www.ukbutterflies.co.uk

First of all, we thought it was nice to see Caroline Bulman from Butterfly Conservation on John's Home patch.

"The UK has 59 species of butterflies, 57 that are native and two that migrate here, the Painted Lady and the Clouded Yellow"

Some might have argued for more butterfly species, but from that statement one might have assumed that a native United kingdom butterfly, was one that was able to complete it's life cycle here, with a sustainable population.
What are your thoughts?

Here was the link:

https://www.bbc.co.uk/iplayer/episode/m ... home-patch

Always an interesting topic. There is a sort of descending order of degrees of residency/migration:

Red Admirals complete their life cycle in the UK, and though numbers are largely topped up by migrants every year, it now seems to be clear that the species can survive the winter in the UK in all stages of their life-cycle. Vince Massimo's ongoing study of this subject on UKB is a fascinating and informative read.

Painted Ladies complete their life cycle in the UK, but only in exceptional circumstances do they get through the winter in one or other of their stages of that life cycle. I think I read somewhere that they cannot survive temperatures below 4 degrees in any stage. However, they are a regular migrant to the UK, sometimes in considerable numbers, and sometimes at surprising times of the year (January, for example). There is a return migration in the autumn.

Clouded Yellows also complete their life cycle in the UK, but rarely make it through the winter in any of their life cycle stages. There is firm evidence that on occasion, however, they do survive the winter in sheltered southern coastal locations, such as the undercliffs in the Bournemouth area, probably as a caterpillar. Again, they are a regular migrant to the UK, appearing every year and sometimes in good numbers. I believe a return migration in the autumn has also been mooted.

In recent years, Long-tailed Blues have also successfully completed their life cycle in the UK in southern coastal counties, but winters here and in Northern Europe generally are too cold for them to survive at any stage of this cycle, and any UK-born adults migrate south again if they can before cold sets in in autumn. Migrations to the UK seem to be on the increase - adults are recorded most years, but larger numbers were seen in 2013, 2015 and 2019.

Recent developments may have to redefine the situation around the Large Tortoiseshell.

Other species are either full UK residents, routinely completing their life cycles here and surviving the winter in one stage or another, or occasional migrants/vagrants which either cannot do so (Monarch for example) or which theoretically could but do not generally arrive in numbers sufficient to achieve a sustainable population (continental Swallowtail for example).

Happy to be set right on this if I've not reflected reality correctly, or maybe done so too simplistically!

Dave

millerd wrote: ↑Thu Jun 18, 2020 8:52 am Always an interesting topic. There is a sort of descending order of degrees of residency/migration:

In literature there might have been a slightly different definition between "resident" and "native" with reference to butterfly species, with native having had more of a historical context.
One thought was, a "vagrant" butterfly species might have implied migration both ways (immigration and emigration), terms usually used for the movement of people, but might have helped others in understanding a specific butterfly species.
A more helpful understanding of “vagrant” might have referred to an immigrant butterfly that arrived on a “favourable” weather system, that had little or no native flora it needed, to help the species complete sustainable life cycles.
Late Spring, early Summer Migration timing with favourable weather systems.
Movement of species from more southerly, foreign localities to more northerly United Kingdom locations, might have usually occurred, when temperatures in the more southerly foreign regions were warmer first and butterfly life cycles were more advanced.

Kind Regards

PhilBJohnson wrote: ↑Thu Jun 18, 2020 3:51 pm
Late Spring, early Summer Migration timing with favourable weather systems.
Movement of species from more southerly, foreign localities to more northerly United Kingdom locations, might have usually occurred, when temperatures in the more southerly foreign regions were warmer first and butterfly life cycles were more advanced.

The influence of weather systems on both regular (e.g. Painted Lady) and less usual (Camberwell Beauty for example) species is undeniable. Influxes of the Camberwell Beauty tend to originate in Scandinavia and Eastern Europe, and a run of easterly winds from these areas at the time of their emergence can well bring some this way. The extraordinary immigration of Scarce Tortoiseshells a few years back almost certainly derived from such conditions, with the source of the airflow at that time being a long way east. Another example is the Monarch. Monarchs appearing in the UK tend to arrive in early autumn, and largely towards the southwest of the country. This coincides with the North Atlantic hurricane season, and with the butterfly's southward migration along the US eastern seaboard towards Florida. The likely scenario is that a typical hurricane arrives from the southeast, recurves north then northwest, grazing the US coast when the Monarchs are streaming south, picks up a few and accelerates across the North Atlantic towards the British Isles becoming an extratropical depression as it does so. Systems of this sort can cross the Atlantic in only a couple of days, and Monarchs are particularly robust creatures.

Dave

Dave, I would take issue with your remark that Clouded Yellows rarely make it throgh the winter in any of their stages. Since I had the opportunity to monitor the deveelopment of larvae through the winter of 1998 - 1999, and the subsequent emergence of adults beginning 26 March 1999, overwintering has occurred in almost every year in varying numbers. Although there is still no cast-iron proof of successful overwintering elsewhere than the Bournemouth cliffs, there is good circumstantial evidence for overwintering at the Branscombe area in East Devon, at Portland and in the Swanage area, including Ballard down.

M.

Hi Mikhail,

Very happy to be corrected on that one - I knew they had been making it through the winter from time to time, but had no idea that this was becoming more frequent and indeed possibly more widespread. This is very welcome, of course.

Thanks for that,

Cheers,

Dave