On the north coast of NSW (New South Wales) in Australia, in a small regional area called Tuckurimba, local resident Katrina Jeffery spends an hour each morning on her quad bike checking the trees on her property for koalas. She has been doing this for over 4 years as part of her mission to help restore important koala habitat in the region. Katrina has an in-perpetuity conservation agreement with the BCT and now receives annual funding to continue her important work in koala habitat protection and restoration.
She runs field days for local residents to educate and encourage them to get involved in koala conservation, and even has her own website!
Knowing her from the facebook page
“Koala Gardens at Tuckurimba” and becoming interested in koalas and their
conservation, I visited Katrina at the beginning of September. It has been a unique
opportunity to understand better all the issues koalas and all wildlife are currently
She has been regenerating the habitat on her property over the last years with the help of a professional team. They have planted hundreds of trees many of which koala food trees. This has increased the stability of a koala colony with an increasing number of other koalas using it as a corridor.
I already knew the names of the koalas belonging to the colony of which in just few hours we got to see Bullet, an almost 4 year-old male and Stevie, a female with a joey just beginning to emerge from her mother’s pouch. Then we saw another koala, Julius, not yet belonging to the colony but not new to the Koala Gardens.
We visited Friends of the Koala in Lismore where we could see how busy they are rescuing injured and sick koalas, rehabilitating those in care, gathering fresh leaves for them, educating the public and many other things connected with koala preservation. We attended a presentation given by Lindy whose finger was wounded by of the bite of a rescued koala: a reminder that in spite of their cute appearance they are wild animals and only licensed and trained people should handle and rescue them when it is appropriate. Ordinary people should just report every koala sighting and above all call when they spot sick, injured or orphaned koalas that need to be rescued as soon as possible. Almost all of them are volunteers dedicating their free time to these amazing yet threatened creatures.
I also had the opportunity to meet Marley the first employed Vet Nurse. They are doing everything they can to preserve the koalas but the area they cover is huge, basically the Northern Rivers region up to the Queensland border to the north. For this reason, they need additional volunteers.
Katrina also took me to three sites where usually there is koala activity, in two of them we saw a koala: one healthy male and a girl with a joey. The other site, Tucki Tucki Reserve, used to be a 4 ha area populated by many koalas but Katrina hasn’t seen them for a few years now and we didn’t get to spot any, neither there were clear signs of recent koala activity (particularly we didn’t find scats): this was sad because it’s a viable habitat but there might be some reasons they are no longer there.
There are so many questions that are yet to be answered. As Katrina said “the more I know about them, the more questions I find that I don’t have answers to”.
In fact, you might think the koala is a
predictable and simple animal whose main occupations are sleeping and feeding on
eucalyptus leaves, instead they are indeed very complex marsupials organised into
a hierarchical and peculiar society. Each koala has his/her own home range and frequently
his/her own home trees with the alpha male and alpha female having the larger home
range overlapping the others. When they become independent from their mothers, they
often move from their original territories to find new ones they can call home.
Unfortunately, having more and more fragmented
habitat because of land clearing, urban sprawl and busier and busier roads, they
are facing many more dangers than in the past. Hence the high mortality rate due
to vehicle hits, domestic and feral dog attacks and stress-related diseases such
as chlamydia and koala retrovirus.
When in the trees they’re much less prone
to these risks whereas on the ground their lives are always in potential jeopardy.
Unfortunately, limiting their movements
with fencing is not a solution because it would create inbred population not genetically
diverse thus often weaker, more inclined to diseases. Moreover, it would prevent
other koalas from entering a safe and viable habitat. One could think that there
are plenty of trees in rural areas, but there are only three primary koala food
trees: Forest Red Gum, Tallowwood and Swamp Mahogany.
Then there are a dozen or so secondary koala
food trees such as the Paperbark and the Pink Bloodwood, but they’re just a fraction
of the hundreds of eucalyptus trees.
