I have always been intrigued as to how the Caspian's Tern distribution seems to be mainly around South East Europe and Central Asia and on top of that North America?
Is it a species that has colonised North America?
It's all the way down to Southern Africa as well, other species occur on both side of the Atlantic, White-chinned Petrel for example.
Is it a species that has colonised North America?
Sorry, I'm not following what you mean: White-chinned Petrel occurs only in the Southern Oceans (except for the odd bird...).
Well, there are quite a few around the Falkland Islands (I even remember catching them by hand overnight assisting a ringer on Kidney Island in 1987) which is generally held to be in the South Atlantic on the West side: and they can also be seen off Namibia which is on the other side of the same ocean. There is more to the Atlantic than the bit between Europe and the USA.
John
Sorry, I didn't understand what Andy meant. Both sides of the Atlantic meant to me North and South, not east and west (apologies). If you read that I wrote "Southern Oceans" that encompasses both east and west and my interpretations should have been obvious to you.
I was involved in censusing the WCP population on New Island (Falklands) in 2004/05 and 2005/06, so I guess I probably know it occurs there...
Sorry, I'm not following what you mean: White-chinned Petrel occurs only in the Southern Oceans (except for the odd bird...).
Caspian Tern isn't 'highly pelagic' - it is mainly an inland waters species, or where on marine coasts, those of bays and inlets like the Baltic, not ocean shores much.The fact that WcP and Capian Tern occur in Southern Africa and both sides of the Atlantic, both highly pelagic. Caspian Tern doesn't have an odd distribution to my mind?
Caspian Tern isn't 'highly pelagic' - it is mainly an inland waters species, or where on marine coasts, those of bays and inlets like the Baltic, not ocean shores much.
The fact that WcP and Capian Tern occur in Southern Africa and both sides of the Atlantic, both highly pelagic. Caspian Tern doesn't have an odd distribution to my mind?
Rafael expresses the same as me, just a bit better, just above here :t:I've seen Caspian Tern in Gambia, Namibia and Florida, all on Atlantic coasts. I had a look at a distribution map and ocean coasts they use habitually, especially outside the breeding season, include both North and South Atlantic, Pacific and Indian. I think you might be a little off-beam here Nutty.
John
Well, there are quite a few around the Falkland Islands (I even remember catching them by hand overnight assisting a ringer on Kidney Island in 1987) which is generally held to be in the South Atlantic on the West side: and they can also be seen off Namibia which is on the other side of the same ocean. There is more to the Atlantic than the bit between Europe and the USA.
John
John,
Would that ringer have been Shane Wolsey?
I helped in ring White Chinned Petrels on Kidney in 1987.
Cheers
Alan
The WCP were big and the bills fearsome up close, but they were so placid when you had hold of them. Not at all like the Sooty Shears that squawked and kicked and bit and tried to flap - or vomited....
Cheers
John
I knew Caspian Terns occurred in Eastern Europe and east to Central Asia, around Sweden in summer and in winter knew they occur in Africa around Southern Asia. Then I discovered there was a population in North America which really baffled me as it's name suggested it was a more Eurasian Bird! Now I have discovered the species is found in most of the world thanks to this thread.
Boutillier et al 2014 (Conserv Genet 15:275–281. doi 10.1007/s10592-013-0536-1) found "Evidence for genetic differentiation among Caspian tern populations in North America", and recommended that three of the breeding regions should be designated as separate management units. "However, due to extremely low levels of cytochrome b variation, we cannot conclude whether these populations also represent evolutionarily significant units."
The largest known colony of 6000bp is on the Columbia River.
There appears to be no similar research published recently on the species away from the US.
MJB