Male koalas have a scent gland in the middle of their chest. The gland produces a strong-smelling oily substance that can be rubbed against trees to act as a marker for other koalas.
The scent gland appears to change over the koala’s life, and over the course of a year.
Here are some pictures we’ve collected over many years.
DOMINANT MALE KOALA SCENT GLANDS:
Both of these koalas were dominant males when these pictures were taken. We don’t know if that makes any difference to the condition of their scent gland, but these pictures would certainly show the scent gland of a male in his prime.
Anzac – dominant male for many years. His scent gland shows an interesting central crease in both the pic above in early breeding season, and below in mid breeding season.
The same male in April, after breeding season had ended. His scent gland is appearing more furry and less prominent.
Read more about Koala Anzac here.
The next pictures are of Winberry, who was also a dominant male in another part of the You Yangs for many years. The pic was taken in late September, so technically non-breeding, but very close to breeding season.
Winberry has no central crease in his scent gland.
Winberry again, the year before in April. In both pics the scent gland area appears quite dry.
Interestingly, both examples of dominant males show a dry, clean scent gland – both in and out of breeding season. I can’t find any pictures of dominant males with sticky oily scent glands. Perhaps I’ve missed them, or perhaps they have no need to over-produce discharge?
OTHER MATURE MALE SCENT GLANDS:
Below Benbo, an older mature male in early breeding season showing a slightly oily-looking scent gland.
Below Gurren, middle of breeding season. His scent gland appears very oily sticky. As far as we can tell, Gurren was a sub-dominant male at this time.
SCENT GLANDS THROUGHOUT LIFE:
Koala Clancy is the one male we’ve monitored from pouch emergence to dominant male status.
Clancy below as an 18 month old juvenile. His scent gland is there, but small. The pic was taken in the middle of breeding season, but the season might not make any difference to the scent gland of a juvenile.
Clancy below as a four year old, in non-breeding season. The scent gland is still quite small, but seems to be producing some oily discharge.
Clancy as a 7 year old, in the non-breeding season just before he became dominant male. His scent gland is much larger than in the 4 year old pic above, but furred over and not appearing too oily.
Read more about Koala Clancy here.
It is hard to draw conclusions from the above photographs, except that scent glands in younger males are smaller and seem to grow as they approach maturity. Scent glands do appear dry at times, and oily at other times – but when and why is currently impossible for me to conclude.
Scent glands also appear to have distinctive shapes – Anzac’s was long, thin with a central crease; Winberry’s is more oval; Clancy’s is keyhole-shaped with a bulge below.
Echidna Walkabout’s Wildlife Guides and Koala Researchers find these wild koalas and take photographs and observations of them +/-310 days per year.
The koalas that have been given an age have been monitored since pouch emergence (Clancy) or for many years (Anzac – since 2007 & Winberry – since 2009), which gives us a reliable estimate of their age.
To support our research, please consider joining a 3 day Great Ocean Road, 1 day Sunset Koalas & Kangaroos or 1 day Koalas & Kangaroos IN THE WILD tour next time you are in Melbourne. Over 50% of our profits are invested in this koala research. Learn more about Echidna Walkabout’s Wild Koala Research here.