April 14th, 2011

There have been insects active for 5 weeks now, but the midge and other flies are often overlooked. And although moths and fireflies were found around the sap pails since the start of April, it is the butterflies that draw our attention. I assume that some butterflies were active on Saturday when the temperature rose above 20C, but I saw my first ones today.

I went to the south-facing slopes to find two species of butterfly – the Eastern Comma and the Mourning Cloak. These two species overwinter as adults, spending several months tucked away in hollow logs, underneath loose bark, or finding spaces between tree roots. As spring arrives and the snow melts they emerge from winter hibernation and begin to feed. These are not nectar-feeders because few flowers are blooming at this time. Instead, they feed on sap to get their energy and mud or animal droppings to gain valuable minerals.

They have to maintain an elevated body temperature to be able to fly, and employ several methods for this on the cooler days. The first is to simply find an area of the forest where warm sunlight is available and the wind is blocked – a south-facing slope is perfect. There, you might see a couple of behaviours exhibited. Many use dorsal-basking, where the butterfly will land, turn its body perpendicular to the sun and angle its wings to reflect the sunlight onto its body where the flight muscles are located. Others acquire heat by pressing their bodies against the dead leaves on the forest floor that have been absorbing the heat of the sun.

They are very well camouflaged against the dead leaves on the ground, so the best way to find them is to take a careful stroll through the leaves where the slope faces south, on one of the many beautiful days that are ahead…

Mourning Cloak Dorsal Basking

Eastern Comma absorbing heat from the leaves