Although koalas are solitary animals, they live in colonies. However, this doesn’t mean they “socialise” together in those colonies. This means the alpha male takes on a different meaning than what we usually think of. Outside the breeding season, the koalas who live in any colony may rarely see each other. Even those that do will probably never come into physical contact with each other. Each koala moves about in an area of their own which we call a home range.
In every colony it is possible to the divide resident koalas into ‘types’ in order to give a clear explanation of how colonies work. Basically, each colony will contain alpha males, breeding females, low ranking adult males, juvenile males and juvenile females.
A colony area is defined as the home range of the alpha male. This means that while koalas may always be found in a particular area, any ‘colony’ map will change over the years depending on the alphas using the area. Some ecologists talk of colonies in a broader way using areas of habitat as more of a definition.
How is an Alpha Male Koala Defined?
Alpha male koalas are definitely bigger and stronger than the other males around them. They are not however ‘in charge’ of those males the way an alpha male of highly social species might be. For example the alpha male chimpanzee displays a lot of grooming behaviour, physical exhibitionistic and dominance displays.
The alpha male koala is very different to this. They are still a solitary animal. Alpha males should not appear to be more aggressive than the other males, although appearances can deceive. They often look more aggressive because they may have a lot of scars, particularly on the face and ears.
Interestingly, these battle scars are as likely to have been caused by females they attempt to mate with as by males they are fighting with. The scars are not an indication that he is meaner or more aggressive than other males.
Characteristics
An Alpha male is characteristically calm and confident with a large scent gland. This gland becomes more prominent the older he gets. This is partly due to it being highly active and that he is constantly rubbing it on tree trunks. Of course, if this male is provoked, the fact they are larger and strong means they are a fierce opponent.
The alpha has a much larger home range than other koalas. For this reason, he must move further on a daily basis, scent marking as he goes. It is rare to see him in the same tree 2 days in a row unless there is a female he is intent on mating. He may sleep a little less than other males and needs to eat more.
Another meaning of alpha male is the one who is currently the alpha of an established colony. Take, for example, a young 3 year old male koala who is an alpha type. He is developing a strong scent gland and taking potential breeding opportunities. He disperses and looks for a new area that either does not have a strong alpha already, or one with an aging alpha that he may challenge.
Even if he loses the challenge with the first adult male he tries it with, that doesn’t mean he isn’t an ‘alpha type’. Some alpha males may spend years wandering nomadically if they are unable to find a home range where they can settle. They become the ultimate opportunists that can provide terrific genetic diversity.
Aging Alphas
On the other hand, an older alpha male, is going to encounter younger males that are keen to take an opportunity to best him. He may be defeated by a younger male who takes over his range.
Another example is the male that has been established as alpha for years in his home range. He begins to find his daily activities a little harder as he ages. He may become injured or diseased, and even if he recovers may not be as strong as he was previously.
However, it is not always as simple as throwing the old alpha out, The older male may stay and the new alpha may only take part of his territory. He may then expand this further in the next couple of years in any direction.
Both males are alpha males, but maybe one is now ‘semi retired’, maybe approaching the end of his life, and only moves in a smaller area. He may only stay in this position until the next breeding season when he may be challenged again.
The breeding season and dispersion season coincide and there is good reason for this – to increase genetic diversity. At the time females are becoming receptive to mating, the males are all stirring from the winter. At this time of stirring testosterone levels are rising. Males begin to move through the landscape dispersing and taking opportunities as they can.
How does a male develop or become alpha and is ‘alpha’ – purely genetics or is there a mix of nature v nurture/environment?
‘Alpha male’ is actually what we would call a character trait in humans. This means that some male koalas will never ‘become an alpha’. Even if there is no alpha in an area inhabited by other females and males, a low ranking male won’t simply ‘rise to the challenge’ and ‘become alpha’. He will probably get lots more opportunities to try and breed the females though!
So becoming an alpha is a real mix of nature v nurture. One alpha male may live a longer life with a large home range and strong colony due to nurture. Conversely, another may take on a less optimal area or suffer some injuries and be in a strong position for a lot shorter time.
Alpha males live a tough life. They may concede their home range to another younger alpha as they age if it is contested. Alpha male is a character trait. That is nature. However, nurture or environmental influences will certainly impact on how successful any one alpha male is during his lifetime.
Do alphas stay in one home range all their lives or move around?
