reasonably successful and the one time I followed a dive a small fish was apparently fairly easily taken, as shown below. Common Terns are said to be more likely to dive directly rather than hover briefly before diving as Arctic Terns are generally said to do (Bird Forum), and this bird seemed to halt, twist (bank sharply) and dive almost back on itself but nearly vertically into the water, perhaps flattening out a bit as it hit the water surface. However BWP claims that they do hover but less rapidly than the Arctic. It would be interesting to follow the sequence more exactly with high speed shooting, or even video.
Common Terns are flexible feeders but generally are dive-plunge feeders, often but not always submerging 20 - 30 cm. They also surface feed or even plunge from perches. The main prey is fish, but the diet also includes shrimps and other crustacea as well as insects perhaps taken from the surface. This particular bird just seemed to be plunge-diving for fish!
A more important point though is why hasn't it eaten the fish instantly, as BWP claims it should have done.. Where is it taking it? To a partner or a nest? Or is this bird just passing through, and just being slow to eat its catch?
Perhaps its not too surprising to see an individual inland, but its difficult to know if this is just migrating through the area, or perhaps specifically looking for an inland site to breed upon. This could be a late migrating bird, just arrived following the long journey North from the wintering grounds of West Africa. What a pity there are no nesting rafts on these pits. Once a pair has chosen a nest site they may return to the same site year after year (17 years is apparently the current record until one of the pair failed to return).
After fledging and learning to fish on their own, juveniles may start to move South either in family groups or small flocks of juveniles only. They may trek backwards and forwards for anything up to 3-4 years before first breeding, but sometimes breeding can start at 2 years old. When they are old enough to breed, they may breed in the colony they were born in, or nearby.
Mates do not seem to associate closely in the winter quarters, but arrive at the nest site paired up, having found each other perhaps in the winter quarters prior to departure, on passage, or in and around the colony. They arrive initially at a roost close to the colony and already paired birds can be recognised by roosting closer to each other than the average.
Once the next territory is established it is used for courtship, copulation, pair-bonding, nesting and initially (up to 23 days) concealing and feeding the young.
Population is about 15,000 in UK, fairly stable and the smaller inland population appears to be growing. This pattern not repeated consistently across Europe.
Rather clearer here are the black tip to the otherwise comparitively light red bill, and the not excessively long tail streamers. It is also easier to see the black outer webs on primaries P10 - P5.
Above I think I would only just agree that the dark trailing edge to the wings in the outer primary section bleeds well forward into the rest of the wing but on the lower side there is a limited and sharper dark trailing edge. This does not taper off inwards. A limited dark trailing edge not bleeding forwards to form a dusky wedge on the upper side is said to be more characteristic of the Arctic Tern, and the dark trailing edge on the underside should taper off inwards in that species.
The bird seemed reasonably successful and the one time I followed a dive a small fish was apparently fairly easily taken, as shown below. Common Terns are said to be more likely to dive directly rather than hover briefly before diving as Arctic Terns are generally said to do (Bird Forum), and this bird seemed to halt, twist (bank sharply) and dive almost back on itself but nearly vertically into the water, perhaps flattening out a bit as it hit the water surface. However BWP claims that they do hover but less rapidly than the Arctic. It would be interesting to follow the sequence more exactly with high speed shooting, or even video.
Common Terns are flexible feeders but generally are dive-plunge feeders, often but not always submerging 20 - 30 cm. They also surface feed or even plunge from perches. The main prey is fish, but the diet also includes shrimps and other crustacea as well as insects perhaps taken from the surface. This particular bird just seemed to be plunge-diving for fish!
A more important point though is why hasn't it eaten the fish instantly, as BWP claims it should have done.. Where is it taking it? To a partner or a nest? Or is this bird just passing through, and just being slow to eat its catch?
Perhaps its not too surprising to see an individual inland, but its difficult to know if this is just migrating through the area, or perhaps specifically looking for an inland site to breed upon. This could be a late migrating bird, just arrived following the long journey North from the wintering grounds of West Africa. What a pity there are no nesting rafts on these pits. Once a pair has chosen a nest site they may return to the same site year after year (17 years is apparently the current record until one of the pair failed to return).
After fledging and learning to fish on their own, juveniles may start to move South either in family groups or small flocks of juveniles only. They may trek backwards and forwards for anything up to 3-4 years before first breeding, but sometimes breeding can start at 2 years old. When they are old enough to breed, they may breed in the colony they were born in, or nearby.
Mates do not seem to associate closely in the winter quarters, but arrive at the nest site paired up, having found each other perhaps in the winter quarters prior to departure, on passage, or in and around the colony. They arrive initially at a roost close to the colony and already paired birds can be recognised by roosting closer to each other than the average.
Once the next territory is established it is used for courtship, copulation, pair-bonding, nesting and initially (up to 23 days) concealing and feeding the young.
Population is about 15,000 in UK, fairly stable and the smaller inland population appears to be growing. This pattern not repeated consistently across Europe.
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