The fourth Aussie Backyard Bird Count has just ended, with nearly 2 million birds from 635 species submitted to the BirdLife Australia app. The count, which is in its fourth year, has created a national database of birds found in our backyards.
We don’t know yet exactly how many people participated this year, but more than 60,000 people submitted checklists in 2016. Participants span the whole country, though participation is highest in our urban areas. By surveying our backyards (rather than “good” bird spots), these citizen scientists provide ecologists – like me – with information from urban areas we would not otherwise sample.
This includes data on a range of common bird species that are not frequently analysed because these species are believed to be secure. One of the most surprising results is a decline in the frequency of occurrence of the laughing kookaburra across southeast Australia.
Everyone has a bird story – and fortunately for ecologists, everyone is willing to share them. With 85% of Australia’s population living in cities and towns, birds are an important connection to our natural environment.
But birds are also good environmental indices. They’re generally easy to measure, they respond quickly to environmental change and we know a reasonable amount about the ecology of most species.
Between 1998 and 2014, BirdLife Australia volunteers collected a significant amount of data. This was used to develop a terrestrial bird index in 2015 – a bird “Dow Jones” to track our biodiversity. It was here that the decline in kookaburras was first identified.
The data were drawn from BirdLife Australia’s ongoing atlas project, now called Birdata. However, there are biases in this data set, as people obviously like to go birdwatching where they will see more birds. This may inflate the frequency of encountering some species and decrease the chances of encountering others – particularly rare and cryptic species.
For the last four years, we’ve asked volunteers to add to this data by counting birds around their home for a week in October, when many birds are highly active and visible. These counts complement the data already available in Birdata by allowing access to backyards across Australia, which are generally poorly represented in the larger data set.
While there are still limitations in the Backyard Bird Count data, such as the risk of mis-identification, for common species like the laughing kookaburra we can generally be confident that the identification is correct. Even if the same bird is counted multiple times, our models report only a species’ presence or absence, so inflated numbers don’t affect the trend.
Are kookaburras really declining?
The below figures show modelled trends for the kookaburra across metropolitan Melbourne and Sydney. These figures are derived from the volunteer-collected Birdata, much of which comes from green spaces and remnant vegetation in these landscapes.
I wondered whether these declines are true changes in the populations, or reflect a change in the way kookaburras are using the landscape, possibly moving into the matrix of urban backyards that just don’t get surveyed. Looking solely at the backyard count data, I found similar trends in the reporting rates of kookaburras as those in the models, supporting that this decline is at the population level. What started out in 2014 as a way of engaging the broader community with their birds is now collecting useful ecological data.
Further exploration of the ABBC data across other capital cities found some interesting things. In both Perth and Hobart, where the kookaburra is considered an introduced species, the birds are recorded more frequently than in Melbourne and across the ACT. In Perth, increases in 2016 compared to previous years suggest an increase in the species there.
While three years does not make a trend, Aussie Backyard Bird Count data from heavily urbanised areas suggest we are seeing a decline in this iconic species in the eastern capitals. Likely reasons for this are the loss of nesting hollows and possibly reductions in the availability of prey as we increasingly modify our urban landscapes. We don’t really know as this is not an area that has been researched.
We need citizen scientists
Collecting enough data (especially from the backyards of towns and cities) to detect these kinds of changes can be an overwhelming task. This is where citizen science programs like the Aussie Backyard Bird Count can help.
As well as helping ecologists track large-scale biodiversity trends, it also gives people the chance to connect with their natural environment and gain a greater appreciation of our unique fauna.
As with all citizen science projects, there are limitations in the data being collected. However, the Backyard Bird app has been designed to make counting as simple and standardised as possible, providing confidence in the tally of common and “iconic” species, and filling in the gaps found in other data sets.
The good old kookaburra is neither rare or cryptic. If anything, if people are seeking out “good” bird habitat to survey we would expect that kookaburras would be one of those species subject to inflated reporting. But this is not what we encountered.
If we are starting to see declines in species that we have traditionally considered secure, what does this mean for those that are already at risk? Once all the data from the Aussie Backyard Bird Count have been collated and vetted we will continue to explore the developing trends in Australia’s urban birds. Increasing engagement and awareness in our communities can help ensure our backyard birds are still around to count next year.
John Woinarski, Charles Darwin University; Brett Murphy, Charles Darwin University; Leigh-Ann Woolley, Charles Darwin University; Sarah Legge, Australian National University; Stephen Garnett, Charles Darwin University, and Tim Doherty, Deakin University
Cats kill more than a million birds every day across Australia, according to our new estimate – the first robust attempt to quantify the problem on a nationwide scale.
