A lot of folks have inquired lately about what’s going on
over here, perhaps because there have been so few contributions to this blog
lately. In fact, we’ve been extremely busy doing loads of different things
here, but this week in particular has been exciting because we’ve been doing
pilot experiments looking at hyena responses to life-sized stuffed lions. The
stuffed lions are on loan to us from Craig Packer’s lab; one of his graduate
students working on inter-specific relationships among large carnivores, Ali
Swanson, brought them up to us from Serengeti a few days ago. These lions had
been used several years ago when Packer and colleagues were inquiring why lions
have manes, but encounters between the fake and real lions in those experiments
caused the stuffed lions to suffer some wounds. Therefore, upon Ali’s arrival
at fisicamp, our first task was to repair some of the damage inflicted on the
stuffed lions by their real counterparts. Although Ali and I initiated the
repair work, both Josephs and the other guys who work in our camp soon took
over patching various holes in the stuffed lions. Stephanie Dloniak flew down to
the Mara with her sound equipment so we could call hyenas in to interact with
the stuffed lions.
My goals in asking Craig & Ali if we might borrow the
stuffed lions was to run some pilot experiments inquiring about the
circumstances under which hyenas help one another. One of the most common forms
of cooperative behavior among hyenas is the formation of coalitionary mobs to
drive lions away from their kills or from
the hyenas’ own dens. With the life-size models, I hoped to vary odds
ratios (numbers of hyenas relative to numbers of fake lions present) and
pay-off schedules (the quantity of meat available for the hyenas to steal from
the fake lions) to inquire how these variables affected the hyenas’ tendencies
to call in allies and cooperate with one another. Going into this, we had no
idea whether the hyenas would even behave towards the fake lions as though they
were real, but they most certainly DID for a surprisingly long time!
It rained hard the night Ali and Steph arrived in camp, so
the next morning we ran an initial pilot experiment with the Talek East clan,
whose home range includes our camp, so we didn’t need to drive far in the mud
to set it up. We made both models into females by removing the mane from one
model, placed the stuffed lions on the side of a hill, and dumped a few chunks
of meat in front of the models. Then Steph played loud sounds for several
minutes of lions and hyenas interacting over a kill through a speaker mounted
on the roof of one car (the sound tape was made in Botswana by former
fisicamper Anne Engh; thanks Anne!). We had observers and videographers in each of three vehicles
positioned at 12, 9 and 3 o’clock, such that they would be able to capture
events and hyena IDs from multiple angles. We performed this experiment at the
edge of the Talk East home range, so the call-in tape only attracted 5 hyenas,
but they appeared to be fooled by the fake lions, as they were clearly very
nervous. Some of the observers were situated on car roofs or standing to film
out of open roof hatches in our vehicles, and the hyenas in this clan are very
shy, so they all ended up running away after several minutes rather than attempting
to get the meat chunks. We failed to attract any adult females to that scene
(only adult males and subadults), which might explain why none of the arriving
hyenas vocalized to call in allies. But we learned valuable lessons from that
little experiment nonetheless including how our vehicles needed to be
positioned relative to the fake lions, and that we all needed to remain
strictly inside our cars.
Yesterday morning we ran the experiment on No-Name Hill,
which is in the center of the Talek West territory, not far from the communal
den. This time, we kept all the vehicles fanned out at much tighter angles to
one another so the hyenas had more unobstructed space in which to move around
the fake lions, and all observers and videographers remained inside their cars.
We also made one of the two lions into a male by replacing its mane with velcro,
positioned the fake lions at the edge of a small clump of bushes, and increased
the number of meat chunks placed under the chins of the fake lions. Once again,
Steph played the call-in tape for a few minutes, and almost instantly hyenas
started appearing in the tall grass of the surrounding plains.
The first hyena to arrive on the scene was an adult female
who ran around whooping madly while also pooping in apparent fear of the fake
lions. Shortly thereafter more hyenas arrived, and soon we had nearly thirty
clan-members loping excitedly around the fake lions, and vocalizing. We heard
alarm rumbles, and various hyenas whooped and greeted at the scene, so they
were clearly “talking” to one another. Soon we had nearly 30 hyenas there. Most
hyenas kept a respectful distance from the lions, but they were clearly all
scenting the meat. Some hyenas would periodically start to move in closer to
the models but then one would scare itself, and everyone would dash away again.
You can see the hyenas’ fearful behavior in many of the great photos Steph took
(a few shown here).
I found it very interesting to watch individual variation in
boldness toward the models, indicated by how close the hyenas were willing to
approach them. Some approached to
only a single body length away whereas others stayed 100 body lengths from the
lion models. Eventually, when the models did nothing for quite a long time,
some of the boldest females, including Loki, Parcheesi and Monopoly, darted in
and grabbed chunks of meat from under the lions’ noses. They were then chased
all over the place by higher-ranking hyenas until they eventually dropped their
chunks. Even after all the meat chunks had been taken, lots of hyenas were
still milling about, so we had to pull our cars forward and block the hyenas’
view while we loaded the fake lions back into our pick-up and covered them up.
Disappointingly, we did not see even a single coalition form
during the entire experiment. This may be because the lions never did anything
to keep the hyenas from eventually coming close enough to grab the meat. We were
hoping to try another experiment this morning with the Fig Tree Clan, but there happened to be real lions prowling about at the call-in site
when we arrived, so we will try that again tomorrow if the actual lions are
gone. This time we hope to use hidden speakers to periodically play lion sounds
from under the models to determine whether this might affect the hyenas’
tendencies to cooperate. But even if they still fail to cooperate, these lion
models could clearly still be very useful in analyses of boldness and
communication among the hyenas. And as everyone present will tell you, these experiments are a LOT of fun!
Thanks again to Steph Dloniak for taking all these wonderful photos!
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