citizen

Hollows as Homes

This is a guest post by Dr Adrian Davis, Hollows as Homes coordinator and Research Associate at the University of Sydney. 

In urban and agricultural areas large, hollow-bearing trees are in decline, but many species of animal rely on them. In Victoria, hollow-using species include at least 31 mammals, 60 birds, 38 reptiles, 15 frogs and many insects (such as bees). Of these, at least 33 species are listed as threatened with extinction. This is why the ‘loss of hollow-bearing trees’ has been listed as a key threatening process nationally.  Hollows as Homes is a citizen science program asking you to report hollows in your local area, and the wildlife using the hollows – but more on that later.

Farms and agricultural areas are often characterised by large, old, isolated trees, or small clusters of trees. These clusters often act as ‘stepping stones’ and can be vital in linking up other small patches of trees on adjacent farms, allowing wildlife to more easily move throughout the landscape. Even a single standing tree with a hollow can provide valuable habitat and provide a nest or roost for an animal that would otherwise not be able to live on that farm. A good example of an animal that depends on clusters of trees on farms is the superb parrot, listed as vulnerable to extinction, which uses paddock trees for nesting, feeding, perching and protection. Retaining existing hollow-bearing paddock trees, ensuring that younger paddock trees are maintained so that they form hollows, and gaining a greater understanding of how wildlife use paddock trees is vital to maintaining wildlife in our agricultural areas.

Cut in hollow for small bird. Photo: John Martin.

Cut in hollow for small bird. Photo: John Martin.

 It’s not just on our farms that hollow-bearing trees play an important role, but within the bush and urban regions as well. Large, old trees - those most likely to contain hollows - are rare in urban areas. If you’re lucky, your local park or street may contain one of these trees; a grandparent of the bush. If you’re even luckier, this tree will contain hollows, although this isn’t guaranteed. In general, our urban areas contain young trees; however, it is likely that many of the species planted will never form hollows, or be allowed to form hollows for reasons of public safety (in case the tree falls). Urban bushland typically contains only half the number of hollows that are present in bushland outside metropolitan areas, and there are fewer hollows in urban parks and streets.

Importantly, not all hollows are the same, and some species prefer particular types of hollows (for example, a deep hollow, a hollow with a small entrance, or a ‘pipe’ style hollow). When we lose the hollow-bearing trees, we also reduce the number of different types of hollows, which can result in competition between wildlife, with some species losing out to more dominant species, such as the rainbow lorikeet taking a hollow from the eastern rosella. It has been shown that there are more aggressive interactions at hollows in urban areas than there are in natural bushland.

Hollows as Homes aims to increase the knowledge and understanding that we have about tree hollows: the distribution of tree hollows, the types of hollows available and how wildlife use tree hollows, including nest boxes and cut-in hollows. In areas lacking natural tree hollows, supplementary hollows, in the form of nest boxes or cut-in hollows, are often provided. However, the effectiveness of these alternatives is still not entirely understood. To help us understand more about how wildlife use tree hollows, nest boxes and cut-in hollows, we are asking people join in the Hollows as Homes program.

Choose a tree in your garden, street, park, bush or paddock that has a hollow or a nest box and report it through the website (this also works as a web-app on your phone). You can provide details about the tree and hollow, such as tree height and the direction the hollow is facing. Ideally, the hollow is in a location that you periodically encounter, such as while walking the dog or sitting in your garden. This provides occasional opportunities for you to observe wildlife using the hollow. If you see that any animals or insects are using the hollow, you can add these observations to your original report of the hollow through the website.

Galah at nest in tree hollow. Photo: J Turbill (OEH)

Galah at nest in tree hollow. Photo: J Turbill (OEH)

In addition, people can participate as a group, designating an area that they regularly visit and collectively assessing the trees for hollows and adding wildlife observations. The group option is ideal for bushcare sites, landcare programs, parks, schools, golf clubs, community gardens, and many more. An unlimited number of people can participate in a group, and, importantly, anyone who is part of the group is able to both view and add wildlife sightings to any of the reported tree hollows or nest boxes within the group boundary.

The information reported through Hollows as Homes will be accessible to the public, especially to land managers. Ideally, this information will inform conservation planning to conserve habitat trees and the provision of supplementary habitat, as well as our understanding of exactly which species are inhabiting our own backyards.

