Are you confused about how koalas live together, while not living together? Let’s see if we can unravel some fascinating koala behaviour together.
Koalas are solitary animals. They will seek out a mate, but do not socialise the way social animals do. We do see mums and joeys together during the first year. However, once weaned they soon separate for life. Each koala, whether an alpha male, a breeding female, a lower ranked male or a juvenile, have their own home range within a colony. These home ranges will overlap each other.
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.
Alpha male koalas are definitely bigger and stronger than the other males around them. They often have a large round face and a strong thick neck which makes them look bigger, heavier and more ‘masculine’ than other males. They are not however aggressive, but calm and confident. They will, nevertheless, use their strength to defend their territory in every way if challenged. This includes fighting, but this is never the first choice for any wild animal. Any injury can compromise their ability to survive. It is possible during fighting for a koala driven to an outer, thin branch, to fall from the tree in these circumstances.
Clinger was the colony alpha male at Koala Gardens in 2014, when Katrina started to record koalas on the property. You can read about Clinger and his life at Koala gardens here
‘Alpha male’ is actually what we would call a character trait in humans. Some male koalas will never develop “alpha” characteristics 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’. However, the absence of an alpha may improve the mating opportunities for a lower ranked male.
An alpha has a large, well-developed scent gland. He uses this to mark his territory and to attract females. In a mature alpha the scent gland looks particularly large because it excretes an oily substance. As it is constantly rubbed on tree trunks, it stimulates the gland more and spreads the oil through their white fur. This leaves a brown ”stain” surrounding the gland clearly visible of the male’s chest making it seem even larger. The gland itself becomes more obvious as the hair in the centre of the gland is often rubbed away. An alpha will also have a strong, deep bellow which he uses to announce his presence in his home range to other males and, of course, to females.
Jordan was a colony alpha male between 2015 and 2020. His very dark fur is a a feature of many koalas from the Tuckurimba area. You can read about Jordan’s life at Koala Gardens here
As a solitary, territorial, animal, an alpha male koala does not “rule over” other males in the way an alpha male of highly social species, for example the leader of a troupe of primates, would. For the most part, an alpha’s “battle scars” are more likely to have been caused by females during an attempt to mate, rather than from a fight between males. The scars are not an indication that the alpha is meaner or more aggressive than other males.
Alpha males may have huge variations in the size of their home range because this depends on a number of factors. The main factor is how much food is available in the area and how many koalas are competing for that food. Some alpha males may have a range as small as one or two hectares. Another could be traveling over an area of 40 km or more, especially where food resources are very sparse.
As an alpha needs to scent mark throughout his home range, he must move around his territory on a daily basis. It is rare to see an alpha in the same tree for several days in a row unless there is a female he is intent on mating. An alpha may sleep a little less than other males and eat more.
Zorro was a colony male between 2015 and 2017. Zorro is a character in “Finding Koala Gardens” and “Fire” – the first two books in the “Adventures of Mist” series of books aimed at encouraging children to engage with nature. You can read about Zorro’s life at Koala Gardens here
An alpha that has established his territory will stay there for the bulk of his life. 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.
The colony 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 to the health and genetic diversity of the colony that the other males do get some opportunities to breed.
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 and testosterone levels are rising. Younger males begin to move through the landscape dispersing. They will take any mating opportunities as they can in the process.
This means, an older alpha male, is going to encounter younger males that are keen to have an opportunity to mate. He may be defeated by a younger male who takes over all or part of his range. Depending on individual circumstances, one alpha male may live a longer life with a large home range and strong colony. Another may take on a less optimal area or suffer some injuries and hold a dominant position for a considerably shorter time.
Hugo was colony alpha male between 2019 and 2022. Having the large round head and strong neck which are often features of an alpha male, he was nicknamed affectionally “basketball” by his many fans. You can read more about his like at Koala gardens here.
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. This may see members dispersing in all directions. It can take years to build back up to stability with a new alpha.
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. Alpha males live a tough life, and 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 posturing behaviour and ultimately fighting throughout their lives to keep the colony social structure stable.
Valentine, named after the heart shaped pigmentation on his nose, arrived at Koala gardens in late 2022 as a young adult. Despite spending time off the property being treated for chlamydia at Friends of the Koala (hence the red tag which can be seen in his left ear), 2023 saw him established as the colony alpha male. His journey at Koala Gardens continues, but his story to date can be found here
For koalas to thrive they need mature habitat with good connectivity. We know that when there is abundant diverse habitat, colonies experience less stress and stability and health levels are increased. With a biodiverse habitat, including mature trees, colony members are more likely to remain stable in their home range for life.
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 and remain. Injuries and disease may shorten the time an alpha remains in the top position in his home range.
Did you find this fascinating? You can watch Katrina giving a deep-dive explanation of alpha male koalas:
In the end the need for good mature habitat is paramount – for all koalas it really is “No tree, no me”
Join the Colony and get involved
You can become part of the Koala Gardens Colony by adopting one of the resident wild koalas. You can also become a Patron, and one level has an adoption option.
Come and discuss Koala Gardens and all things koala on Discord where we hold lots of interesting and often in-depth discussions there. Lots of fun!
You will become part of the family and help provide much needed koala habitat.
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Koala Gardens publishes a small number of delightful illustrated children’s books in the The Adventures of Mist series. Check out the beautifully engaging and educational design. Our mission is to help children to “Fall in love with Nature”.
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