An alpha that has established his territory will stay there for the bulk of his life.
Let’s take a fictional example to think about what a full life span of a healthy alpha could look like. This is without any impact of habitat loss and urbanisation.
Joey emerges from the pouch in his mother’s home range. While some young stay where they were born, most will disperse. This will be either when they separate from mum, or the following year when the breeding season starts. Some joeys will be taken to an area of habitat that is not in mums range and left there when it is time to separate from mum. In this case, they may well disperse twice.
Wattle as an example
Let’s take former Koala Gardens colony member Wattle as an example of this. We don’t know who Wattle’s mum is, he just ‘appeared’ here on his own as a newly separated back young. We don’t know if his mum brought him onto the property and then left as Katrina never saw her. She may have brought him close to here and he then found his way here.
The following year, as breeding season started, he began moving about the property in larger and larger loops, and then he moved on, or dispersed.
It’s pretty difficult to say any particular male will become an alpha when they are this young. Wattle was just starting to develop his scent gland in the couple of months before he left.
Young males develop the scent gland at around 18 months old, but they don’t reach full maturity until 4 years. If a young male is an alpha, he will have a well developed scent gland that is obvious by 2.5 – 3 years old.
Dispersing males
When the alpha disperses he has to search for habitat that is vacant. This means it either has no alpha in residence, or a declining alpha that is either aged, injured or diseased. Even a young alpha at this stage of 1.5 – 2 years of age is not going to start contesting an adult alpha. He may just settle in an area until he is 3.5 years. He may then decide he can’t contest the alpha in residence and disperse again to find a suitable place or weaker alpha to contest.
There are so many variables to each individual koalas life that we can’t say it goes like this, then this, then this. One young alpha may spend a couple of months searching and find somewhere suitable. Another may search for a year or more. Sadly, a number of these young males will meet with misadventure while searching for a home to settle. Some will encounter cars or dogs, or fighting with males that are superior.
In our example, let’s say the male finds a place to settle. He either wins a contest with the current alpha, or finds somewhere that has lost the alpha. He may now live here, confidently in this position for 4-8 years if he isn’t somehow injured or becomes ill.
As he approaches 10 years and passes this age, he may still be very strong, but the chances of his position being contested by a young 3-4 year old will increase every year.
As an aged koala he may be displaced and still live in that same area, but take a quieter approach to life if another wins the place of alpha.
The importance of habitat for Alphas
The more good quality habitat there is available, the less urgent the contesting for territory by males. However, this is a normal part of koala community life. Hence, there is always some level of contesting between males all during their lives. As the dispersion occurs each year, the dynamics of each colony changes. As males mature (and remember this takes 4 years), the colony dynamics change this way too.
Most ‘fighting’ between males does not have an intended outcome of death or forcing the other animal out of the area. For the most part, this behaviour simply resolves disputes on territory and hierarchy.
As habitat continues to decline, an alpha male may find himself wandering about for months or years, taking opportunities. This is because he couldn’t establish his own home range. The lower ranking males tend to find themselves somewhere to live ‘under the radar’ so they don’t tend to be the nomadic wandering big males.
Do males fight to establish who is going to be alpha?
Koalas are highly territorial. This means that in order for males in particular to establish and keep a home range, there will be some behavioural strategies used. These include fighting. However, fighting is not the first choice for any wild animal. Male koalas definitely do fight and engage in a lot of posturing and warning types of behaviour.
There are a range of strategies that they use:
Male scent marking with their scent glands and urine. This marking announces their presence clearly to all other koalas and has lots of information in it using pheromones. Each koala that comes along receives a lot of information. They don’t need to climb into the trees for this. Males will mark the base of the tree as well as mark parts of the trunk and branches.
You can think of the scent marking as like leaving messages on a community noticeboard.
Male koalas bellow, although female koalas can bellow and sometimes do, it is typically male behaviour and at night it can be heard for a surprising distance in the right conditions.
Many people say the bellowing is him ‘singing’ to the girls or ‘calling them’. It is certainly announcing his presence, but it is just as much a declaration marking territory as anything else.
When a confrontation does happen, it often does not result in the two koalas physically fighting as such. There is a lot of posturing, noise and displays of really interesting behaviours. These interactions can occur between any two males. They could both be juveniles and quite inexperienced. One might be a juvenile and the other a low-ranking male. The behaviours still look much the same regardless. If habitat is under a lot of pressure, there could be more of this behaviour due to those stressors.