For information on how you can be a part of this program, visit the Hollows as Homes website or Facebook page. Alternatively, you can email Dr Adrian Davis for more information.

Hollows as Homes is a collaborative project between the University of Sydney, the Royal Botanic Garden Sydney and the Australian Museum. It is supported by funding from the Australian Government.

Cover image by Simone Cottrell. 

A count that counts

If you’re reading this article, chances are that you’re an environmentally aware person and have a sense of custodianship over your local environment. Perhaps you regularly volunteer for your local conservation group. Perhaps you want to do more to help the environment but don’t know where to start. Perhaps you want to help the environment but making a start is too much effort given your current work and family commitments. Well, BirdLife Australia’s Aussie Backyard Bird Count is the perfect solution to your volunteer fatigue/uncertainty/lethargy. You could be making a positive contribution to conserving our birdlife without leaving your property. What’s more, collecting the data involves only a bit of fun bird watching. What could be easier?

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  Superb fairy-wrens are a common sight in many Melbourne gardens. The Aussie Backyard Bird Count will help ensure they stay that way.  Image: Rowan Mott

Superb fairy-wrens are a common sight in many Melbourne gardens. The Aussie Backyard Bird Count will help ensure they stay that way. Image: Rowan Mott

There are many positive reasons why you should participate. This is a nation-wide initiative and 2016 will mark the third time this annual event has been run. Large scale programs such as the Aussie Backyard Bird Count are rare when it comes to the collection of biological data. Studies extending across geographical regions and annual timeframes have a much greater capacity to detect environmental changes that would be missed by studies that are site-specific `or focus on a single point in time. You may have read our recent article outlining the valuable insights gained from long term monitoring in the Grampians. Imagine the insights that could be gained if long term data were available at the national scale rather than at a single site. This is what the Aussie Backyard Bird Count promises.

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  Common blackbirds are an introduced species, but information on where they occur is still valuable for determining the health of Australia’s bird assemblage.  Image: Rowan Mott

Common blackbirds are an introduced species, but information on where they occur is still valuable for determining the health of Australia’s bird assemblage. Image: Rowan Mott

A similar program, Garden BirdWatch run by the British Trust for Ornithology, has been instrumental in monitoring the changing fortunes of the humble house sparrow. The UK population of house sparrows has fallen by approximately half in the last four decades. Considering there is estimated to be around 13 million house sparrows in the UK, that’s a lot of birds to have disappeared. However, there is no guarantee that any single study would have been able to detect this decline because the disappearance of sparrows at a single location or a single point in time may have been the result of small scale movements or a local population decline. It is only when the population as a whole is considered that the trend becomes worrying. There is good news for house sparrows, though. Recent data shows that the population appears to have stabilised in recent years thanks to milder winters and a growing number of people providing the resources sparrows need to survive in their backyards. Could you imagine if our very own superb fairy-wren, a bird as familiar to us as the house sparrow is to UK residents, underwent a similar catastrophic decline and we failed to notice? The Aussie Backyard Bird Count will ensure that we are better placed to detect such a change as well as less obvious ones.

If your backyard is full of introduced species, such as common blackbirds, spotted doves and common mynas, and you think that any information you might be able to provide is worthless, think again. Many invasive species may outcompete their native counterparts, and, consequently, monitoring the presence and abundance of introduced species is also valuable for conservation.

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	mso-fareast-language:ZH-CN;}   Rainbow lorikeets were the most commonly reported bird in last year’s Aussie Backyard Bird Count. Will they be again this year?  Image: Rowan Mott

Rainbow lorikeets were the most commonly reported bird in last year’s Aussie Backyard Bird Count. Will they be again this year? Image: Rowan Mott

Think your birding skills aren’t up to the task? Well, what better place to learn than in your own backyard where you’ll be able to hone your skills on a small subset of species. Moreover, these species will likely visit with some regularity, giving you plenty of opportunity to reinforce the important identification features.

If all that wasn’t enough to motivate you to participate, BirdLife Australia is also offering some fantastic prizes, including a top-of-the-range pair of binoculars. So there you have it, you have no excuses! Go to the Aussie Backyard Bird Count website and register as a counter. Then all you have to do is spend 20 minutes in your own backyard watching birds between 17th and 23rd October, record your observations, and sit back and feel the warm glow that comes from knowing you did a good thing for Australia’s birds.


