2011 BUTTERFLY REPORT

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BUTTERFLY REPORT 2011

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2011 BUTTERFLY REPORT ROB PARKER 2011 was a very confused season, with extremes of weather causing unseasonal flowering of many plants and inevitable knock-on effects for insect life. New earliest-ever emergence times were registered for eight butterfly species, whilst autumn brought latest-ever sightings for five different species. On the other hand, there were long blank weeks midseason, with practically nothing flying. Not only did Purple Emperor, Silverwashed Fritillary and Marbled White all remain in evidence, but unexpected appearances by three other species made an unusually high count of 38 species, although several of these were possibly released specimens. It was another year of poor outcomes for our commoner butterflies, but good news for several UKBAP species. Good recording effort has resulted in decent coverage for the second year of the current five-year period. Annexes A and B provide analysis of the season’s results and compare them with previous years. Weather A second cold winter started with snow before Christmas 2010, and 35 frosty days reduced the survival rates of butterflies and parasites alike. Spring was not particularly early, but it was warm and dry. Judged by historic averages (see Table 1 below) it was 2 degrees warmer, with only 27∙8% of an average spring’s rainfall. Larvae feeding up did well, and flew early. Drought was a frequently heard word in spring and autumn, and East Anglia was much drier than the rest of UK. Although late June and early July were fine, and suited Silver-washed Fritillary and White-letter Hairstreak, the rest of summer was below par. An extended autumn was warm and sunny, yet many species produced disappointing second broods.

Table 1. 2011 Weather for East Anglia Season Winter 10/11 Spring Summer Autumn

Mean Temp

Anomaly

Sunshine

Anomaly

Rainfall

Anomaly

ºC

ºC

hrs

%

mm

%

3∙5 10∙6 15∙7 12∙9

-0∙8 2∙1 -0∙2 2∙4

121 563 528 402

69 125 90 124

132∙1 27∙8 179 81∙3

90 21 119 47

Source: www.metoffice.gov.uk/climate/uk/2011 Anomalies are measured against the 1971 to 2000 averages [as last year].

Trans. Suffolk Nat. Soc. 48 (2012)


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