The Kangaroo Hop – Part 4: Agility

Kangaroos have an amazing ability to turn quickly!  They can achieve a 180 degree turn in a single hop, like this girl with baby on board, is doing here:

Their agility is partly due to their shape.  Basically, they have big, strong hips!   Their upper body, in contrast, is quite slim, light and flexible.  They can twist from side to side, crouch, then straighten all without moving their back legs at all.

 

This arrangement makes a lot of sense.  Unlike most grazing animals, kangaroos don’t need a long neck to reach the grass.  We don’t know this for sure, but that could be advantageous: short neck = short distance from mouth to stomach = fewer muscles required to move food = less energy used.

Hopping as a means of locomotion probably also gives kangaroos an ability to turn “on a pinhead” which would be very useful for escaping predators.   We don’t know of any terrestrial mammal that can turn as sharply as a macropod.  With the centre of gravity at the pelvis, the kangaroo is a pivot that can almost turn on a point.  Most land-based mammals have a long body, with their weight centred between the front and back legs.  The length of the body limits the turning circle.  In a way, they have to wait for their back legs to catch up.   Also, the speed limits the turn – the faster they go, the harder it is for them to turn, and the more stress it puts on their legs, ankles and feet.   We suggest that even at speed a kangaroo could turn very sharply without damaging their legs because most of the turn is executed while airborne.

Check out these two pictures.  I found this big male sleeping in the sun.  We saw each other suddenly, when I was only metres away from him.  He quickly scrambled upright, but was facing me:

then he was off, bounding away from me  a moment later:

Note how his back legs are at different positions here.  The leg closest to us is has come further off the ground as the turn is executed.  Just after this, while airborne, the legs re-aligned so that the next time he touched the ground both legs were in sync.

Interesting, hey?

References:  Fauna of Australia: 29. Macropodidae, I.D. HUME, P.J. JARMAN, MARILYN B. RENFREE & PETER D. TEMPLE-SMITH

The kangaroo hop – how does it work?

by Janine Duffy

The kangaroo hop! The most distinctive thing about kangaroos & wallabies. How does it work?

Part 1: the tail.

A kangaroo’s large, heavy tail moves up and down in time with the legs – can you see in this picture the different positions of the tail? The pumping motion of the tail helps oxygen move in and out of the lungs. The tail also acts as a counterbalance, keeping the animal stable.

It is possible for a kangaroo to hop without a tail, but they probably tire more easily.

The kangaroo hop, part 2: The legs.

A kangaroo’s large back legs are very powerful and can propel them up to speeds of 64km/hour (40 miles/hr). As the legs bounce with each hop, energy is stored in the tendons making the next hop easier – so, once they’ve got started it’s easy for a kangaroo to keep hopping. At cruising speeds they use less energy than a four-legged animal running at the same speed.

Interesting diagram at this link:  http://people.stfx.ca/bmarshal/201/kangarookinematics.html

The back legs of a kangaroo have huge areas of muscle, and very large, long tendons. The Achilles tendon on a medium-sized kangaroo is 1.5cm diameter and 35 cm long. Human achilles tendons are about 15cm long.

To increase speed a kangaroo increases stride length, so they don’t bounce more often, they just cover more ground with each hop. We’ve seen footprints 9metres apart – that animal would have been moving quite fast. Over 35km/hr they do increase both stride length and hopping frequency, which does use more energy, so they only do that in emergencies.

The Kangaroo Hop, part 3: The feet.

Kangaroos have very long feet – almost as long as their shins/lower legs. In fact their scientific name: Macropus means big foot. The length of the foot increases the length of their legs, and provides great leverage.

When hopping, only the lower part of the foot touches the ground – see picture. So a kangaroo is effectively running on the tips of their toes. You can see this in their footprints – click this link to see a photo: kangaroo footprints
We can’t find any scientific research to support this, but we think kangaroos move extremely quietly compared to other animals. Maybe because they are in contact with the ground so little, or because their feet are soft (like a dog or cat’s), or maybe because they have only two feet to worry about they can place their feet carefully. Whatever the reason, a large mob of kangaroos can hop very quickly without much sound at all, even through Bush full of sticks and dry leaves.

The stride length of a kangaroo hopping at speed is long – 6 metres at 50km/hr.  That means they are only touching the ground 2 times a second.  In contrast, a galloping horse touches the ground four times in each stride, and has a foot in contact with the ground at all times creating a constant drumming sound.  At the same speed a horse touches the ground 8 times a second.

