Martins mass flock to shelter in Leigh Street, Adelaide city, trees an 'amazing' spectacle but concern over droppings
Tree martins by the thousands started to descend en masse at dusk to shelter in the callery pear trees lining Leigh Street in Adelaide from around 2014 in the warmer months of January to May, creating a tourist atttraction but also concerns about the birds' droppings from the street's restaurants.
Images courtesy Green Adelaide and Leigh Street
Trees in Leigh Street, Adelaide city, became home over a decade for Australia’s biggest roost of martins leading to the thousands of birds’ becoming a tourism wonder and their droppings prompting complaints by the street’s businesses to the Adelaide city council again in 2024.
The tree martins were estimated to number 10,000. The South Australian government urban environment agency Green Adelaide said tree martins, a type of swallow, were a declining species in the Mount Lofty and Adelaide area so, from a conservation view, having them in the heart of the city was “quite amazing”.
Green Adelaide ecologist Jason Van Weenen told ABC (Australian Broadcasting Corporation) News, Adelaide, that tree martins favoured the Callery pear trees lining Leigh Street to stay safe from predators, especially the peregrine and Australian hobby falcons. Just before dark every evening between January and May, thousands of the tiny birds swirled in a flock gathering overhead before plummeting down in a coordinated rush. The birds initially stayed high to avoid the city's falcons before darting through the danger zone, using safety in numbers.
Tree martins’ natural nest sites were hollows in horizontal branches of gum trees and steep creek banks, but across Adelaide many had resorted to the hollow steel cross-arms of Stobie poles and vent holes in older buildings. The exotic Callery pear trees (Pyrus calleryana), originally from China and Vietnam and planted as street trees across much of Adelaide, attracted the martins as a great place to sleep. They sleeping birds looked very similar to the leaves on the tree, possibly providing a camouflage. The noise, light and people of Leigh Street and its restaurants at night also could help deter predators.
But, in 2024, Adelaide city council staff were cleaning Leigh Street three times a day to keep up with the volume of bird droppings from the tree martins flocking there. Marshall King, an owner of Pink Moon Saloon in Leigh Street told InDaily Adelaide that, if the droppings “weren’t so disgusting”, the martins “would be a beautiful spectacle. I’ve seen tourists walking past… they think it’s just amazing, they’re filming and everything, it looks like a real sort of David Attenborough migration-style spectacle".
In response to business owners’ complaints, the city council investigated bird control technology including sonar but found it risked eyesight in a pedestrian street. Netting the trees also was ruled out because of their size. Extra pruning minimised tree overhang into dining areas while the council had removed one smaller tree next to Shobosho outdoor dining area that was to get a canopy.
Meanwhile, Green Adelaide had resources on their website, and even a sign in Leigh Street, encouraging people to see the birds as an attraction. As Adelaide's temperatures dropped around May each year, most the birds departed for warmer places, some venturing as far as New Guinea and Indonesia.