On Katrina’s property there are primary koala food trees and also secondary food trees. Many are self-sown, others have been planted and are used to supply the koalas in care at the Lismore Friends of the Koala centre. It’s amazing the quantity of leaves they need daily. To give the patients in care the best chance to heal, they provide them a wide variety of leaves of the highest quality.
But the habitat regeneration is not just
about koalas. On Katrina’s property there are now many vulnerable species. She has
put nest boxes on some trees for the little lorikeets, even though one is now used
by a family of squirrel gliders and another by a snake. It’s fabulous to see how
habitat can be regenerated and become home to a variety of native plants, herbs
My personal thought and little invite is
that many landowners should follow Katrina’s example restoring habitat on their
properties or at least a portion of them ensuring wildlife corridors crucial to
the survival of many species. It’s so rewarding and can make all the difference
for them but also for us in the long run.
A world without wild animals would not just
be very sad but also not hospitable for us. There is no turning back from destroying
an ecosystem and the consequences are going to hit us sooner or later. Watching
wild koalas living a peaceful life in the wild as it’s meant to be is so exciting
and totally different than just seeing them inside zoo precincts. And, think about
this, just a few years ago a koala was not a frequent occurrence on Katrina’s property.
maybe just two individuals in a month. Last month, Katrina recorded 20 different
individuals on her property.
It may seem a miracle but everyone living in the beautiful surroundings can make it happen.
In conclusion, I can’t thank Katrina enough
for educating me, answering my questions and sharing her passion that has become
a way of life making a positive impact for the koala, wildlife in general and, ultimately,
all of us.
Regenerating native habitat is usually achieved using two basic methods, and they are not exclusive. A great result is often achieved by using both together.
Planting saplings that either come from elsewhere or grown from seed on the property.
Encouraging and nurturing natural regeneration.
Koala Gardens now has 8 years of regeneration work to observe and compare and during this time both strategies have been used.
Planting of species as tube stock is the only option when you need to add species to the property that do not currently exist. One thing it is important to consider when choosing species to introduce is what habitat and species are endemic to the area. Unfortunately, in the past, species have been planted outside of their native area, thinking that if they are Australian they are native. This is not always true.
Knowing what is endemic allows you to plant the habitat that will quickly assist the correct ecosystems to be re-established or repaired.
Regeneration needs to focus on entire ecosystems, rather than thinking in terms of creating plantations. This will mean considering the under-storey, mid-storey and top-storey with the flora, and considering the fauna that will be involved from insects through to the larger mammals, reptiles and birds.
Plantation thinking often results in mono-cultures or out-of-area plantings that don’t support the local fauna as well.
However, what has interested me more in my observations is two main areas of difference I have observed in how natural regeneration trees behave and grow, and in how the koalas behave in response to them.
In order to reproduce a tree will flower and these flowers must be pollinated to produce viable seed. There are a range of animals that assist this happening from fruit bats, to honeyeater birds to bees and other insects. In eucalyptus trees the seed is contained inside gum nuts which protect the seed until it is fully formed.
Each mature eucalyptus tree may release tens of thousands of seeds in a single year. Some of the seed falls to the ground around the parent tree, and some may be born on the wind to fall some distance away.
If conditions are right, there could be hundreds of young seedlings that result. They may be sparsely positioned or there may be clumps of saplings. Not every sapling is going to grow to maturity for many reasons. However, as they are growing, there are many benefits to growing in a community.
Naturally sown saplings generally grow at a slower rate than saplings grown in a nursery and planted as tube stock, and are often much closer to each other than deliberate plantings.
The next article will discuss the pros and cons of slower growth, and following articles will address community living of trees.
The constant balancing act a koala is involved in while feeding, goes way beyond what can be seen. The koala analyses the leaves to ensure they contain enough water and not too much toxic eucalyptol.
