Koala love

I’m often asked questions about koala reproduction and considering that we are now entering the peak of the koala breeding season (at Cape Otway at least), I thought I’d put together a summary of what we know about koala ‘love’. Actually, there is not that much ‘love’ involved and for anyone who had witnessed a male koala that is full of testosterone, harassing a female koala that is not interested in him, you’d know what I’m talking about. The female will scream her disinterest and if the male gets too close, she will fight him off with tooth and claw. Eventually, he will retreat, often bellowing (in frustration?). Ten minutes or so later, he will try again. Observations suggest that he will continue to stay close to his chosen female, sitting in a lower fork of the tree and guarding her closely.

A male trying desperately to get some 'love'. He managed to grab the female but eventually
lost his grip and fell about 5m.

 

He  simply climbed back up the tree to await another opportunity

This male took an interest in me. I'd had the misfortune of being urinated on by a female that we were catching. Considering his obvious 'excitement', I think he may have thought I was a female koala.

 

I have only ever seen a few copulations in the wild. In one, the female went to the male (she actually woke him up). In another, the male went straight to the female, passing another female on the same branch. Obviously, given the number of joeys we see, there are a lot of successful copulations. Around 80% of the females in our Cape Otway population this year have joeys. This means that even the food shortage last year did not disrupt the breeding cycle.

The koala gestation period is around 33 to 35 days. The young is born at the embryonic stage (as with all marsupials) and crawls its way to the pouch. Typically there is only one young although twins can occur. In wild populations, it is likely that only one of these will survive through to independence.

Twins for a female at Cape Otway (photo courtesy of DEPI)

The young latches on to one of two teats and will remain in the pouch for about 6 months. The mother prepares her joey for its eucalyptus leaf diet by producing a faecal pap for the joey to feed on. This helps the joey transition from a milk- to a leaf-diet. At 6 to 7 months of age, the joey (300 – 500g) emerges from the pouch and clings tightly to the mother. It will begin eating leaves although continues to poke its head back into the pouch for milk.

After leaving the mother's pouch, a joey will regularly poke its head back in the pouch for a drink.

 

The mother will carry the joey on its back for around 3 months.

 

By 9 months, the joey will weigh around 1kg, and at 12 months and ~2.5kg it is fully weaned. Weaning usually occurs when the mother becomes pregnant again. The mother will become quite aggressive towards her young. This can be heartbreaking to watch – the mother screaming and lashing out at her young, and the young crying. It is not uncommon to see a few of these rejected young hanging out together. On one of my Earthwatch trips, a recently weaned joey even sought comfort from one of the Earthwatchers. It literally chased her and began climbing her leg.

This joey is nearing independence.

There are still a lot of questions about how koalas select their mates and how long males will guard females. I am hoping that we will get some answers to these questions this breeding season. We have deployed ‘proximity collars’ on males and females in the same area. When koalas wearing these collars are within a few metres of each other, each collar will record the ID of the other collar, the time, and the duration of interactions.

What's in a name?

Some say that it is not good scientific practice to name your study animals. Obviously I disagree. I think a name is easier to remember than a number and allows us all to engage more with the research. Besides, Jane Goodall named her chimpanzees so why can’t I name my koalas?

Since 2010, about 50 Cape Otway koalas have been named. I have generally allowed those helping me catch to choose a name but ‘try’ to claim the power of veto. I say ‘try’ because sometimes a name is slipped in without me getting a chance to veto, or I am simply out-voted. Here's just a few that had reasons behind their names...

Princess – captured by an Earthwatch team on the day of the royal wedding. I thought ‘Kate’ would be fitting but I was ignored. 'Princess' lived up to her name though. Such a drama queen in a catch!

Lucie – named for my lovely French volunteer. She had the same sweet personality (See the photo at the top of the blog).

Dave – you just have to love a koala called ‘Dave’. Dave is definitely my favourite.

Kevin – the eleventh koala ever collared... "Kevin Eleven"

Bruce – big, grumbly and slow-moving. Bruuuuuuuccce.....

Bruce

Tony Parker – a French basketballer. Apparently this koala moved just like him? Named by a French volunteer.

Erik – after the Viking (Erik the Red) who was shipwrecked at Cape Otway.

Erik

Mac – moved as fast as a Mac truck.

Frankie – named for Frank from Bimbi Park. We messed up on matching personalities here though. Koala 'Frank' was plain nasty and earnt him the nickname 'Cranky Frankie'.

