A bird in the hand  

By Dr Helena Stokes, AWC Wildlife Ecologist and Dr Jon Coleman, Queensland Bird Research and Banding Group

From the rainforest-cloaked peaks of North Queensland to the arid mulga woodland in the south-west of the state, scientists have embarked on long-term monitoring of bird populations by catching birds and fitting them with metal leg bands. The technique yields rich information about the birds that live in these places. Bird banding offers answers to questions such as: how long do individual birds live for? Which species are likely to stay in one place their whole lives, and which ones move around? And, is the composition of bird species shifting over time? These studies make an important contribution to Australian Wildlife Conservancy’s (AWC) efforts to understand the ecosystems we manage and to monitor their health through time.

Jon Coleman/Queensland Bird Research and Banding group

WHY BAND BIRDS?

Bird banding (or bird ringing) has been used for many decades; it was one of the earliest scientific methods used to track migrating birds. With continued advances in technology and so many monitoring methods available nowadays for scientists to use, a question often asked is whether there is still a need for the direct capture, handling and banding of birds. The short answer is yes. While technological advances are rapidly changing the way AWC and other researchers monitor wildlife populations, there are some questions we can’t answer at present without capturing and handling birds. Bird banding enables us to individually identify birds, which helps us to investigate longevity, movement, health and body condition, behaviour and social structure, breeding success and productivity. Bird banding in Australia is overseen by the Australian Bird and Bat Banding Scheme, who license banders, coordinate the distribution of bands and collate data on when and where birds are banded. Bands are usually fitted around the bird’s lower leg (or tarsus), with the size and shape of bands widely varying according to different bird species.

Most bird banders are dedicated volunteers, and this includes Dr Jon Coleman and the Queensland Bird Research and Banding Group who have established projects on two of AWC’s Queensland wildlife sanctuaries – Bowra and Brooklyn. Jon has established multiple permanent catching sites on each sanctuary, which are visited annually or seasonally, where he and his team set up ‘mist nets’ to capture birds in the area. Here we delve into these projects, and explore how these findings help contribute to our knowledge of these species and AWC’s Ecohealth monitoring program.

Mel Christi/AWC

LIFE IN THE SEMI-ARID ZONE

Whilst the population ecology or life history characteristics of many Australian birds of the temperate zone are now well known, such information is sadly lacking for birds inhabiting the arid zone (which covers over half of the continent). Longevity or survivorship, productivity, territory size, local movements, breeding seasonality and moult strategies are known for only a handful of arid-adapted species.

Since 2013, every year a dedicated team of citizen scientists and volunteers has visited Bowra, near Cunnamulla in south-west Queensland on Kunja Country, to investigate the population and life history of birds inhabiting the semi-arid zone. To date, the Queensland Bird Banding and Research Group has banded a total of 10,328 individuals of 98 bird species at Bowra, with 617 birds from 37 different species having been recaptured.

Analysis of results shows that rainfall is a major driver of many of the trends observed. Zebra Finches and Budgerigars are two of the first species to explode in number after rainfall. Both are well-documented boom-and-bust species of the arid and semi-arid zone, and make a large contribution to the high numbers of birds caught in ‘wet’ years (indeed, many of the team reminisce on a particularly busy morning in 2022, when a whole flock of budgies flew into a mist net). High numbers of these granivorous species following high rainfall may not be surprising. However, after 10 years of mist netting surveys, we are starting to see more subtle changes in the trends of other bird species, some of which we know far less about. White-plumed Honeyeaters, for instance, also increase in number in response to rainfall, but more gradually compared to granivorous species; suggesting that partially nectivorous birds such as these likely take longer to rebound from drought conditions, like those experienced at Bowra from 2017 to 2019.

Holly Sitters/AWC

On the other hand, we’re seeing that for some of the insectivorous birds, including the Chestnut-rumped and Inland Thornbills, capture rates appear to remain relatively stable; they appear to be more resilient to the fluctuating rainfall and often harsh conditions of the arid zone, being less reliant on the availability of seed and flowering plants.

We’re also discovering some interesting life history information. Take Hall’s Babbler, for instance. These chattering, sociable birds are a mulga specialist of inland Queensland and northern New South Wales, about which little is known. Last year a recaptured individual was confirmed to be at least eight years old: a longevity record for this species. Bowra is a well-known location for this species.

All this information helps us track fluctuations in these species in response to changes in climatic conditions, and can help us determine the efficacy of our land management. Wildlife at Bowra, like many places, is threatened by introduced predators and grazing pressure. Monitoring the trajectories of avian communities and individual species can help alert us to any sudden, unprecedented declines, which helps us to track how species and populations are responding to threats and threat management.

Holly Sitters/AWC

LIFE IN THE HIGH-ALTITUDE TROPICS

Since 2019, banding has also been conducted in a wildly different environment: the high-altitude tropical rainforest of Brooklyn, north-west of Cairns, on Eastern and Western Yalanji Country in Far North Queensland. Researchers and volunteers brave the unpredictable weather conditions and leeches four times a year to set mist nets in the montane rainforest, an area of incredible biodiversity with several endemic bird species. This area is also a hotspot for the iconic Blue-faced Parrotfinch, which draws in bird watchers from all over Australia and overseas. Since 2019, the team have banded 974 birds of 33 species. We hope to discover more about the survival rates, movement and productivity of birds in this area, about which little is known, with this information being particularly important given the vulnerability of upland rainforests to climate change.

Helena Stokes/AWC

A variety of species have been caught so far, ranging from the Grey-headed Robin, one of our main indicator species, to the iconic Golden Bowerbird and feisty Spotted Catbird. There have been some surprising insights into the longevity of some of the bird species calling the montane rainforests home. Small birds such as the Atherton Scrubwren and Mountain Thornbill have been determined to be at least 14 and 15 years old, respectively, and have each been caught at the same location they were originally caught, indicating high site fidelity. Being long-lived and sedentary, these birds are likely to be vulnerable to any habitat or environmental changes. Higher elevation birds captured at these sites, such as the Fernwren and Golden Bowerbird, are also likely to be highly susceptible to climate change, and likely to become more range restricted, being forced to move to increasingly higher elevations as temperatures rise. Monitoring these species is crucial in helping to determine how they respond to environmental changes, and their resilience.

Banding data also helps to inform modifications to our land management strategies. For example, the Blue-faced Parrotfinch is well known to utilise a unique patch of open grassy habitat on Brooklyn, surrounded by the rainforest (this patch was actually cleared for forestry operations many decades ago, and long-serving AWC ecologist, Peter Stanton, spent time working at the site early in his career). A recent decline in the sightings and capture rates of the parrotfinch prompted an investigation into weed and vegetation management in this
area, helping us to tailor our management strategies to promote the persistence of food resources for the parrotfinches.

Long-term monitoring through projects such as those at Bowra and Brooklyn is essential. Population changes occur due to a combination of environmental and climatic variables, management changes and of course threats. It’s not always straightforward to identify cause and effect for fluctuations in these avian communities, but the more we learn about the ecology of these species and identify these patterns, the better we can determine how to manage our sanctuaries into the future.

“This very informative article covers my two favourite birdwatching places in Queensland: Bowra and Mt Lewis on the eastern boundary of Brooklyn. I haven’t seen the elusive Blue-faced Parrotfinch at Brooklyn but have spent many hours looking (like many birdos). I have seen a Redthroat at Bowra. Research and fact finding are crucial for the wise management of important conservation properties like these.”
Brian Snape, former President of Birds Australia (now BirdLife) and long-time AWC supporter

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