-
Welcome to BirdForum, the internet's largest birding community with thousands of members from all over the world. The forums are dedicated to wild birds, birding, binoculars and equipment and all that goes with it.
Please register for an account to take part in the discussions in the forum, post your pictures in the gallery and more.
Caspian Terns North America (1 Viewer)
- Thread starter Himalaya
- Start date
Andy Adcock
Worst person on Birdforum
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.
RafaelMatias
Unknown member
Sorry, I'm not following what you mean: White-chinned Petrel occurs only in the Southern Oceans (except for the odd bird...).
RafaelMatias
Unknown member
Caspian Terns have a cosmopolitan distribution, with the exception of South America.
Nutcracker
Stop Brexit!
Seems to be pretty widespread around shallow seas and large lakes; avoids exposed coasts and deep water (hence not UK!). North to 66°N in the Baltic Sea.
https://www.birdforum.net/opus/Caspian_Tern
https://www.birdforum.net/opus/Caspian_Tern
RafaelMatias
Unknown member
The results shown in THIS PAPER, focused on the North American populations, suggest to me the global biogeography of the species is likely complex, with genetic differences found between birds breeding on the Pacific coast and east of the Rockies.
Farnboro John
Well-known member
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
RafaelMatias
Unknown member
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 interpretation 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...
Last edited:
Farnboro John
Well-known member
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...
Fair enough! :t:
John
Andy Adcock
Worst person on Birdforum
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?
Nutcracker
Stop Brexit!
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.
Farnboro John
Well-known member
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
RafaelMatias
Unknown member
I understood what you meant (afterwords, as in my posts above, I was slow...), just that WCP is really not a good example, as you're comparing what is a mostly continental species with a highly pelagic species. It's like saying that orcas being present on both east and west Atlantic are a comparable situation to Moose/Elk being present on both North America and Europe.
Better analogous examples are Gull-billed Tern, perhaps Roseate Tern, and then a number of ducks, Gadwall, Shoveler, etc.
Caspian Terns disperse mostly along rivers and coastal areas, although occasionally found in oceanic waters (very rare in the Azores, for example), whereas WCP just use all adequate habitat between both land masses; they're really mostly mirrored examples.
Nutcracker
Stop Brexit!
Rafael expresses the same as me, just a bit better, just above here :t:
Alan henry
Well-known member
John,
Would that ringer have been Shane Wolsey?
I helped in ring White Chinned Petrels on Kidney in 1987.
Cheers
Alan
Farnboro John
Well-known member
Yes it was. Lovely bloke. Used to let me have a bath occasionally - showers only up at Mount Pleasant.
Kidney, yes, that's the one. Scuttling about in dunes in the dark looking for seabirds and hoping not to trip over a sealion.... :eek!:
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
Dave Boyle
Well-known member
All the big shearwaters are evil - Buller's are possibly the worst because their necks are so long they can bite you pretty much however you hold them and Fleshy-foots should be renamed Flesh-eating Shearwaters. Its weird how placid White-chins are, especially as Black Petrels are evil, but its also pretty annoying because getting the bird to bite you is often the easiest way to pull it out the burrow
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.
MJB
Well-known member
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
RafaelMatias
Unknown member
