Report from a park user yesterday:
I saw two butterflies in Sleepers Field this morning – a brimstone and a peacock.
Both of these species hibernate in their adult form and emerge in the first sunny days of the year when the temperature reaches 13°C. In yesterday’s sunshine, walkers in the park unbuttoned their coats, and the first butterflies appeared.
Brimstones usually hibernate among tangles of bramble or ivy in sheltered, sunny places, while peacocks hibernate in dark crevices and holes in trees. Peacocks can also be found in garden sheds and outhouses, and they are one of the two species known to regularly hibernate inside houses.
Brimstone butterfly by Charles J Sharp (CC BY-SA 4.0) wikimedia.org
The underside of the wing of each of these butterflies gives them camouflage in their chosen hibernacula. A peacock’s underwing disguises it perfectly in a crevice in the bark of a tree, or the top corner of a spare bedroom wardrobe. The veins on the underwing of a brimstone, hibernating among evergreen plants, look like the veins of a leaf.
Underwing of 1. peacock; 2. brimstone
The populations of both species is increasing:
Brimstone (Gonepteryx rhamni) – Distribution Trend Since 1970’s: +20%.
Peacock (Aglais io) – Distribution Trend Since 1970’s: +16%
Header picture: taken in the park by DKG