building a nestbox for brushtail possums

	A Tweed Valley Wildlife Carers Factsheet
	A Tweed Valley Wildlife Carers Factsheet



This factsheet contains information sourced from members of Tweed Valley Wildlife Carers, members of other groups, independent advice, and research. We hope you find the information below useful, and it helps to answer your questions on this subject. If you have any further questions, please feel free to contact us on the email link below left.

BRUSHTAIL POSSUM Trichosurus vulpecula

Photo: Courtesy W.A.R.P Young Brushtail Possum

HABITAT These common visitors to our parks and gardens preferred habitat is dry eucalypt forest where they feed, mainly on leaves, and live in tree hollows. Found across Australia, various subspecies (such as the Mountain Brushtail - or Bobuck - and the Coppery Brushtail) exist in different locations.

BREEDING Brushtails give birth to a single young in autumn or spring which lives in the pouch for 4 - 5 months before riding on Mum's back. Mortality is high once the young brushtails leave to establish their own home range. The majority of brushtails killed on our roads are young males leaving home.

NOTES These are the possums that sometimes move into our homes. Brushtails are very adaptable animals, and in the absence of suitable hollows, will nest in roofs and walls. Relocation is not the answer... To find out why, visit our Living with Possums fact sheet.

Leading a largely solitary life, brushtails are very territorial, defending their range with deep guttural coughs and sharp hisses.

(1) INTRODUCTION

Natural tree hollows form when fungus and termites eat out the dead centre of old trees. Most Eucalypt species do not form these hollows until they are at least 100 years old. Although there are vast tracts of native plantation timber (particularly on the East Coast), they are typically harvested at around 60 - 80 years old. So of course hollows do not form.

Since European settlement, literally millions of trees (and hollows) have been lost to urbanisation, industry, roads, and agriculture. As if that isn't bad enough, our struggling native animals have to compete with introduced Honey Bees and Common Mynas, which aggressively colonise hollows.

These factors have led to some pretty desperate little critters trying to live in somewhat 'B grade' accomodation. Some examples are: Sugar Gliders trying to live in the fronds of Banana trees, Feathertail Gliders turning up in the electricity boxes on top of power poles, Microbats trying to sleep in mailboxes, and our seldom seen little Antechinus' trying to raise their babies in sock drawers, and even kitchen stoves.

Far from ideal... Many of these animals of course turn up in care.

(2) BENEFITS OF NESTBOXES

Although we cannot possibly hope to replace the countless natural hollows lost in the bush, our towns, cities, and farms were once forest. As a result, there is an awful lot of displaced wildlife competing for an ever decreasing amount of this prized real estate. This is where we can all really make a difference; in our suburban gardens, and rural properties.

A single well placed nestbox which survives say 10 years, can see a pair of Rosellas raise 10 generations of chicks. A slightly different box could provide a secure home to 6 adult Sugar Gliders. Different shape again could provide a luxury home to that 'trouble-some' Possum in your roof. Whilst yet another shape provides five star accomodation for up to 50 Microbats. And, when you consider that a single Microbat can consume one half it's own weight in insects a night. That's an awful lot less crawlies in your veggie patch. And, they provide this service completely free.

Nestboxes also provide priceless education for your children. Watching wildlife on TV is wonderful, but there is something very special about watching native animals coming and going, feeding, and raising their young so close to your home. If you've ever seen a Mountain Brushtail Possum looking out of her box at dusk, Pink nose resting on front paws - you'll know what I mean.

I grew up in the UK. One year my Grandfather decided to put up a nestbox in a pine tree in our garden. Next Spring a pair of Blue Tits moved in, and every year without fail, we used to watch from the comfort (and warmth) of the dining room, as that pair of birds raised 4 - 5 babies. From just 3 metres away, we'd watch the parents feeding the fledgelings every few minutes, and seemingly just days later, watch the youngsters take their first tentative flights. What's more, the box only took 10 minutes to put up.

Nestboxes are fun, easy and cheap to make, and once up will provide a secure home for many years to come.

A word of caution: If you own a cat, putting up nestboxes which attract birds & mammals to your garden, is a recipe for disaster...