By combining data on the cat population, hunting rates and spatial distribution, we calculate that they kill 377 million birds a year. Rates are highest in Australia’s dry interior, suggesting that feral cats pose a serious and largely unseen threat to native bird species.
This has been a contentious issue for more than 100 years, since the spread of feral cats encompassed the entire Australian mainland. In 1906 the ornithologist A.J. Campbell noted that the arrival of feral cats in a location often immediately preceded the decline of many native bird species, and he campaigned vigorously for action:
Undoubtedly, if many of our highly interesting and beautiful birds, especially ground-loving species, are to be preserved from total extinction, we must as a bird-lovers’ union, at no distant date face squarely a wildcat destruction scheme.
His call produced little response, and there has been no successful and enduring reduction in cat numbers since. Nor, until now, has there been a concerted effort to find out exactly how many birds are being killed by cats.
Counting the cost
To provide a first national assessment of the toll taken by cats on Australian birds, we have compiled almost 100 studies detailing the diets of Australia’s feral cats. The results show that the average feral cat eats about two birds every five days.
We then combined these statistics with information about the population density of feral cats, to create a map of the estimated rates of birds killed by cats throughout Australia.
We conclude that, on average, feral cats in Australia’s largely natural landscapes kill 272 million birds per year. Bird-kill rates are highest in arid Australia (up to 330 birds per square km per year) and on islands, where rates can vary greatly depending on size.
We also estimate (albeit with fewer data) that feral cats in human-modified landscapes, such as the areas surrounding cities, kill a further 44 million birds each year. Pet cats, meanwhile, kill about 61 million birds per year.
Overall, this amounts to more than 377 million birds killed by cats per year in Australia – more than a million every day.
Which species are suffering?
In a related study, we also compiled records of the bird species being killed by cats in Australia. We found records of cats killing more than 330 native bird species – about half of all Australia’s resident bird species. In natural and remote landscapes, 99% of the cat-killed birds are native species. Our results also show that cats are known to kill 71 of Australia’s 117 threatened bird species.
Birds that feed or nest on the ground, live on islands, and are medium-sized (60-300g) are most likely to be killed by cats.
It is difficult to put a million-plus daily bird deaths in context without a reliable estimate of the total number of birds in Australia. But our coarse assessment from many published estimates of local bird density suggests that there are about 11 billion land birds in Australia,
suggesting that cats kill about 3-4% of Australia’s birds each year.
However, particular species are hit much harder than others, and the population viability of some species (such as quail-thrushes, button-quails and ground-feeding pigeons and doves) is likely to be especially threatened.
Our tally of bird deaths is comparable to similar estimates for other countries. Our figure is lower than a recent estimate for the United States, and slightly higher than in Canada. Overall, bird killings by cats seem to greatly outnumber those caused by humans.
In Australia, cats are likely to significantly increase the extinction risk faced by some bird species. In many locations, birds face a range of interacting threats, with cat abundance and hunting success shown to increase in fragmented bushland, in areas with high stocking rates, and in places with poorly managed fire regimes, so cat impacts compound these other threats.
Belling the cat
The threatened species strategy also prioritised efforts to control feral cats more intensively, eradicate them from islands with important biodiversity values, and to expand a national network of fenced areas that excludes feral cats and foxes.
But while fences can create important havens for many threatened mammals, they are much less effective for protecting birds. To save birds, cats will need to be controlled on a much broader scale.
We should also remember that this is not just a remote bush problem. Roughly half of Australia’s cats are pets, and they also take a considerable toll on wildlife.
While recognising the many benefits of pet ownership, we should also work to reduce the detrimental impacts. Fortunately, there is increasing public awareness of the benefits of not letting pet cats roam freely. With such measures, cat owners can help to look after the birds in their own backyards, and hence contribute to conserving Australia’s unique wildlife.
We acknowledge the contribution of Russell Palmer (WA Department of Biodiversity Conservation and Attractions), Chris Dickman (University of Sydney), David Paton (University of Adelaide), Alex Nankivell (Nature Foundation SA Inc.), Mike Lawes (University of KwaZulu-Natal), and Glenn Edwards (Department of Environment and Natural Resources) to this article.