The Alpha Look
We can usually pick an alpha male koala by sight quite easily as they do have a distinctive ‘big fella’ look.
The first thing we usually notice is they have large heads and thick strong necks that connect to a strong chest. This chest sports a large, frequently rubbed scent gland. The scent gland looks particularly large because it exudes an oily substance. As they constantly rub this on the tree trunk it stimulates the gland and spreads the oil through their white fur.
The alpha is normally larger than the other males in the colony, although size alone does not define alpha a male as an alpha. In Northern New South Wales, where Koala Gardens is situated, we expect alpha males to weigh 8-10 kg. Other adult males in the colony are more likely to weigh anything from 6-8.5 kg.
Along with this weight is a general ‘feeling’ of being ‘bigger’ or more masculine looking. It is hard to describe until you have had close contact with lots of koalas. However, you develop an eye for this and find you can look at a certain koala and just say – oh that’s an alpha.
Many males are a similar size to large females and may not have such a distinctly different look to them as the alpha does.
Why do alpha males ‘look’ different to low ranking males?
The main difference in the ‘look’ of the alpha male is their size, scent gland and masculine appearance. This can often be a ‘rugged’ look too.The reason these alphas are bigger comes from a number of factors.
The alpha will be more active, moving more frequently and over larger areas from juvenile age and will therefore need to eat more. This means they tend to develop more muscle. It is more complex than this however as from puberty they have higher testosterone and cortisol levels. Particularly during the breeding season.
It becomes something of a cycle. Each year they move in larger areas, work harder by moving more often patrolling and engaging in behaviours with other males.
Their scent gland is more pronounced and active. They exacerbate this by rubbing it more frequently than lower ranking males, on more trees. This rubbing continues to stimulate the gland. This stimulation makes it more obvious as hair in the centre of the gland is rubbed away.
As they progress through adult life they end up in altercations with other males. But, also with females when attempting to mate. This results in lots of wounds to the ears, nose and face. These wounds can give them an appearance of being aggressive which can be quite deceiving.
Is it more difficult for the other males to mate if they are not the alpha?
Will the female only be attracted to the biggest, strongest, most aggressive alpha rather than other males? We might presume females are going to be more likely to mate with the alpha. This is often true, but that doesn’t mean he is the only one that gets to mate and pass his genes along.
Females are very picky about who they will mate with. This means there is a lot of loud posturing, attempts to grab and mate her, screaming and bellowing. The female will often still show all this behaviour even with the male she chooses as she will ‘test’ him.
Females making breeding choices
Some koala behaviour observers believe the female chooses different males each year. We don’t have enough evidence through DNA studies to be sure this is the case.
However, observations suggest koalas have an inbuilt need to ensure genetic diversity. For this reason it would not be surprising if a female will produce offspring from a range of males during a full, healthy lifetime.
A female may also be mated by more than one male before a pregnancy results. Males are opportunists and the desire to pass on genetics is strong. A female may choose a male for reasons other than he is the biggest and has the strongest scent gland smell.
So, it may be more difficult to achieve success in mating if you are a small male. With all the posturing and fighting behaviour that is part of the mating ritual for koalas, it is less likely that a 6 kg male will subdue and mate with a female that is larger than him. He may be successful however with a younger inexperienced 4 -5 kg female.
A larger male that is not alpha, may or may not have reasonable success mating. It is going to depend on just how many other available males are around as this will influence how likely he is to even get the chance to attempt.
Are there alpha females?
Often, a particular female in the colony will take on a role where she seems to keep an eye on other younger females, particularly her daughters. The role is not one that is as defined as the alpha male who is very territorial. However, it is recognised by a lot of behavioural observers that I talk to.
Mist was an alpha female. There were times in the early years that I observed her in trees with other younger females with joeys. However, I can’t completely state that this because she was providing support. Possibly, it was because there were only a few dozen large trees here then. Now there are around 4000 trees of various sizes. This may be an influence and is one of the ways I can happily state that there is still always so much to learn about koalas!
Is there such a thing as a beta male and can he become an alpha to take place if the alpha dies?
There is no documented evidence of studies that show anything like a beta male. However, there a distinct hierarchy underneath the alpha. But, not in such a way as one is designated to take the place of the alpha – a passing of the leadership.
