Monday, 12 May 2014

Coronet flight period

Steve and Xander queried whether their Coronet was early, and in the comments Marc raised the issue of changes in flight times for moths and butterflies in recent years. Below is the data for Coronet in Berkshire, which seems to show a clear difference in the start of the flight period before year 2000 (when it didn't appear until June, which is what the books say) and since 2000 (when an April start is becoming a regular feature).

One potential bias here is that on the Berks database we have far fewer records for pre-2000 than we do since 2000, so to some extent the graphs may just be showing that more recorders are recording more often and therefore stand a better chance of picking up the occasional early emergers, but personally I feel that there has been a definite shift for this and many other species.


  1. Not that it proves anything, but looking back at our records from last year, I note that we first recorded Coronet on exactly the same (early) date as this year, 9th May.

  2. It appears to me that Coronet is one big recent success story. Just looking at my own records, I didn't see one in Bucks until 2008 when a singleton appeared in the garden. Since then I've recorded the following in the county:

    2009 4 records (4 individuals) at 3 sites: 26th June to 5th July
    2010 6 records (7 individuals) at 4 sites: 27th June to 11th July
    2011 8 records (8 individuals) at 5 sites: 5th May to 18th July
    2012 14 records (16 individuals) at 4 sites: 28th May to 8th August
    2013 50 records (236 individuals) at 15 sites: 20th May to 4th September

    These records agree with Martin's graph in that there's still a single peak in July but it does make you wonder if the increasing spread of dates indicates an attempt to become bivoltine.

    In Bucks the records were always Jun/Jul/Aug until 2004 when the first record for May appeared. Since then records from early-May onwards have not been unusual but there has as yet been no record of the species in April. Berkshire is obviously that much closer to the equator!


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