Melbourne's grassland bullant is known from just eight sites
Melbourne’s grassland bullant survives at just eight known sites in the city’s native grasslands.
The species, Myrmecia nobilis, lives in grassland of which less than 0.5% remains. That habitat once stretched from the Yarra River to the South Australian border.
The Victorian National Parks Association’s Melbourne’s Grassland Bullant report is the first dedicated study of Myrmecia nobilis. Community Bank, Altona and Laverton funded the report, and a group of naturalists helped develop it.
Adrian Marshall, Grassy Plains Network Facilitator at the Victorian National Parks Association, said: “I was amazed when I first heard about Myrmecia nobilis, I had never imagined there would be a rare grassland specialist bullant, let alone one found only in Melbourne.”
In the remaining grasslands, the bullants forage through leaf litter and around the base of grass tussocks. They hunt weevils to feed their larvae.
During summer, Myrmecia nobilis can tolerate the baking heat of open grasslands. That heat keeps competitor ant species away.
Because the species does not depend on nectar, it can persist where flowering plants are sparse. That trait gives the ant an edge in open native grassland.
Flora and Fauna Guarantee Act
However, the same traits also leave Myrmecia nobilis vulnerable in fragmented habitat across Melbourne. The species relies on grassy country that has largely been decimated.
Queens are flightless, so broken-up habitat makes new colonies hard to start. Colonies are also small, with about 20 ants.
Fire poses a direct risk, especially in autumn when queens disperse to build new colonies. As a result, the report calls for careful use of fire at occupied sites.
A submission has gone to Victoria’s Scientific Advisory Committee to list Myrmecia nobilis as threatened under the Flora and Fauna Guarantee Act. That law is Victoria’s main nature protection law.
If Victoria grants the listing, the move would increase legal protection, raise awareness and help attract research funding for Myrmecia nobilis.
Marshall said, “Understanding these ants better is essential if we’re going to save both them and the grasslands they call home.”
The report also sets out site management steps for the grasslands where the ants live. Those steps include limits on tree encroachment near nesting sites, avoiding soil compaction and maintaining open grassland structure.
Meanwhile, the report identifies restoration of threatened grasslands in Melbourne as a priority for the species. It also notes that Myrmecia nobilis survives only in native grassland.
Less than 0.5% of that original grassland remains between the Yarra River and the South Australian border. Following that loss, isolated colonies face higher risks from fragmentation, fire and small colony size.
