No interactions present.
I lived in Norfolk for a year and never saw one. I really must go back and see one.
There were plenty around on Sunday, well we saw 3-4 but other people also said they had seen several and they were flying all around us for long time 5-10 mins.
However this is the best sighting I have had of them on several visits to suitable places in Norfolk.
You might be interested to see Linnaeus's specimens of this species in the Linnean Society's Online Collections. http://www.linnean-online.org/view/insects/papilio_machaon.html
Interesting, only one of the 3 seems to have a location and none of them have dates.
DaveNotton's ID. Does one need them side by side, say as photos, to ID or is it simply geographical distribution?
And this one?
The Swallowtails that are resident in Britain are considered to be subspecies britannicus. Several further subspecies have been differentiated on the continent, of which subspecies gorganus occurs in Britain as an occasional migrant.
Subspecies britannicus is supposed to be a little smaller and to have more black and less yellow on the wings, but the differences in markings are slight. However, there are clear differences in habitat and foodplant between the British and continental subspecies.
For Swallowtails seen in suitable habitat in East Anglia, as for the observation here, then I think most people would assume that they are seeing subspecies britannicus. Swallowtails seen away from the East Anglian fens are much more likely to be subspecies gorganus, which has been most frequently recorded from grasslands in southern England, and in the past has sometimes bred successfully for a few years at a time.
There is some more information about Swallowtails in the UK here:
As a purely personal opinion I am always a bit sceptical about whether subspecies really do represent separate entities, as opposed to natural variation in a species that is widely spread across various habitats, but that debate rapidly becomes difficult given that 'species' is a concept defined by humans to make sense of the huge variety of life, which is in any case continually evolving!
To quote from just one of the research papers on the subject, "We therefore suggest that the entire P.machaon complex is in a labile state as regards speciation throughout its range and the relationships between the various forms are not easily expressed through the traditional species and subspecies concepts":
Clearly this butterfly poses some fascinating research questions, but I'd also want to make sure to enjoy seeing Swallowtails whenever one is lucky enough to have the chance!
Entomologist and biological recorder
In a "..state of change or development.." seems to be the conclusion.
I guess if it was not so scarce here (UK) and its range overlapped the 'continental' forms (both ways) then interbreeding would wipe out the minor differences. In any case, from what you say, interbreeding may already take place.
Is it also possible that some UK ones are bred in captivity and released? And, if so, is it considered ethical?
My personal answers to your two questions would be 'yes' and 'no'.
And in some circumstances releases could be illegal: Section 14 of the Wildlife and Countryside Act "prohibits the introduction into the wild of any animal of a kind which is not ordinarily resident in, and is not a regular visitor to, Great Britain in a wild state", but I guess that leaves some room for argument over whether the continental Swallowtail is a "regular" visitor or not.
For guidance on this see:
and Butterfly Conservation's more general guidance on introductions/re-introductions of butterflies is here:
Good enough for me..(for now!!)
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