Silverback gorilla papa Kwan, 23, is pretty "hands-off" when it
comes to his two new babies, Patty and Nayembi, born in the fall
just under one month apart.
Kwan keeps a protective eye over the two different moms and the
babies. But, for the most part, he "just kicks back and lets the
ladies do the work," said
Lincoln Park Zoo spokeswoman Tiffany Ruddle. "If there's too
much play around mom or baby he'll step in."
With so much responsibility falling to the two mothers,
17-year-old Bana and 16-year-old Rollie, the Lincoln Park Zoo
staffers made sure their gorillas were prepared to handle their
demanding parental duties by providing maternal training before the
babies were born.
During maternal training, Bana and Rollie learned to present
different parts of their bodies, including their breasts and
genitals, to be inspected by staffers. The expectant
moms were taught correct baby positioning, so that the
babies would go into the correct nursing positions. And they
learned to retrieve their babies, so that if the babies are resting
somewhere unsuitable the moms can be signaled to go retrieve
"Most of these behaviors are behaviors that you have to shape.
It's not like they know 'mammary' or 'breast' that they're going to
present it immediately," said
Michael Brown-Palsgrove, zoological manager of
the primate department.
To shape a chest presentation, for example, the
trainers would use a "target stick," said Palsgrove, who added
that they primarily did this to test for milk production. If the
baby wasn't getting enough nutrition, for example, the
trainers would want to see if the mother was producing enough
milk, and to do that they would have to manipulate her chest.
The trainer is always in protected contact, Palsgrove said,
so there's always a mesh barrier between the gorilla and the
"You would stick a target stick through the mesh and say
'chest,'" Palsgrove said, "and then the gorilla would
be reinforced for 'testing' their chest. Then you
would hold the stick away from the chest and say 'chest' and
if they move their chest to touch the stick then they
would be reinforced."
Eventually, said Palsgrove, staffers would just move the
gorillas closer and closer to the mesh until the
chest was pressed up against the mesh. And then they
would know that was the behavior we wanted. that their chest should
be touching the mesh. And then we would start
desensitizing them to us touching it and then
When they go through the process they aren't yet producing
milk. "We just wanted it in our back pocket in case we
needed it," said Palsgrove.
All of the training is optional. The staffers ask
for a behavior and the gorilla can choose to do it or
not to do it. If they do it though, they get
reinforced with food.
"They can decline and not participate, but then they would
not get the positive thing which is the food
reinforcement, said Palsgrove.
All of the animals learn differently, so they utilize
different tools to get desired behaviors.
Rollie tends to be quicker, because she has been involved in
the training process longer than Bana, said Palsgrove.
But, generally, the staff agreed that Rollie learns
things much quicker than Bana.
"Bana is very deliberate with her actions and that's the way
she is with her baby as well. She is very deliberate
with holding the baby and supporting the baby.
Rollie's a little more laid back and quick with her
This is apparent in their parenting styles: "Bana, the
mother of the older gorilla baby, Patty, is really
protective," said Ruddle. "Rollie is a great mom, but
a little less 'helicopter parentee,' so she might like let her
ride on her head, which she likes to do, which I think
is awesome. Or you know, let her ride on the belly or
even set her down while she makes her nest. I mean,
keep an eye on her but not so on top of her."
Palsgrove and Ruddle said that, so far, Rollie and Bana are
taking excellent care of their babies and that they
haven't had to employ any of the maternal training,
but it's always good to have it in place.
Right now the mothers are starting to allow the infants more
independence. So you'll see them sometimes sitting
away from the mother. They are starting to figure out
and explore their environment.
"The mothers are always right there but we're seeing great
milestones," said Ruddle.
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