The best way to understand the kangaroo hop is to watch it in action.  Come to Melbourne, Australia and take the Great Ocean Road 3 day tour or Koalas & Kangaroos IN THE WILD day tour. You’ll learn all about kangaroos and koalas as well!

Kangaroos also have great agility due to their hopping style – read more here: Kangaroo Agility

 

 

Wild koala happenings over the last 15 years!

Few people look up noses for a living.  We do, and we’re proud of it!  Luckily, koala’s noses are much nicer to look at than some noses…

wild male “Bear”

In the spring of 1998 I was walking along a gully looking for wild koalas for a group that were on their way to see them.  I had located a male, who I’d seen several times before.  At least, I think I’d seen him before – I really couldn’t be 100% sure.  He looked about the same size, was in roughly the same area.  But how to tell a big male koala from another big male koala?  They all look the same really.  Or do they?

So I studied this guy – grey fur, white belly, a bit brownish on the back – like every other koala I’d seen.  Not much help.  Look at the face, I thought.  Then suddenly I saw it.  White in the black nostrils.  Different pattern in each nostril.  Bingo.

Since then, we haven’t looked back.  Turns out, we discovered a new method of identifying wild koalas.  It has never failed us through whole lifetimes of koalas. Using it we set up our Koala Research Project.

wild female Ingrid, a survivor

Scruffy, Russell Crowe, Ingrid, Poppy, Daisy and her sons Lacka and Rudi, Bear, Clarence, Santa Barbara, Jamie and Garry Plant became part of our world.  We learned so much from them.  Then, after 7 happy years watching koalas in the Brisbane Ranges National Park, everything changed.  A bushfire ripped through our koala area, killing 90% of them.  Jamie, Bear and Ingrid were the only survivors.

Bear, back home

We had to find another area to visit for our tours, but we continued to monitor the Brisbane Ranges koalas for a year after the fire.  Ingrid and Jamie lived full, long lives in their original home areas, even though it was burnt badly.  Bear spent 3 weeks in hospital while his burnt feet healed, and was released back home, healthy and well.  After about 6 months he left and presumably found a new home.  He gave us an experience we had never dreamed of – close interaction with a wild koala during the capture and rehabilitation process.  He demonstrated to all that he knew us, partly by giving me a “koala kiss” on our first meeting after the traumatic capture.  He then gave us the best experience of all: to release a healthy wild koala back to their home.

the matriarch: Smoky

Our new koala research area was in the You Yangs Park, about 20 minutes away from the Brisbane Ranges.  We found a thriving koala community there!  There was the royal line: Smoky and her daughter Pat, and grandsons Pitta, Clancy and Banjo.  There were the lovers: Karen and Merle; the battles: Vegemite vanquished Tim Tam, and then Anzac beat Vegemite; the movers: Vegemite, Vincent and Clancy, who all moved east to our new research area, and Nova, who moved west.

The Princess: Pat, with second son Clancy

There has been drought, fire and flooding.  But through it all, our knowledge of wild koalas has grown, and our relationship with them has become stronger.  With the help of our guests, we are now creating koala habitat in the You Yangs so that more wild koalas can live in safety.

We hope we have lots more to report in coming years!

wild male Buck

To those we have loved and lost, we thank you.  Here they are:

BRISBANE RANGES:

Scruffy, Russell Crowe, Tess, Placid, Fran, Poppy, Garry Plant, Santa Barbara, Clarence, Maria, Constantine, Ingrid, Canada, Georgia and Calusa.  Note: we don’t know if Ignatius, Rudi and Lacka were in the fire zone.  We hope they survived.  Daisy was found, alive and well, a few years ago with a baby!

YOU YANGS:

Grace, Boof, Calvin, Raini, Coal, Tim Tam, Xavier, Eureka, Emily, Mary, Svea, Karen, Zelda, Ngallo, Barak,  Billibellary, Buck, Neerer, Oatsie, Vegemite and just recently, Smoky.

To those still making our lives richer today:

Aki, Aris, Anzac, Arne, Bandit, Berrijin, Benbo, Bundjalung, Bungaleenee, Clancy, Cloud, Carninje, Corrin, Cruiz, Darren, Derrimut, Elizabeth, Emma, Fairy, Kenny,  Jin Jin, Mear, Moijerre, Marpeang, Nova, Pat, Truganina, Vincent, Wathaurong, Worinyaloke, Winberry,

and to those who’ve gone AWOL, may you be well:

Barere, Felicia, Leah, Kulpendurra, Nina,  Pitta, Banjo, Sophie, Geisha, Keyeet, Parley, Tollora, Wenn, Casa, Kolain, Murrumbean and Wonga.