Hi I've had a chat with one of our Butterfly transect leaders Please see his comments below:
1) United Kingdom Butterfly Monitoring Survey (UKBMS) started for all butterfly species at Strumpshaw Fen in 2008.
2) We started the swallowtail survey in 2010.
3) 2009 A good total for all species - the year of the painted lady invasion; about 1000 crossed the sandy wall in an hour!
4) 2012 was a very wet year.
5) This year promised to be a bumper year until August's weather change; it also effected the swallowtail second brood numbers.
6) Unfortunately, our Transect does not include the favored habitat of the white admiral so we only record a very few on our survey. There is nothing to suggest a fall in these numbers though.
7) Many insects go unrecorded as they are outside the parameters of our Transect route. This together with the fact that recording takes place over an hour and a half per week, it's not surprising that rarities like the silver washed fritillary that visit the fen go unrecorded. It's very much chance and circumstance but if the data is to have credibility we can only record what is there at the time of the survey.
8) We do have another Transect in operation at Sutton Fen and their swallowtail numbers dwarf ours.
9) Milk parsley will only grow effectively if the water table and surrounding vegetation is favorable. The swallowtail was fairly common in Cambridgeshire until their fens were drained. Hence the efforts of the RSPB to maintain the correct conditions for this truly astonishing butterfly.
Year. All species total. Swallowtail total
2008. 616. 6. no dedicated swallowtail Transect in operation
2009. 1458. 4. no dedicated swallowtail Transect in operation
2010. 446. 20
2011. 458. 30
2012. 374. 10
2013. 1160. 16
2014. 1105*. 15
* incomplete as three more weeks to go
In reply to Rachel F:
Keep up the good work Rachel. I note with interest that the woodland trail trimming has apparently taken out some of the bramble that the "Black Admiral" ;-) used to feed on. Hope this does not affect their numbers; being very few anyway.
Not as bad as "Norfolk Walkers Trust" who have destroyed a huge swathe of reed-bed and milk parsley area to create a raised bank path, just so they can attract more walkers and more money. Unfortunately for the wildlife, this was *The Best* breeding site for Swallowtails in Norfolk and many hundreds of Chrysalis must have been bulldozed away!
We spend 90% of net income on conservation, public education and advocacy
The RSPB is a member of BirdLife International. Find out more about the partnership
© The Royal Society for the Protection of Birds (RSPB) is a registered charity: England and Wales no. 207076, Scotland no. SC037654