(3) CONSTRUCTION

Below is a plan for the construction of a nestbox suitable for Brushtail Possums. Materials used, and notes are below the plan. Please note that all sizes marked are for INTERNAL DIMENSIONS

The best materials for construction are either; 3 cm thick plantation pine (hardwood is a product of native forest), or structural pine plywood. There is of course no need to use expensive dressed timber. Rough sawn or even second hand timber is ideal. Just make sure if using second hand, that it is free of nails, and any unknown paint.

Your box is best screwed, rather than nailed together, and may be finished off with filler in any gaps, a coat of primer, undercoat, and lastly a dull acrylic finish.The roof can either be hinged conventionally, or simply make an outside hinge out of a piece of old rubber, which also helps to make it weatherproof.

A couple off offcuts on the inside of the roof to prevent slippage, and either mesh, or a few thin strips of offcut baton on the inside front to allow the youngsters to climb out..

VERY IMPORTANT: Drill a few 5mm drainage holes in the base. Young birds have quite literally drowned in non-drained boxes. And lastly: Throw a generous handful or two of wood shavings or sawdust in the bottom... and we're done.

(4) INSTALLATION

So you're now the proud owner of a new Brushtail Possum nestbox. Where to place it?

Aspect: Choose your position carefully. Think about which side of your house takes the brunt of cold wind, and driving rain. (how comfortable would you be with an open wall on that side?) Face the entrance away from prevailing winds, and make sure that the box will have plenty of shade during the hottest part of the day.

Hang from the chosen tree by a piece of wire threaded through a scrap piece of garden hose (so that it doesn't cut into the tree), or alternatively, nailed to the tree using 2 strips of galvanised steel. The strips need only go halfway round the tree to allow for growth, and to prevent ringbarking.

FOR BRUSHTAIL POSSUMS, you need to position the box at least 3 - 5 metres above the ground

OK. So your new nestbox is in place, and you're sitting back with a beer, or a cup of tea waiting for the homeless critters to move into their new home. Don't be disappointed or surprised if no one takes up residence immediately. It can sometimes take weeks, or even months, for someone to show some interest. There are many reasons for this:

The box is 'too new', unfamiliar. It looks and smells new and out of place. Give it time to 'weather in'. To become part of the local landscape.

Most birds for instance, nest in the spring. Birds don't normally live in nests, only requiring them for breeding. If your box went up in May, it may not be required until say October.

Mammals such as Possums do live in hollows all year round, but it's not until the parents actually kick the youngsters out of home, that junior will go in search of a new home.

While you're waiting for the box to be occupied, please resist the temptation to keep looking inside. You don't know who's checking the box out when you're not looking, and constant disturbance will only discourage them. You'll know when the locals move in by watching, listening, and by looking for droppings underneath.

Also, do not be alarmed if 'the wrong animal' moves into the nestbox. Hey, if an Eastern Rosella moves into the box you so carefully made for a Ringtail Possum... So be it. Obviously the Rosella's need was greater. Native animals will often move into the 'wrong sized' box.

(5) MAINTENANCE

To finish off, just a few words on maintenance. Once a year, just have a quick look to see if any repairs need to be done, such as filling any gaps, a quick re-paint, or making sure the box is still securely fastened to the tree. Also, watch that the growing tree doesn't pull apart the fastening.

BIRDS: Some introduced birds such as Sparrows, Starlings, and Mynas have become a menace; driving native birds away, or even building their own nests on top of existing eggs or young. Nest building by these species should be discouraged by removing nesting materials or eggs. If Indian Mynas are a continual problem, you may want to add a Myna baffle to the front of the box.

BEES: The introduced honey bee has also become a serious problem in some areas. They will readily colonise tree hollows (real or artificial). If you have a problem with bees, look up bee keepers in your Yellow Pages.

If you've taken the time to build and place a box like this... Pat yourself on the back. YOU WILL have made a difference to YOUR local environment. Congratulations.

A FINAL WORD: Once your new box is occupied, please resist feeding. Feeding native wildlife is not a good idea. It fosters familiarity with humans and domestic animals. It encourages a dependency on an artificial food source, which will stop if you go on holiday, get sick, or move away. And lastly, your feeding routine is soon 'sussed out' by local cats and dogs. Animals are at their most vulnerable whilst feeding, and are particularly at risk when instead of feeding high up in the canopy, they are encouraged down to your level. You just don't know who is watching from the bushes. (This includes bird baths placed near cover). Please don't encourage your new residents to become 'cat-bait'

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