Dining at a café or in the garden? It can be a difficult choice, even for noisy miners.
But rather than join the latte-drinking café set, it seems these vocal visitors will more actively defend what’s on the menu in our nectar-rich backyards. And it’s a predilection that could be costing other native birds dearly.
A honeyeater found throughout south-east Australia, the noisy miner lives in social groups and is one of the most aggressive birds in the landscape – its mobbing behaviour can drive out other species and ultimately threaten local biodiversity. Now it’s believed that gardeners could be complicit in the miner’s monopolisation of habitat, by inadvertently creating the perfect dining options.
UNE researcher Jade Fountain used taxidermied models of food competitor, non-food competitor and predator birds in rural, garden and café settings to test the influence that other birds and food availability had on miner behaviour.
“I thought we would see a lot more investment in mobbing competitor birds around cafes, where miners can simply pinch food off people’s plates and they have more time for vigilance,” Jade says. “But what we actually found was greater mobbing responses in suburban gardens, where their aggression was more intense and lasted longer.”
While there is more to learn about miner behaviour in different habitats in different seasons, the findings suggest that we humans might be catering to miners in unexpected ways.
“Our research indicates that by extensively planting nectar-rich ornamental plants (like grevilleas and callistemons) not normally found in the environment, gardeners could be attracting more miners and creating more competition with other bird species,” Jade says.
Image: Predatory decoys are used to help researchers uncover the behaviour of the noisy miner.
“It may be that we need to consider planting a greater variety of plants that noisy miners might not feed on, and which smaller birds can hide in, instead of the natives that are so often prized for their year-round flowering. Miners obviously think it’s worth their time protecting this high-sugar diet.”
So the miner may be a rather noisy canary in the mineshaft?
“Understanding the dynamics within an environment is important if we want to maintain biodiversity,” Jade says. “We have a responsibility to learn a lot more about how our behaviour is impacting these birds and supporting them to mob other species. It’s completely unintentional, but we may be attracting miners to locations they didn’t previously occupy, and favouring them through our planting choices.”
Not so surprisingly, Jade found that the predator model (a goshawk) attracted large numbers of miners for a longer period as they sought to warn the colony of its presence, while the spotted pardalote “competitor”, smaller in body size and no physical threat to the noisy miner, also came in for some unwanted attention.
“The aggressive responses varied between species and habitats,” Jade says. “How they might vary throughout the year, with changing nectar availability and breeding activity, is worth further investigation.”
