Do you know your 'kar-week-week-kar' from your 'chur-ock-churock’? Do you know which animal sings ‘zit zit zit whooorl’? Unless you’re a bird-loving Tasmanian, you may not recognise the Black Currawong, the Yellow-Throated Honey-eater and the Tasmanian Thornbill.
When Glen Bain moved to Hobart to start his PhD, he quickly learned the calls of the 12 bird species endemic to (only found in) Tasmania, like the Green Rosella and the Yellow-throated Honeyeater. Many other Tasmanian bird species are migratory – flying across Bass Strait to the mainland over winter.
But why would someone need to know bird calls by heart?
Glen is one of five students investigating how native animals feed, move and avoid predators in the Midlands, a highly fragmented landscape. Little is known about the woodland birds that live in this fragmented region. Less is known about the kind of habitat that these birds need to survive.
So, armed with binoculars, data sheets and a keen sense of hearing, Glen is surveying the Midlands for birds.
Recording the dawn chorus
On a cold Midlands morning, I joined Glen on one of his woodland bird surveys. We gathered at Tom Gibson Reserve, one of his 75 study sites. Glen lead the survey, meticulously recording birds seen and heard along the 800 metre transect. For 40 minutes we followed every flutter in the canopy, every movement in the bracken fern. Glen’s ability to differentiate bird calls was remarkable. By the end of the survey he’d noted 25 species.
Glen will visit each site 6 times, and augment his list with audio recordings. These acoustic recordings picked up species that Glen didn’t see or hear on his morning surveys – masked owls, nightjars, and even the critically endangered swift parrot. He’ll then compare his bird list with those recorded in the 1990s by scientist Michael McDonald. He’ll also compare the sites to each other: how many species are found in the woodland sites compared to the grasslands, pastures, weed-infested shrub lands and sites revegetated by Greening Australia?
Nest eggs and bird-eaters
When Glen’s not recording bird song, he’s trying to understand:
- What is eating the eggs and nestlings of woodland birds in the Midlands? He has had cameras set up on 27 nests, to see which animals are nest-raiders. So far he’s caught cats, snakes and other birds in the act!
- If birds have more concealed nests (hidden by dense foliage, for instance) are they less likely to have their nests raided by predators? How should we restore areas so that birds can hide their nests?
- What kinds of habitats do the birds regard as ‘safe’ and which ones are risky for them? This is measured using survey techniques such as ‘flight initiation distances’, measuring how close the birds will let the researcher approach before flying away, and ‘giving up densities’, which looks at how birds balance the need to find food against risk of being eaten.
Glen’s research is one part of a collaboration between the University of Tasmania, Greening Australia, Bush Heritage, the Tasmanian Land Conservancy, the Tasmanian Government and committed landholders.
Greening Australia is keen to make their future revegetation efforts in the Tasmanian Midlands more ‘animal-centric’. The region is highly fragmented, which poses a problem for smaller birds, like wrens and thornbills – they avoid flying too far into the open for fear of being eaten. Glen is helping to improve restoration projects, so that replanted areas support all types of birds, from robins to raptors.
- Kate Cranney, Science Communicator Intern.