July–August 2015 25ADELAIDE ZOO/ DAVE MATTNER/KATE FIELDER/NATHAN LANGLEY
O
NE DAY in November last year,
zookeepers at Adelaide Zoo
awoke to a horrible surprise. A
branch in an enclosure had fallen during
the night killing Kiunga, one of their
pair of endangered Goodfellow’s tree
kangaroos. Even worse, she was a three-
year-old female, thought to have a tiny
joey in her pouch.
But all was not lost. For several
decades Zoos South Australia, which
includes Adelaide Zoo, has pioneered a
clever conservation breeding method
called cross-fostering (see AG 98).
They’ve successfully increased
populations of southern brush-tailed
rock-wallabies and mainland tammar
wallabies by using less endangered close
relatives, such as yellow-footed
rock-wallabies, as foster mothers. It
meant there was a glimmer of hope.
“As soon as I was called to the
exhibit, I checked her pouch and saw
that there was a live joey,” says Gayl
Males, the zoo’s team leader for native
mammals. “We’ve been doing this for a
number of years, cross-fostering the
endangered Victorian brush-tailed
rock-wallaby into our yellow-foots here.
It’s a process we have used a lot to save
endangered species, but we’d never tried
it on tree kangaroos. It was just a matter
of ‘Hey, we have to try this’.” Without
help, this little joey was going to die
anyway, so there was nothing to lose by
trying the cross-fostering technique.
The procedure for endangered
rock-wallabies works like this. Firstly, a
female needs to be pregnant at the same
time as a female of a closely related
non-endangered species. At an early
stage, the tiny pouch young of the
threatened species is carefully attached
to the teat in the pouch of the other
mother – a delicate and difficult trans-
fer that’s critical to the success of the
procedure. The foster mother’s original
joey is then humanely euthanised. The
endangered joey is brought to a viablestage by its foster mother. And the adult
female of the endangered species is free
to become pregnant again almost
immediately, because kangaroos and
wallabies naturally have another embryo
‘on pause’, ready and waiting to go.
“We know if we remove a joey from a
pouch, pretty much bang on 30 days later
they will give birth to another embryo,
and that’s a really predictable time frame
we can work towards,” says Adelaide Zoo
veterinarian Dr David McLelland. “If
you do that cycle several times you can
increase up to six- or eight-fold the num-
ber of joeys they produce in a year. It’s areally neat way of using their reproduc-
tive biology to our advantage to maxim-
ise the captive-breeding output.”
Using rock-wallaby foster mothers,
the technique had only before been
attempted on closely related species.
And it had never been used for tree
kangaroos using any foster species. Not
only are tree kangaroos distant relatives
of rock-wallabies, they also have many
behavioural and physical differences.
Notably they live in trees and rarely
descend to the ground (see AG 116).
Adelaide Zoo staff had talked
about attempting the technique on tree
kangaroos, but thought they might be
too distantly related for the process to
succeed, Gayl says. “We didn’t expect it
to be successful... We were just hopeful
and then surprised when it passed the
first 24 hours, which is the first critical
period, and then 30 days, which is the
second. It was very exciting.”The zookeepers were expecting the
cross-foster to fail, Gayl adds, because
mother wallabies often instinctively
know when there’s something different
or wrong with joeys and won’t invest
time caring for them. “This joey was
completely different: a different size,
different shape and probably a different
smell,” she says. “Certainly the move-
ment in the pouch was different – this
one just wriggled all the time.”
The initial goal was to get it to the
“eyes-open stage” around the end of
January, when hand-rearing by a human
carer would be possible. Any day after
that would be an added bonus. By 26
February the young joey – which had by
now been named Makaia – was still
hanging on in the pouch, but there was a
danger he’d fall out and be injured. So it
was decided he should be removed, and
Gayl became his carer ‘mum’.
During the day Makaia is looked
after at the zoo and at night goes home
with Gayl, initially needing four-hourly
feeding with formula milk. He’ll con-
tinue to go home with her until he’s
down to three milk feeds a day and will
be weaned at 15–18 months of age.
It’s been hard work, but rewarding.
“He’s cute, very time consuming and a
bit of a terror,” Gayl says. “Because he
can climb, every time you try to walk
somewhere, he runs after you and jumps
up and climbs up your leg. This little
fellow does have a bit of a temper and
has little tantrums, so he’s certainly got
personality... He loves my husband and
snuggles up under his arm and goes to
sleep while he’s sitting watching TV.”
The Adelaide Zoo team will
share their findings with other zoos
around the world that are also breeding
endangered New Guinean tree
kangaroo species, and the technique
may be successfully adapted to help
increase the success of internationally
coordinated captive-breeding programs.
JOHN PICKRELL“It’s a neat way of
using reproductive
biology to our
advantage.”
A tragic accident at Adelaide Zoo has led to a world-first trial of a pioneering
breeding technique for an endangered tree kangaroo species.
captive-breeding success story
Opportunity from adversity
圀漀爀氀搀䴀愀最猀⸀渀攀琀圀漀爀氀搀䴀愀最猀⸀渀攀琀
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