Within his home range, there will be other males whose home range overlaps this area. These males know each other by smell and sound. They may, at times, even use some of the same trees. Obviously, not at the same time unless there is an altercation of some kind happening between them.
Habitat counts
Depending on the quality of the habitat, there may be one or several other adult males with overlapping ranges. Some of them might be quite large and move over large areas. They do not communicate in a way that denotes any kind of structure that you would see in a community of animals that socialise together. They communicate purely through leaving scent messages throughout the trees and bellowing from specific locations.
There may also be one or several young males from 1 – 3 years old within that range. Again, it will depend on how much habitat there is available for feeding from. This number will change each year’ particularly during dispersal season. The number will also go up and down in response to climate factors, pressure from high birth numbers or habitat destruction in surrounding areas.
There is no clear beta male that will ‘take over’ because an alpha dies. The most likely thing could be that a young male around 3 years old might take over as alpha during the 12 months following the death of an existing alpha. Had that alpha stayed, this younger male would have dispersed out of the area. That young male would not have stayed in the colony to be a second in charge.
Hierarchy of males in the colony
The most likely classification for such a male is as an immature alpha that was not ready to contest territory. Because of this, he received the opportunity to stay. This is in opposition to a beta male who is second in charge until the loss of the alpha.
However, if the alpha is lost, and no alpha moves in for some time, a lower ranking male may be the ‘most dominant’ male in the area. This may give him more mating opportunities, and he may move through a larger area than he was.
If a true alpha male disperses into that area after some time he may simply return to his lower rank without much true contesting as he was simply being an opportunist.
Having a strong alpha male in residence will support a colony that is healthy and stable.
The sudden loss of an alpha male can spiral a colony into collapse with members dispersing and take years to build back up with a new alpha.
It’s all about the trees!
Providing abundant diverse habitat with strong connectivity is critical to maintaining thriving koala colonies. Young koalas need to safely disperse and have opportunities to settle where there is food and other koalas. Alpha males will be stronger and maintain their home ranges for longer. This provides stable colony environments to all the koalas that live in his range.
The more often the alpha male changes in an area, the more often the colony structure is disrupted. This causes an effect like throwing a stone in a pond and watching the ripples spread outwards.
If one alpha loses the contesting of his range and a new alpha moves in, the new alpha may contest other alphas nearby, hoping to control a larger area.
Or the new alpha may be young and inexperienced and only move about in a much smaller home range. He will encounter the other lower ranking males and have to establish hierarchy matters with them.
Katrina says “As humans, we don’t normally see much of the intricacies of this happening. I know that over the years when an alpha changes, there can be many ripple changes among all the colony members. Some will simply disappear quite quickly, and I can only presume they change their home range. I don’t normally get to know whether they move only a small distance. Maybe the impact is greater and they find themselves having to search for a new place to settle.”
Abundant, diverse habitat
We know that when there is abundant diverse habitat, colonies experience less stress and stability and health levels are increased. It can be stated as a general term that colony members will generally live longer on average. They will also be more likely to remain in their home range or very close surrounding areas for life.
Life can be reduced to an equation of calories in – calories out on a daily basis. Abundant habitat with a stable community structure means many benefits. These include reduced calories spent searching for food, fighting, crossing roads and encountering dangerous human situations. They can literally spend the calories they take in on living and breeding.
In Summary
Koalas are solitary animals that live in colonies that do have a definite structure. The structure is changing each year as young are born, maturing, aging and dispersing in or out of a colony area.
A colony is defined as the koalas living in the home range of an alpha male koala.
Alpha males look bigger, heavier and more ‘masculine’ than other males and have a large, well-used scent gland. Rather than aggressive, they are calm and confident but will defend their territory.
The alpha probably gets to breed more over his life span than lower ranking males, but all males will take opportunities to pass their genetics on. It’s important for genetic diversity that the other males do get some opportunities to breed.
Alpha males live a tough life. They may concede their home range to another younger alpha as they age if it is contested and the younger male wins. All males will engage in fighting behaviour throughout their lives to keep the colony social structure stable.
While an alpha male’s perfect world would see him settle in a home range and rule over it for his entire life, the real world is more complicated. With dwindling habitat they find it more difficult to locate a suitable area to easily settle. Injuries and disease may shorten the time an alpha remains in the top position in his home range.
Some alpha males don’t establish a home range for years and may live a nomadic life wandering and taking opportunities as they can to breed.
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