Have not been a subscriber for many a year, hence am not up to speed with the current thinking regarding the above, just what is the official position regarding ''acceptance'' or otherwise of ship borne migrants?
Cheers
The guidelines are attached. The species needs to be considered capable of vagrancy on its own account and no evidence of artificial shelter, feeding, etc.
All the best
Paul
No change really to the policy of vagrancy since that document. Little doubt in my mind that a few Yank sparrows may have well hitched a ride at sometime.
As I understand it...a “helping hand” ie ship assistance is a no no!
However birds that have been introduced and form “self sustaining” populations are kosha.
Having trouble reconciling this with the former, as has been demonstrated over past millennia, all manner of organisms (plants with host species) and various mammals, fish and invertebrates have been introduced and have become established. A distinct lack of purity in UK flora and fauna then?
One could introduce a veritable plethora of organisms to these shores and they would profligate!
Point being...what is so pivotal about “self sustaining”, surely a ship assisted mig deserves more merit than species deliberately introduced for ornamental collections, sport, falconry or for whatever other reason?
Just saying......
"Ship assistance is not necessarily a bar to inclusion on the British List, provided the bird was not confined, sheltered or provisioned during its journey."
I and the species is capable of getting here unaided. It is the latter aspect that led to review of the Thrasher, Towhee, Lark Sparrow, etc with the conclusion that they could make it unaided.
The guidelines are attached. The species needs to be considered capable of vagrancy on its own account and no evidence of artificial shelter, feeding, etc.
All the best
Paul
"The Committee recently amended the wording of its policy on ship assistance to reflect better the Committee's views, as follows:
That the species might be expected to arrive in Britain naturally and without ship assistance (ie the species is migratory and its migratory route matches that of other species believed to occur naturally[/B])."
Exactly how does Ancient Murrelet fit into this scenario? Or Long-billed Murrelet? Actually you can use the first as support for the second, but applying that policy to the first is nonsensical, and makes a nonsense of the policy. Neither of these birds have a migratory route by which they might be expected to arrive in Britain naturally. The committee's views are unsustainable.
Well not quite. The occurrence of North Pacific 'seabirds' in Western Europe was established even prior to the 1990 Ancient Murrelet, eg by Aleutian Tern in 1979 and (I think) a Crested or Parakeet Auklet at some other location. And of course it's all been proved to be a well established vagrancy pattern (Tufted Puffin, two Long-billed Murrelets inc Romania, GW/SB Gulls various) so I cannot see how this contradicts the point that 'the species is migratory and its migratory route matches that of other species believed to occur naturally', if you extend migratory to 'dispersive' in the case of Alcids.
cheers, alan
Being aware of the range of Pacific Alcids that have occurred in Europe I thought you might suggest this. Because of the nature of the migrations of each of these seabirds, what you have just said is that provided a species is migratory, it doesn't matter what direction the migration takes. It is the propensity for migration that generates the capacity for vagrancy: migrational directionality (as well as actual distance of start and finish point from the British Isles) is essentially irrelevant. Which still supports the hypothesis that anything that moves can turn up: while the actual variety of what has turned up shows that it is impossible to rule anything out on flight capacity, because the weather variables can compensate for the limitations of the creature.
Naturally this is all applicable to dispersion as well, and the range of species dispersing is wider than that of species migrating.
Which is all good news for the twitcher suffering from diminishing returns: the species options for future vagrancy from the Nearctic at least are considerable.
John
Has this actually been reviewed by BBRC/BOURC? I know it's been discussed on here many many times, but they do anything by way of formal review?
cheers, alan
Yes - announced formal review in 2006 and announced retained in Category A in 2012. 41st Ibis report attached.
All the best
Paul
So what about that Snowy Sheathbill?