John Woinarski, Professor (conservation biology), Charles Darwin University; Brett Murphy, Senior Research Fellow, Charles Darwin University; Leigh-Ann Woolley, Research Associate, Charles Darwin University; Sarah Legge, Associate Professor, Australian National University; Stephen Garnett, Professor of Conservation and Sustainable Livelihoods, Charles Darwin University, and Tim Doherty, Research Fellow, Deakin University
The drone market is booming and it is changing the way we use airspace, with some unforeseen consequences.
The uptake of remotely piloted aircraft (RPAs) has been swift. But despite their obvious benefits, concerns are growing about impacts on wildlife.
In our research we investigate whether regulation is keeping pace with the speed of technological change. We argue that it doesn’t, and we suggest that threatened species might need extra protection to ensure they aren’t harmed by drones.
But researchers are also discovering that RPAs have negative impacts on wildlife, ranging from temporary disturbances to fatal collisions.
Disturbance from vehicles and other human activity are known to affect wildlife, but with the speed that drones have entered widespread use, their effects are only just starting to be studied.
So far, the regulatory response has focused squarely on risks to human health, safety and privacy, with wildlife impacts only rarely taken into account, and even then usually in a limited way.
It is not uncommon for regulatory gaps to arise when new technology is introduced. The rapid growth of drone technology raises a series of questions for environmental law and management.
We have reviewed evidence for wildlife disturbance and current drone policies and found that the law is playing catch-up with emerging technology.
This is particularly important in New Zealand, where many threatened species live outside protected reserves. Coastal areas are of particular concern. They provide habitat for numerous threatened and migrating species but also experience high rates of urban development and recreational activity. Different species also respond very differently to the invasion of their airspace.
Where “flying for fun” and pizza delivery by drone combine with insufficient control, there is potential for unanticipated consequences to wildlife.
RPA and red tape
When competing interests collide, regulation requires particular care. Any rules on RPAs need to cater for a wide range of users, with varying skills and purposes, and enable beneficial applications while protecting wildlife.
There are strong social and economic drivers for the removal of red tape. Australia and the United States have introduced permissive regimes for lower-risk use, including recreational activity. In New Zealand, RPAs are considered as aircraft and controlled by civil aviation legislation.
Wildlife disturbance, or other impacts on the environment, are not specifically mentioned in these rules and control options depend on existing wildlife law.
The lack of consideration of wildlife impacts in civil aviation rules creates a gap, which is accompanied by an absence of policy guidance. As a consequence, the default position for limiting RPA operations comes from the general requirement for property owner consent.
RPA and spatial controls
RPA operators wanting to fly over conservation land have to get a permit from the Department of Conservation, which has recognised wildlife disturbance as a potential issue.
On other public land, we found that local authorities take a patchy and inconsistent approach to RPA activity, with limited consideration of effects on wildlife. On private land, efforts to control impacts to wildlife depend on the knowledge of property owners.
Protection of wildlife from RPA impacts is further confounded by limitations of legislation that governs the protection of wildlife and resource use and development. The Wildlife Act 1953 needs updating to provide more effective control of disturbance effects to species.
Marine mammals get some protection from aircraft disturbance under species-specific legislation. Other than that, aircraft are exempt from regulation under the Resource Management Act, which only requires noise control for airports. As a result, tools normally used to control spatial impacts, such as protective zoning, setbacks and buffers for habitat and species are not available.
This makes sense for aircraft flying at 8,000m or more, but drones use space differently, are controlled locally, and generate local effects. It is also clear that equipment choices and methods of RPA operation can reduce risks to wildlife.
Keeping drones out of sensitive spaces
Dunedin City Council in New Zealand recently approved a bylaw banning drones from ecologically sensitive areas. This is a good start but we think a more consistent and universal approach is required to protect threatened species.
As a starter, all RPA operations should be guided by specific policy and made available on civil aviation websites, addressing impacts to wildlife and RPA methods of operation. In addition, we advocate for research into regulatory measures requiring, where appropriate, distance setbacks of RPA operations from threatened and at risk species.
Distance setbacks are already used in the protection of marine mammals from people, aircraft and other sources of disturbance. Setbacks benefit species by acting as a mobile shield in contrast to a fixed area protection.
Congestion of space is a condition of modern life, and the forecast exponential growth of RPA in the environment indicates that space will become even more contested in future, both in the air and on the ground. We argue that stronger measures that recognise the potential impacts on wildlife, how this may differ from species to species, and how this may be concentrated in certain locations, are required to deliver better protection for threatened species.