Eucalyptus leaves are very high in fibre, which means the koala’s stomach fills up quite quickly. If they were also high in calories, then a nice full stomach would mean fuel to give them energy.
However, because eucalyptus leaves are low in calories, they feel full quite quickly, and they also feel tired.
I have often observed a koala actively awake and eating, then reaching a point where it will literally fall asleep where it takes in the last leaf. It always appears that they eat until they can fit in no more and the need to sleep overtakes them.
To complicate the choice of leaves to eat, the chemical composition of leaves on any given tree is not a constant, but a variable. Many factors affect the composition of the leaves such as weather events, seasons, insect loads, disease, soil events and amount of browsing.
Adding to the complications is the fact that you cannot tell a ‘good’ leaf by looking at it. What this means to the koala, is that even though it has trees it knows in its own home range, they need to be analysed at every meal.
Koalas are not looking for the youngest, softest, greenest, brightest, freshest leaf or tree. At times, certainly a koala may eat the youngest tips ravenously, but that does not mean only young tips are preferred.
Many times I have seen koalas eating leaves that appear old, dry and even spotted with brown areas. At other time I see koalas plucking only the leaf, yet another time they eat a large amount of the stems.
I have also observed, with my daily record keeping of koala movements and use of trees on the property, that some trees are only used seasonally. This is not a consistent occurrence in itself. Some trees of the same species and a similar age (mature trees at least 50 years old), are used year round, some are used only at one time of the year, and some another time of year. There is nothing for the human eye to see that would indicate why this is so.
This supports the research, showing that koalas do stop and smell the leaf and analyse what to eat when. This is more intricate than choosing a tree or leaf for the taste, or to obtain a varied diet.
In order to cope with the low calorie content of their food source, the koala has a lower metabolic rate of about half that of most mammals. This is significantly low.
The result that we observe is that koalas spend 18-22 hours a day either sleeping or at least resting, so that their digestive system can work on the leaf they have eaten.
Even though koalas are often thought of as nocturnal, this is not strictly true. Koalas will wake at any time of the day or night and move about and eat as needed. They eat when their stomach empties, and sleep or rest to digest. They are most likely to have their most active period during the night, and most likely this will be in the early hours of the morning before dawn.
Koalas are specialist folivores. This means they eat a diet consisting of leaves, and in this case they have a narrow range of leaves that they are able to eat. Some people say koalas are ‘fussy eaters’, but the reason for their particular choices of which tree, and then which leaves in the tree they will eat, is fascinating.
We often think of the koala as being a laid back, relaxed, easy going creature, living a life of ease. This perception comes from putting a human interpretation on their postures and the amount of time they spend resting and sleeping.
The eucalyptus leaf, if studied closely is tough, abrasive and toxic. Have you ever plucked one of these leaves and felt it with your fingers?
The koala must put a lot of effort into grinding the leaves with their molars. The amount of wear on the molars is the most accurate way we have of determining the age of a koala. The wear on the teeth continues as the koala ages, and if the animal remains healthy and lives to an old age, their teeth may wear down so far they become unable to eat.
It is fascinating to see that an animal that has a limited primary food source has actually adapted to living in a diverse range of habitats, and across such a range of climates. The koala is found living in tropical and subtropical areas of QLD, and yet also in areas around Canberra that snow in the winter, and even some of the drier areas of Victoria. We observe certain basic differences in the appearance of the northern and southern cousins, yet they are the same species.
Across this range of habitats there are around 14 eucalypts that are considered their primary food sources. Yet in nearly every area koalas live, there are usually only around 3 of the primary species that the koalas use in that area.
They are observed to feed from around 30 non-eucalypt trees, but again the species used vary from region to region.
Each eucalypt leaf contains a wide range of ingredients, including the things we would expect such as protein, complex carbohydrates and water.
They also contain high levels of tannin, tough fibres, oil and cyanidic substances (which convert into cyanide). Yikes, that sounds like a mouthful of poison doesn’t it? It certainly is, to most mammals, and you can be sure it even tastes that way as well.
