Nature News November – Eltham Copper Butterflies, a summer highlight
Posted on 3 November, 2016 by Connecting Country
For this month’s Nature News, found on page 31 in this week’s Midland Express (2nd November 2016), local ecologist Elaine Bayes shares her interest and knowledge of the incredible life cycle and local community efforts to protect one of our special endangered species, the Eltham Copper Butterfly.
As the weather starts to warm up, from November to March each year, Eltham Copper Butterflies will emerge from underground caterpillars. This small and endangered butterfly is endemic to Victoria where it was once widely distributed. Eltham Copper numbers have declined due to land clearing and inappropriate fire regimes, to a point where they were believed to be extinct in the 1950’s. They were rediscovered in Eltham in 1986. These butterflies are currently listed as endangered in Victoria and nationally.
The reason I am fascinated with Eltham Coppers is they have a weird and wonderful and totally dependent three-way relationship with Notoncus ant species and Sweet Bursaria plants. Notoncus ants are nocturnal ants which live underground including at the base of Sweet Bursaria plants. Eltham Coppers lay their eggs at the base of a Sweet Bursaria plant and once hatched the larvae is guided into the ant nest and protected. The larvae over-winters in the nest and ants lead them out to graze at night exclusively on the leaves of Sweet Bursaria. In return, the ants feed on sugars which are excreted by the larvae’s honeydew gland.
How does that happen? How can they train ants to carry them to bed and take them out to dinner and keep them safe? Its quite complex and includes production of a range of chemicals and pheromones which makes the ant think they are one of their brood and need looking after and protection. It doesn’t end there, as pupae and larvae also make a range of noises which trick the ants into not recognising them as a threat and even protecting them.
The four known Eltham Copper populations across Victoria are now totally separate. This means that butterflies are no longer able to move between populations to exchange genetic material and make them more resilient to disease. The Castlemaine population is centred in four main areas in our local parks. Ensuring that these areas are protected from prescribed burning, inappropriate development or invasion by weeds is critical for their long term survival. As is finding and protecting new populations. The Castlemaine Field Naturalists Club and Friends of Kalimna Park have protected local populations for decades by removing woody weeds, monitoring populations and negotiating with the state government on fire regimes.
Thanks to this community effort we have the largest stronghold of Castlemaine Copper Butterflies in Victoria – well that’s what I think they should be called!