Beast – quite scary and ‘beast’-like and named by a visiting researcher. We estimate him to be about 12 y.o. so he's my oldest boy.

Beast

Scarface – pretty obvious really. In 2010 I came across him. He had a terribly infected face wound (not sure what caused it) and I didn't think he'd live. A year later, I saw him with a healed but scarred face so decided to collar him. He still lives on.... a resilient fellow.

Scarface

Emily, Charly, Georgie, and Benjamin were joeys named for my three nieces and nephew. Some of the few named by me and obviously the cutest joeys ever.

And from our latest trip, we have Diamond named as a thank you to Mitsubishi, Fran named for San Francisco zoo, and Sarah and Tigger both named by Earthwatchers for their own personal reasons. Next week I will be heading back to the Cape to add another 16 koalas to the list. Any suggestions for names?

Cut..... Take 137... Rolling....

I was fortunate to be able to join the September Earthwatch team for a few days of their trip. 'Fortunate' in that I loved spending time with yet another group of enthusiastic people who share my passion for the environment. The unfortunate part was that it was only for a few days AND involved a lot of time spent in front of a camera, often having to repeat the same tasks and conversations multiple times. One of the holes I dug while planting trees nearly took me to China it was so deep by the time the film crew got their perfect shot. I know the promotion of the project will make it all worthwhile though. Mitsubishi has generously provided funding to Earthwatch to make a documentary of the 'Conserving Koala Country' Earthwatch trip.
 
Despite all that was happening, I did get a chance to find our old collared friends. Bella is looking good and appears to have decided to settle in her new area over the hill. Buffy also hasn't moved much since February. Sally is back in her original range and has a tiny pouch young. I only caught a glimpse of a leg poking out of her pouch. No wonder she left Sammy behind in March... she needed to prepare for a new joey. I found Dave sitting in a tree near the driveway of Pat and Cyril's and he bellowed a greeting.

I took the film crew to meet him so that they could film him bellow but Dave turned camera shy and just scowled at us. Interestingly, Scarface was sitting in the neighbouring tree to Dave. I was happy to see him because he dropped his collar months ago so I haven't seen him for a while.

Dave goes camera shy

Scarface still hanging around

True to form, Beast was trying to romance a female. Judging by her screams, she wasn't interested but I'm guessing he will wait until she is. He's pretty persistent. We caught both Beast and the female (now named 'Tigger') and put proximity collars on them. These will tell us when they finally do get together and then when they break up. That's koala love for you... not long term! Each collar has a unique code and when within a few metres of each other, they each record the other code and the time spent near it. Cool stuff!  We also caught and collared a new male named 'Diamond' by Earthwatchers Craig and Robyn. The diamond is part of Mitsubishi's logo so we thought that this name was a nice way to thank Mitsubishi for their sponsorship.

On my last day, we found a female (with a large joey) in the same area as Beast and his as-yet-unwilling girlfriend, so I decided to try to catch her too for fitting a proximity collar. When I finally got myself into a good position to catch (2 anchor points up!), this female decided that she didn't like the idea of being caught and moved just out of reach. Anybody who has ever climbed to catch koalas would understand how I felt at this point. I came pretty close to calling it off... but... it was a perfect koala for the study, the last opportunity to catch on this trip, and ultimately, I am stubborn and hate being out-smarted by a koala. So, I took a deep breath, muttered a few choice words that I hope the film crew didn't hear and record, and anchored a third point in the tree. This time, I managed to get the koala into the neighbouring tree where my able Earthwatchers (Jenna and Tori) could flag her. I was back down the tree in a lot less time than it took me to get up and soon our little mum and joey were snug in holding bags. I am sure that Jenna and Tori were pleased that I didn't call the catch off because they got to mind the little joey (a girl - named Sarah by Jenna) while I processed the mum (named 'Fran' as an acknowledgement for the San Francisco Zoo who sponsored Jenna's trip). Fran and Sarah were soon reunited and released and were climbing their way back up the tree (much quicker than I climbed it!).
 
Today, I am back in Melbourne and feeling a bit creaky, sore and tired. Despite that, I have no regrets. It was such a pleasure to work alongside such amazing people, and as always, a privilege to have the opportunity to study these beautiful animals. I take back what I said yesterday and instead say "I will never be too old to do this".