It is interesting to note that when we pluck a eucalyptus leaf from a tree, we can tell very little about it’s make up without taking it to a sophisticated laboratory. It feels tough and a little dry, because they have a rough surface, but it actually has a high water content – often at least 50%. This means around half the food the koala eats, is actually water.
Most animals could not survive the toxicity of the eucalypt leaf diet, and even the koala has to be careful they to not exceed certain levels of eucalyptol (the main component in eucalyptus oil).
So how do they make sure they can cope with their diet?
Koalas have the ability to chemically analyse the contents of the leaves by smell. That huge nose is like a portable laboratory. If you get the chance to watch a koala feeding in the wild, you will notice how often they smell leaves before eating. This is a constant balancing act they must perform.
Pap – one dictionary definition of the word in general is “bland soft or semi-liquid food such as that suitable for babies or invalids.”
Koala mums don’t have the luxury of a supermarket and kitchen to prepare those first baby meals for their joey of course.
The koala digestive system is unlike that of most other animals. We know that koalas eat leaves. Do you also know that a joey drinks mum’s milk and nothing else for around 6 months while developing in the pouch?
Most animals that digest leaves and grass have 4 stomachs, and these animals are called ruminants. Cows, sheep, goats, giraffes and kangaroos are some of the most common ones you might think of.
However, some animals that eat leaves have only one stomach, and they use a really big caecum to do this (that’s the appendix in us, which is tiny). They are called ‘hindgut fermenters’. Horses, rabbits and koalas are common animals you know that are in this category.
The caecum and the large intestine are filled with microbes that turn it into a big fermentation vat. This fermenting happens in the extra stomachs of ruminants and they are also called ‘foregut fermenters’.
It’s the microbes that are of most interest here. Other articles will cover more about digestion. Joey has been living a very sheltered life inside mum’s pouch, and has been drinking only her milk. The microbes joey needs to digest leaves are not found in the leaves, so joey needs to get them from somewhere. A goat kid will begin nibbling dirt within hours of birth and so begins to get microbes into their digestive system. Not the case for the koala, as joey is still very fragile and high up in the treetops.
So mum has to provide the microbes joey needs to ready the digestive system for those tough eucalyptus leaves.
Joey knows when the desire to eat begins, and puts its head out of the pouch and begins to nuzzle around mums cloaca. (koalas have a single opening like birds and so it has the same name as we use for birds) This nuzzling and licking stimulates mum to begin to secrete a pasty liquid directly from her caecum for joey to eat. Koala faeces is shaped into firm pellets, but pap is a pasty semi-liquid. It is really quite similar in texture to a puree made for a human baby just starting to eat. However the reason is to kick start the hindgut in the fermentation process rather than to provide nutrition. You could say, pap is a probiotic infusion.
We usually say that pap is a special faeces, but it is actually contents of mum’s caecum. Probably not a big distinction for most people, but there is a difference. Mum’s only produce the pap for a week or two at most while joey stimulates her. Joey knows when it is no longer needed as joey starts to feed on leaves and is able to easily digest them.
Scents are important to koalas and their sense of smell is highly developed. We are all aware that they have large noses dominating their faces, and that is not coincidental.
The sense of smell is used for two main purposes – communication and chemical analysis of a potential meal. In both cases the ability to conduct a degree of chemical analysis is involved. This means the koala olfactory ability is above most mammals.
Koalas are solitary animals, yet they do live in a colony. This means they recognise the other colony members, and therefore distinguish koalas that are strangers. They are highly unlikely to do this by sight because their solitary arboreal nature means that they may not really ‘see’ each other often. They do however recognise the smell of other koalas. They also recognise the bellow of other males.
Most of the time however, koalas are quiet. Yet a koala does not move through the territory of another koala unnoticed, even if it makes no vocal sounds.
