How male koalas avoid fighting

If you search male koalas fighting you can find several YouTube videos and some sensational articles declaring that koalas fight often. But over 26 years of wild koala research we have only seen male koalas come to blows twice. So are koalas fighters or not?

We believe that male koalas avoid fighting by using a range of vocalisations, postures and behaviours. This finding is similar to that found in wild koala research at St Bees Island by University of Queensland (Ellis, W 2015) that found low rates of male-male interaction.

One of the ways that male koalas may avoid fights is discussed below.

Resident male koalas may give a range of warnings to trespassers to avoid a fight.  In two groups of observations in the You Yangs, Victoria, two different resident males approached closely to a trespasser male for a day, then left the area. We call this a close vicinity warning.  Then 5 days later and one month later respectively, when the trespasser had not left the area, the resident male moved into the tree with the trespasser.  This is a personal-space invasion warning.

One interaction resulted in some blows, but no full-blown koala fight was ever recorded between these males.

movements of 3 male koalas in the You Yangs

Following is an account of what happened and when.

We first met older male Bindjali in late 2015 in an area north west of resident male Clancy’s home range. He was seen only once that year, and three times in 2016 – once in Clancy’s home range, and twice in dominant male Winberry’s territory. He behaved like an old male who had lost his home range to another, and was living on the fringes.

Early in March 2017 Bindjali appeared and stayed in Clancy and Winberry’s home areas, causing some tension.

Bindjali and Clancy

On 11 and 12 March Bindjali was found in Clancy’s home range.

On 13 March Clancy was found 80 metres from Bindjali’s last location.

male koala movements to avoid fighting

We read this as a close vicinity warning by resident male Clancy. As koalas can smell each other very easily, a close approach like this would have been noticed by Bindjali.

The warning seemed to work, because next time Bindjali was found he was 450m away to the east – in Winberry’s home range. He didn’t stay there long – maybe because Winberry was only 250m away – and by 18 March he was back in Clancy’s home range.

But this time there was no close vicinity warning – it was time to step up the threat level. Clancy was found in the same tree as him, giving Bindjali a personal-space invasion warning.

how koalas avoid fights

male koala confident posture

We watched the two males for some time. Clancy was relaxed, resting stretched out, and looking directly at Bindjali frequently. Bindjali was submissive, keeping his body low to the branch, moving slowly and furtively as if trying to avoid attracting attention.

do male koalas fight often

Watch:

The following day, 19 March, Bindjali had moved just 30m to the north and Clancy was nowhere to be found. That struck us as odd – wouldn’t Bindjali try to get as far away as possible? Obviously we don’t know everything that transpires between male koalas.

Then Bindjali disappeared from the area and was not seen again until 1 April, in Winberry’s home range. Clancy was seen on 26 March, back where Bindjali had been, then stayed around the vicinity, as if he was just checking that the trespasser had finally moved on.

We never saw Bindjali in Clancy’s home range again.

Bindjali and Winberry

Bindjali appeared in Winberry’s home range on 1 April. At this time Winberry was 500m away – at the other end of his home range. But it didn’t take him long to figure out what Bindjali was up to.

On 2 April Winberry had moved directly towards Bindjali and was within 280m of him, and when next found on 14 April Winberry was right in his face – only 60m from Bindjali’s location on 9 April.

This was Winberry’s close vicinity warning.

map of male koala interactions movements

Bindjali stayed around that area. He was seen again on 20 April and 23 April in Winberry’s home range.

On 3 May Bindjali was found dangerously far within Winberry’s home range. By then Winberry must have had enough and had to deliver a personal-space invasion warning. On 13 May Winberry and Bindjali were found in the same tree.

male koalas fighting

This encounter was even more tense than the one with Clancy. Wildlife Guide Brett Howell heard Bindjali vocalising from some distance away. Listen:

Brett and his tour group followed the sound and came across Winberry and Bindjali quite close in the same tree. Winberry was higher, Bindjali was hanging on to a thin branch upside down. As they watched, Winberry struck at Bindjali several times with his right hand. Bindjali stayed where he was, yowling and crying.

Watch Winberry deliver his personal-space invasion warning to Bindjali:

male koala during a fight

After this the two male koalas separated – Bindjali moved down lower, unhindered by Winberry. When the observers left they had settled into a position about 2 metres apart. The koala fight seemed to have ended, for the time being.

koala fight ended

We don’t know if we saw the start, the end or just part of the fight. It is noticeable in the video that Winberry doesn’t seem to be really trying to damage Bindjali. Was he mostly sending a message? If the message was not taken, would it have escalated into a serious male koala fight?

On 15 May Bindjali had moved 80m to the north, still in Winberry’s home range, and was found again near there on 17 May. But he has never been seen again.

CONCLUSION:

Fighting between koala males is relatively rare, and little studied. No doubt koalas have found many complex ways to avoid the dangers and potential injury of physical combat. This is just two observed interactions that we found interesting in their similarity. We doubt that this is the sum total of fight avoidance behaviour and much more needs to be learned.

So what’s with all those YouTube videos of male koalas fighting?  Either there’s so many iPhones and video cameras around that even rare behaviour is getting recorded more often, or koalas in populations that are stressed, overabundant or with a shortage of food trees, fight more.  We don’t know how our modification of their environment is affecting their social behaviour.

Do you have a video or experience of male koalas fighting? We’d love to hear about it.

Note on methods:

This data was all collected by non-intrusive observation in the You Yangs by Koala Researchers and Wildlife Guides of Echidna Walkabout Nature Tours and Koala Clancy Foundation. Koalas are identified from a distance by their nose patterns and never touched. All research is paid for by social enterprise Echidna Walkabout, and is undertaken with permission of Parks Victoria.

The You Yangs koala population is located in dry open woodland dominated by River Red Gum and Yellow Gum (respectively Eucalyptus camaldulensis and E. leucoxylon). Total koala population is estimated to be around 105 individuals, and is declining at rates of around 46% every 10 years. The population does not exhibit chlamydia at high rates (only two suspected cases in 12 years), birth rates are around 10-15% per year (we record 4 to 6 joeys per year in our research population of +/-38 individuals) and death rates about 7%. Home ranges are large, (males: 40 to 110 hectares; females 20 to 30 ha) which is not surprising for a dry woodland environment.

Read more about our Wild Koala Research Project here.

LINKS and REFERENCES:

Ellis W, FitzGibbon S, Pye G, Whipple B, Barth B, Johnston S, et al. (2015) The Role of Bioacoustic Signals in Koala Sexual Selection: Insights from Seasonal Patterns of Associations Revealed with GPS-Proximity Units. PLoS ONE 10(7): e0130657. https://doi.org/10.1371/journal.pone.0130657 http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0130657

BBC Earth article: http://www.bbc.com/earth/story/20150711-shouty-koalas-dont-want-to-fight

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