Normalized Weekly Abundance

The periods of 1990-2002 and 2003-2015 were analysed and displayed separately to allow any shift in flight time over the last 26 years to be discerned. The tick marks on the week number axis are between the two bars for that week's data. (This is how Google Charts does it). The heights of the bars of the two periods have been normalized to show abundance as if the same number of records had been submitted during each period. This allows crude comparison of the species' abundance in both 13-year periods.

Dingy Skipper


Grizzled Skipper


Essex Skipper


Small Skipper


Large Skipper


Orange Tip


Large White


Small White


Green-veined White


Clouded Yellow




Wall Brown


Speckled Wood


Small Heath




Meadow Brown




Marbled White


Silver-washed Fritillary


Dark Green Fritillary


White Admiral


Purple Emperor


Red Admiral


Painted Lady




Small Tortoiseshell




Duke of Burgundy


Small Copper


Purple Hairstreak


Green Hairstreak


White-letter Hairstreak


Black Hairstreak


Small Blue


Holly Blue


Brown Argus


Common Blue


Chalkhill Blue