How does one koala know it is moving through another koala’s territory you might ask? How does a regular colony member know another koala has been in their territory?
We observe that both sound and scent are used to communicate more during the breeding season – a time when koalas are actually communicating the most. However, koalas have a home range within their colony area and they have home trees within their home range.
How does one newcomer know a tree ‘belongs’ to another koala? It must be by some method that humans are not aware of unless they were to be come a scientist (even a citizen scientist) and begin to study what is going on.
A terrific thing about using scents to communicate is that it is not directly threatening, and it conserves energy. Koalas will use both scent gland and urine to mark territory, but the messages they leave behind are probably more complex than simple ownership.
Whenever we observe a koala moving on the ground from tree to tree, we notice the koala will take some leaps and bounds, then stop and smell the ground and shrubbery at intervals and so on.
Every koala has a subtle difference in the chemical composition of their smell, making their own scent as unique as their fingerprint. Colony members remember this individual scent because they not only smell it once, but they smell it in layers if you like. A tree will be marked with scent whenever the koala enters and exits the tree. This builds up these layers of scent. These layers add a lot of meaning to the scent as they advertise clearly that a particular koala owns a tree, or uses it frequently. A koala can also tell how recently the scent was left and so have some idea of whether the owner of the scent is likely to be about.
A male koala will rub his scent gland over trees belonging to other koalas in order to leave an indication that he passed through in a similar way to other mammals that use urine to mark territory and indicate their availability for breeding.
When out in the bush even you can sometimes ‘smell’ a koala about, particularly during the breeding season.
While only males have scent glands, and only mature males have well developed glands, all koalas have a highly developed sense of smell.
As mentioned previously, hearing is more than the physical process of vibrations being perceived inside the structure of the ear. Hearing is also about interpretation of those vibrations, and the how brain filters the vibrations our ears physically perceive. (How the brain filters and makes sense of what we, and in this case the koalas, hears.)
The history of the koala as an arboreal (tree dwelling) animal with little predator threat has influenced their hearing filters and reactions to what they hear. From the heights of the treetops, koalas filter out noises such as cars and other motorised vehicles going past. Roads encroach so much koala habitat that many koalas find themselves sleeping in places where there is almost constant vehicle noise.
Have you ever driven along a busy road and seen a koala fast asleep in a tree right beside that road?
By the same filter, a koala does not really differentiate between the sound of a car, chain saw, mower or bulldozer.
The koala has no way to figure that the bulldozer is going to knock down the tree it is in, when thousands of cars and other machinery have gone right past without incident.
In the same line of reasoning, the koala does not perceive they are in the direct path of the car approaching, when it is down on the road. The car sounds the same as the cars that went right past the tree all day long. The koala does not have the kind of executive thinking to figure that this spot on the ground is the place the cars were.
I have often seen a koala look up and watch me approach on the quad bike however. In nearly all instances the koala was already awake, and actually sees my face, and sees me looking intently into the tree. Any koala that has not become very accustomed to my presence will react to me, rather than the quad bike, and specifically to me looking directly at it.
I have tested this by looking away and riding past the tree, then looping back around and being sure not to directly look at the koala or the tree. The koala will nearly always relax, at least to some degree.
I always obtain a much bigger response if I approach the tree on foot.
An individual koala will have variations to their hearing filter depending on the particular habitat they live in and what is normal there. This means a koala that lives in a forest that is isolated from roads completely may respond differently to machinery noise if it is something they do not normally hear at all.
I have been fascinated by how koalas respond, or do not respond, to sound, when I have been out koala spotting.
It would appear that koalas have a decent ability to hear. They have large, mobile ears and when awake I have found they can hear footsteps, twigs snapping or voices quite acutely.
However hearing is more than the mechanics of the ear perceiving vibrations. Hearing is also the brain interpreting those vibrations.
I have mentioned in other articles here that koalas are neither prey nor predator animals. If we consider this when observing koala behaviour in relation to hearing, it does shed some light.
