Pap for a joey

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?

Wild koala and joey that has head out of the pouch ready to eat pap.
Joey with head in perfect position for pap feeding.

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.

Wild koala mother and joey in this photo. Joey has head out of the pouch and is eating pap for the first time.
Joey is eating pap.

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.

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What do koalas hear?

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.

Photo taken on the first day Pinky was seen on the property.
Pink’s first day here and she is very alert to sounds as nothing is familiar.

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.

Mist peering at the camera after been awoken by stomping footsteps.
I had to make stomping noises to get Mist’s attention as she is very familiar with me.

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.

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Koalas, cars and the urban setting

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 spend most of their time sleeping and digesting. When they move they are focused on where they are going, not on what is around them.
Koalas spend most of their time sleeping and digesting. When they move they are focused on where they are going, not on what is around them.

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:

  1. ignore everything
  2. react without thinking and get up high
  3. 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.

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