Rowan Mott

Rowan is a PhD student studying seabird ecology. When he's not thinking about the ocean, he likes to think about woodland birds. 

Check him out on Twitter at @roamingmoth

Are artificial lights driving microbats.... batty?

This is a guest article by ecologist Grant Linley.

Their looks are the stuff of nightmares, they are continually urbanising and colonising new environments, and they have had disastrous impacts on the environment so far. These thoughts might go through the brain of Microchiropteran bats when thinking about humans. Whilst some may reel at their looks, their uniqueness makes them quintessentially Australian. These small, flying mammals are all around us at night and they live unheard and unseen among us. Insectivorous bats are a diverse and adaptable group of mammals that has been able to persist among environments that have undergone large scale changes due to urbanisation, making them a true Aussie battler.

Insectivorous bats are known to eat up to half their body weight in insects each night, with some eating up to 600 mosquitoes a night. Not only do they play an important role in keeping invertebrate species in balance, but in doing this they also promote plant growth and pollination. This makes them a key species in keeping urban ecology in balance. To help understand what affects insectivorous bats within urban environments, I conducted a study that considered the impacts of artificial lighting in Melbourne’s south-eastern suburbs. Using an Anabat Express (a gadget that helps us listen in on bat vocalisations), ultrasonic calls were recorded and used to identify species in artificially lit and unlit areas.

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    The Gould’s wattle bat ( Chalinolobus gouldii ) smiles for the camera. The study found that they were the most common species to occur along Bayside’s foreshore.  Image:   Lindy Lumsden

The Gould’s wattle bat (Chalinolobus gouldii) smiles for the camera. The study found that they were the most common species to occur along Bayside’s foreshore. Image: Lindy Lumsden

 

HOW DOES ARTIFICIAL LIGHTING AFFECT BATS?

Within the coastal vegetation in the Bayside area, I found unlit sites to have higher numbers of calls and species richness when compared to lit sites. Almost all of the identified species were adversely impacted by artificial lighting, specifically Austronomous australis, Chalinolobus morio, Miniopterus schreibersii oceanensis, Mormopterus spp, Myotis macropus, Nyctophilus geoffroyi, Saccolaimus flaviventris, Vespadelus darlingtoni and Vespadelus regulus. Lit sites attracted bats at lower temperatures than unlit sites and bat activity remained active throughout the night at unlit sites. However, at lit sites bat activity quickly diminished in the hours after sunset.

The effects of artificial lighting on insectivorous bats are complex and likely to be caused by a variety of reasons. All species that are susceptible to artificial lighting, except V. regulus, have larger bodies that are less manoeuvrable. It is thought that a lack of manoeuvrability may force these species away from lit areas, as they are not able to capture prey that is attracted to the lights. It is possible that artificial lighting causes changes in activity of bats at different temperatures because it interferes with insect navigation systems, making insects active at lower temperatures and in turn attracting bats during these times. The difference in bat activity throughout the night is thought to be caused by a rapid decrease in insect density around light sources as time passes after sunset, which forces bats to go in search of their prey in unlit areas.

 

WHAT CAN YOU DO FOR THEM?

Artificial lighting on the foreshore in the municipality of Bayside has impacted bats and appears to fragment parts of the landscape. The negative impacts on insectivorous bat activity will likely increase as more street and safety lights are installed in urban areas. In the future, safety lighting systems should be installed in car parks and walkways that are activated by a sensory switch and only remain on for a short period of time. Councils should also consider minimising the use of mercury vapour lighting, which attract larger insect loads than low-pressure sodium lamps. Additionally, members of the local community can build and install bat boxes, which provide bats somewhere to roost. Unfortunately, suitable habitat for these species is constantly diminishing within suburbia. These findings will be published shortly.

Banner image by Scott Sanders (via Wikimedia Commons).


Grant Linley

Grant is an ecologist interested in Australia's flora and fauna. He has experience researching, trapping, tracking, identifying and handling different Australian species. Whilst experienced in terrestrial Australian ecology, he has also conducted research in Borneo and South Africa. Grant's interests centre on preserving and reintroducing extant and extinct Australian species as well as using natural predators to control mesopredators.