Prey animals need to be alert as much of the time as possible, and they will particularly need to be alert through their hearing when they are resting and sleeping.
Predators need their hearing for hunting. They may need to hear smaller animals moving through dense bush for example.
Koalas also become familiar with sounds in their own home range and learn to filter out sounds that their experience tells them is not a threat. This is important in understanding that hearing is as much the brain interpreting sounds as the ear detecting the vibration. I have researched this topic and found little, so have conducted my own research with the koalas here in my daily spotting.
Compare the posture and expression on Legion in the video above to Pinky in the photo below and you can see the difference in response to sound, through being familiar with the sounds.
An observation I have made with many different koalas over a range of years is that I can elicit a strong reaction from a koala that is new to the property with certain sounds such as pretending to sneeze, cough or even growl. However, with repetition, over a period of time, the reaction will decrease and for many koalas the reaction will completely cease. This means a koala that arrives at the property may startle and stare at me, then move up the tree if I approach and make a sneezing noise. If I repeat this each time I approach on different days, it may take as little as 3 or 4 days for the koala to completely ignore the same noise. Some koalas take longer to reach a point of ignoring me, but I have noticed that every koala will have a significantly reduced response within 3 or 4 days of me approaching and making a particular noise.
There are however, some types of noises they will always respond to, such as stomping footsteps approaching the base of the tree, particularly if long grasses are rustled and twigs snapped. Even though koalas are not truly prey animals, there is an instinct to understand that anything that can make heavy footstep noises, and is approaching the tree, is a possible threat.
This does not mean that the footsteps are the loudest noise, at the time. I have often witnessed a koala ignoring the sound of the quad bike approach the tree, but jumping from the bike to the ground and stomping has brought the head up immediately. The bike motor had obviously been making a far louder noise, yet had been ignored.
The next article will discuss koalas and machinery noises, as this becomes important in understanding another layer of why they are at such risk with cars.
Koalas are often killed by cars in towns where the speed limits are much lower as well as out of town on higher speed roads.
One issue for koalas coping with roads in an urban area, is that there is more happening to distract the koala and the person driving the car. The koala has to process a variety of stimuli such as electric lights, dogs barking, children noises, other machinery or traffic, humans and animals walking about and probably an extremely fragmented home range. A car approaching, even at only 60kph is probably just a part of the cacophony around them.
In these situations koalas often simply step onto the road directly in front of a car apparently without seeing it was there at all. This is not because of poor eyesight, but because they cannot separate and deal with all the stimuli. Think of it like very young children playing and how unsafe that is near the road because we know a young child is likely to become so focused on play they will not see a car approaching. In a similar fashion koalas just focus on where the tree they need to get to is, rather than what may be in between them and this destination.
Koalas are often seen walking along a road (rather than across), or they are reported to simply stop and sit in the middle of a road and watch a car approach and stop in front of them. Observing koalas, it would appear that their flight response is often very low as they don’t have a ‘sense of danger’. This is discussed in the article on dealing with cars in more detail.
When the flight response is elicited in a koala they commonly give a leap in the opposite direction or any random direction and begin to run without checking to see if they have chosen a safe direction. They will then attempt to run to anything that looks like a ‘tree’ structure. In other words, something they can climb. This makes sense because their brain tells them that getting up high is the safe response. Once a koala rushes up a structure in fright it tends to then determine to stay there until well after dark.
Hence we see koalas sitting high up telegraph poles, on fences, or even veranda posts seemingly unwilling to move. The more stressed that koala becomes, the less likely it is to come down.
This is the typical koala response:
react without thinking and get up high
stay very still until late at night when all is very quiet
Roundabouts provide another level of complexity that is nearly impossible for a koala to cope with. All the koala sees is their food tree on the other side and they attempt to move towards it.
It is up to us as drivers to take more notice of wildlife on the roads, as the wildlife are not going to learn our rules.