Thanks to the Earthwatch crew (Kento, Shirley, Robyn, Craig, Jenna, Tori), Alistair (co-PI) and Cass (Earthwatch Australia) for letting me join you, and my Bimbi Park family for everything you do for me (Dimitri - I wish you a speedy recovery). I also would like to thank the film crew (Sharon, Andrew, Brent, Max, Jess, Clint and Amy) for your patience. If there's ever a next time though, makeup, hairstyling, my own motorhome and a massage or two would be appreciated :-) Oh, and I'm going to add a fee for joeys...

Happy days ahead

This field season promises to be an exciting one with the recovery of manna gums in our main site to document, lots of sites to survey for koalas, and some short-term studies of koala breeding behaviour. Our first Earthwatch trip is only a week away with more trips planned for November and February. Earthwatch has arranged for a documentary to be made of our research so the September Earthwatchers can look forward to being film stars!

I last visited Cape Otway two weeks ago and was very happy to see trees continuing to recover. There are fewer koalas than in previous years but this is a good thing because those that are present are healthy. Our collared koalas that survived the population crash are looking good. Buffy has settled in the south of the manna gum site near Bimbi Park, and Beast and Sally are back within their old ranges. Dave has settled a bit further to the north and Bella a few km to the north of him again. Scarface dropped his collar months ago but the locals occasionally see him.

Happy days!



Fewer koalas in Manna Gum means that those that are there are healthy

Recovery...

It is amazing how much comfort can be gained from watching leaves appear on trees.  It happened so quickly (in December) that it almost seemed like it was overnight.  Even the trees that I thought were dead along Manna Gum Drive are now covered in leaves.  Although it is somewhat sad that there are fewer koalas around, there is now hope that some areas of manna gum will survive.  Having that hope has meant the world of difference to the landholders and of course, to me.

Manna Gum Drive, November 2013

Manna Gum Drive, February 2014

In February, I had an absolutely awesome group of Earthwatchers to help me document the recovery: Christine, Alana, Tak Wei, Karina, Pat and Viki (from Earthwatch). With ages ranging from 20 to 70+ and from six different countries, who would have thought that we would have got along so well? There was never (neva) a dull moment.  On behalf of Viki and myself, I even forgive you all for picking on our beautiful Australian accents.  

An awesome group of people!

As is the norm for my trips, we worked hard and surveyed a record 15 sites for koalas and tree condition (including 5 brand new sites), captured our 6 collared koalas, and radiotracked most days.  This is extraordinary in itself, but when you consider we lost a day due to hot weather and high fire danger, all I can say is ‘WOW’!  And we played hard too. Nothing like a competitive game of spoons or the new crowd favourite ‘scum’ that our visiting journo Ken taught us, to top off a hard work day. THANK YOU my friends for helping me recover.

Our 6 collared koalas are still going strong.  All have put on some weight and muscle condition is improving. Sally still had her joey (now named 'Sammy') with her in February but now (March) has left him to fend for himself. She has returned to her old core area several hundred metres to the south and he appeared to be doing OK in the trees she raised him in. 

 

Sally and joey 'Sammy' (Photo by Alana). 
Apparently these are the most beautiful koalas in the world!

The GPS tracks of some of the koalas are really interesting.  Beast, Dave, Buffy and Bella roamed a lot in Dec/Jan. 

Buffy's tracks Dec-Jan

It is intriguing to add the data from the last few months to those of the last few years. The population in our focal 7 hectare manna gum site increased steadily from around 11 koalas per hectare in November 2010 to around 20 per hectare in September 2013. Then the population dropped to 5 koalas per hectare in November. From our radiotracking and GPS data, we know that most koalas moved to neighbouring woodland patches as leaves became scarce in their core areas. This is reflected by the rapid increase in population density in ‘Bush Block’, a few hundred metres to the east, in November. That population also crashed, but this time only the fittest were able to move on.  Only 8 of our 20 collared koalas survived past November.

Koalas per hectare in our focal site (black), and 'Bush Block' (green) since 2010

Tree canopy cover in the focal site reflects the changes in koala densities over the years. As koala densities increased, average canopy cover declined.  A temporary increase in cover due to the summer flush of growth was observed in February most years.  This year the increase has been more dramatic although overall, cover is still lower than that recorded in February 2013. Only time and more data gathering will tell how much these trees can recover.

Average canopy cover (%) in the Bimbi site