Pip Wallace, Senior lecturer in Environmental Planning, University of Waikato; Iain White, Professor of Environmental Planning, University of Waikato, and Ross Martin, Doctoral Candidate (Coastal Ecology), University of Waikato
The rainforests of Papua New Guinea are home to one of the richest bird populations in the world. But many are threatened by logging and palm oil farming.
Now, a team of researchers led by Edith Cowan University have surveyed the PNG island of New Britain to see how the bird population is faring.
The good news: several bird species, like the Blue-eyed Cockatoo, were found to be doing better than before.
The bad news: the researchers saw only a few New Britain Kingfishers, and some vulnerable species, like the New Britain Bronzewing, Golden Masked-owl and Bismarck Thicketbird, were not seen at all.
Their results, recently published in the journal Bird Conservation International, help to inform the International Union for Conservation of Nature and Natural Resources (IUCN) Red List of Threatened Species.
Male superb fairy-wrens change colour every year, from dull brown to bright blue. But being blue may be risky if you are a tiny bird that is easily spotted by predators.
Published today, our new study found that male fairy-wrens adjust their risk-taking behaviour after undergoing colour change, becoming more cautious while brightly coloured.
Colour and risk
For many males, having beautiful colours is important for attracting choosy females. Researchers think attractive colours come with a cost, so that only the highest quality males can afford to display them. This may be helpful to females looking to select the best mate.
One possible cost of bright colours is increased predation risk, as bright animals are easily seen in their natural habitat. This cost can be dramatic (i.e. being eaten) but may more often involve changes in behaviour to mitigate risk, such as spending more time scanning for predators and being more responsive to perceived threats. Such behaviours are costly because they reduce the time available for foraging and are energetically expensive.
A relationship between bright colours, predation risk and cautious behaviour may seem intuitive; however this is difficult to test. This is because different coloured animals may also differ in their age, size, escape tactics and personality, which can influence both their behaviour and actual predation risk.
To address this, we tested whether individuals adjust their response to risk according to changes in their plumage colour.
Superb fairy-wrens are small, charismatic songbirds. They live in groups with a dominant male and female and, often, several younger males.
These birds are vulnerable to predators such as kookaburras, butcherbirds, currawongs and goshawks. When a group member spots a predator, it gives an alarm call to warn the others. In response, other group members may race for cover, or ignore the alarm and continue about their business.
Male fairy-wrens change colour by replacing dull brown feathers with bright blue, black and indigo ones prior to breeding, turning brown again after the breeding season is complete. Individuals change colour at different times of the year, ranging from the Australian autumn (March-April) to late spring (October).
Although female fairy-wrens have a stable, social partner, when egg-laying time comes, they briefly leave their territory under the cover of darkness and “visit” the male who became blue earliest in the year. Many of the females in the surrounding area prefer the same male, who may father around 70% of the offspring in the neighbourhood. These attractive males are blue for longest (remaining blue for 10-12 months of the year) and so may face the greatest risk of predation.
We gave fairy-wrens different coloured leg bands, allowing us to follow the same individuals over time.
We compared the behaviour of the same males while they were brown and blue, as well as males that remained brown or blue throughout the study. This meant we could test for the effect of colour on responses to perceived risk while accounting for individual differences and possible seasonal changes in behaviour.
We estimated cautiousness in the birds by testing their response to alarm calls. This involved sneaking up on unsuspecting fairy-wrens in their natural habitat and broadcasting fairy-wren alarm calls from portable speakers.
We used two types of alarms: a low-danger alarm, which warns of a moderate threat, such as a predator that is far away, and a high-danger alarm, which signals an immediate threat.
Costs of being blue
Responses to the low-danger alarm included fleeing for cover, an intermediate response (such as ducking or looking skywards) and no response, when the alarm was ignored. Fairy-wrens fled immediately after hearing the high-danger alarm, but differed in the time taken to return to the open.
We found that fairy-wrens were more cautious while blue; they fled more often after hearing low-danger alarms and took longer to emerge from hiding after fleeing in response to high-danger alarms. Blue fairy-wrens also spent more time scanning their surroundings and less time foraging compared to brown wrens.
This suggests that fairy-wrens perceive themselves to be at a higher risk of predation while bright blue and adjust their behaviour accordingly.
Intriguingly, fairy-wrens also adjusted their behaviour according to the colour of other wrens in the group. When a blue male was nearby, wrens were less responsive to alarm calls and devoted less time to keeping a look-out.
Perhaps this is because fairy-wrens view blue group members as colourful decoys in the event of an attack. This could occur if predators are biased towards attacking the most conspicuous animal, which reduces the predation risk for surrounding individuals. Brown wrens could also be taking advantage of the greater time blue males spend scanning, allowing them to lower their guard.
Being blue for longest gives males the best chance of attracting females, but they need to be extra careful lest they get eaten before it comes to that.
Coauthors on this research are Annalise Naimo, Niki Teunissen, Robert Magrath and Kaspar Delhey.
This is the ninth article in our Contested Spaces series. These pieces look at the conflicting uses, expectations and norms that people bring to public spaces, the clashes that result and how we can resolve these.
Head to a beach like Bondi on Christmas Day and you’ll share that space with more than 40,000 people. But we aren’t just jostling with each other for coveted beach space. Scuttling, waddling, hopping or flying away from beachgoers all around Australia are crabs, shorebirds, baby turtles, crocodiles, fairy penguins and even dingoes.
Beaches are home to an incredible array of animals, and sharing this busy space with people is critical to their survival. But, if we find it hard to share our beaches with each other, how can we possibly find space for nature on our beaches?
Here’s a classic example of how hard it is to share our beaches with nature. Head to a busy beach at dawn, before the crowds arrive, and you will most likely see a number of small birds darting about.
You may recognise them from the short movie Piper – they are shorebirds. As the day progresses, swimmers, kite surfers, dog walkers, horse riders, 4x4s and children descend upon the beach en masse, unwittingly disturbing the shorebirds.
Unlike seabirds, shorebirds do not spend their life at sea. Instead, they specialise on the beach: foraging for their invertebrate prey, avoiding waves, or resting.
There are few places you can let your dog run for as long and as far as it pleases, which is one of the reasons beaches appeal to dog owners. But this disturbance results in heavy costs to the birds as they expend energy taking flight and cannot return to favourable feeding areas. Repeated disturbance can cause temporary or permanent abandonment of suitable habitat.
The fascinating thing about many of these shorebirds is that they are migratory. Beachgoers in Korea, China, Indonesia or New Zealand could observe the same individual bird that we have seen in Australia.
Yet these journeys come at a cost. Shorebirds must undertake gruelling flights of up to 16,000 kilometres twice a year to get from their breeding grounds in Siberia and Alaska to their feeding grounds in Australia and New Zealand. In their pursuit of an endless summer, they arrive in Australia severely weakened by their travels. They must almost double their body weight before they can migrate again.
And these birds must contend with significant daily disruption on their feeding grounds. A recent study in Queensland found an average of 174 people and 72 dogs were present at any one time on the foreshore of Moreton Bay, along Brisbane’s coastline. And 84% of dogs were off the leash – an off-leash dog was sighted every 700 metres – in potential contravention of regulations on dog control.
Managing the menagerie
One conservation approach is to set up nature reserves. This involves trying to keep people out of large areas of the coastal zone to provide a home for nature. Yet this rarely works in practice on beaches, where there are so many overlapping jurisdictions (for example, councils often don’t control the lower areas of the intertidal zone) that protection is rarely joined up.
However, our work at the University of Queensland shows we don’t need conservation reserves in which people are kept out. Quite the reverse. We should be much bolder in opening up areas that are specifically designated as dog off-leash zones, in places where demand for recreation is high.
In the case of Moreton Bay, 97% of foraging migratory shorebirds could be protected from disturbance simply by designating five areas as off-leash recreation zones. Currently, dogs must be kept under close control throughout the intertidal areas of Moreton Bay.
By zoning our beaches carefully, the science tells us that the most intense recreational activities can be located away from critical areas for nature. And there’s no reason why this logic couldn’t be extended to creating peaceful zones for beach users who prefer a quiet day out.
By approaching the problem scientifically, we can meet recreational demand as well as protect nature. Proper enforcement of the boundaries between zones is needed. Such enforcement is effective when carried out in the right places at the right time.
We believe that keeping people and their dogs off beaches to protect nature is neither desirable nor effective. It sends totally the wrong message – successful conservation is about living alongside nature, not separating ourselves from it.
Conservationists and recreationists should be natural allies, both working to safeguard our beautiful coasts. The key is to find ways that people and nature can co-exist on beaches.
You can find other pieces published in the series here.
Madeleine Stigner, Research assistant, The University of Queensland; Kiran Dhanjal-Adams, Research Associate Ecological Modeller, Centre for Ecology & Hydrology, and Richard Fuller, Associate Professor in Biodiversity and Conservation, The University of Queensland