Monday, September 15, 2014

Mama Bear..I mean hyena

            We recently confirmed that Polar, one of our Serena hyenas, has had a cub! As far as we know, this is Polar’s first cub (or at least it’s the first that has survived long enough for us to see it). It is looking very healthy, and Polar is a very attentive mother.

Prepare yourself for adorable photos:

Polar's baby poking its head out of the den

Polar getting her cub out of the den so it can nurse
The first time Molly and I saw Polar’s cub was pretty amusing. We had Polar at the den hole, and a black cub emerged from the den and appeared to be trying to nurse. Polar seemed rather irritated with the cub and would kick it off a nursing position with her hind leg. She finally got so annoyed that she tried to bite it. Molly and I were aghast at Polar’s lack of mothering skills and figured we shouldn’t get too attached to this obviously doomed cub. But lo and behold, a second, smaller black cub popped out of the den hole and started climbing all over Polar. She tolerated this with aplomb, and we later confirmed this was fact Polar’s cub when we saw it nurse. We later realized Polar was sharing her den with another mom, Diggory, and Diggory’s baby had been trying to nurse from Polar. It is not actually uncommon for cubs to try and nurse from the wrong mother, but they are usually quickly told off.

Polar telling Diggory's cub off

Polar putting up with her own pain in the butt cub

Diggory and Polar are keeping their cubs miles away from the communal den, where the older cubs hang out. Moms keep their babies in dens isolated from the rest of the clan while they are still very young. Diggory and Polar are both very protective of this den hole, so woe to any lower ranking hyena who wants to come say hi to the babies. In fact I’ve even seen Diggory chase and snap at Lady, a higher ranking hyena, because he dared to come within 5 meters of her den hole.

Diggory and Polar getting ready to chase off a male who
was silly enough to come within 30 meters of their den.

Polar chasing off some big cubs from the den hole

You might think these ladies are over-reactive bullies who terrorize anyone in the vicinity of the den hole. However, female hyenas have a very good reason to be defensive. Young cubs are easily killed by predators and adult hyenas of either sex.
On the other hand, this still doesn’t explain why Polar was so grumpy when a hungry cub tried to sneak some milk.

Hyena mothers have good reason to try and hoard resources for their own cub. The skull and jaw muscles of a young hyena take a particularly long time to develop compared to other mammals. This is because they need to develop the unique ability to crush bones. During this time of development, which lasts about three years, hyenas can’t eat their normal food very quickly. When you’re competing with clan-mates, which can devour an entire wildebeest in 15 minutes, this could be a serious liability (I grew up in a human family of four, and I’m still not sure how I survived being the slowest eater). Moms play an important role in ensuring their slow-feeding cubs get enough to eat in two ways: 1) Moms aggressively displace other hyenas at carcasses so their precious baby has time to feed. 2) Moms nurse cubs for prolonged periods of time, up to 2 years. Therefore, cubs rely on mom heavily for all their food for a long period of time. So yes, hyena moms have particularly good reason to be grumpy with anyone trying to steal food from their cub.

So good job Polar! Don’t let that bad cub nurse from you!

Polar's baby (left) with Diggory's baby (right)


dee said...

Great post. And the pictures really help tell the story. Thanks. Oh yeah, are hyenas still using the cave as a den?

Hadley said...

Wow, what a perfect way to start a Tuesday, thank you for sharing the story!

EmilyThomas said...

YES! Go Polar! I miss these guy, what is the lineage!?!?!

Lily J-U said...

Polar!!!! Arg so cute hyena cubs... can't stand the cuteness!! Great photos!

Nora said...

Haha love the post and the photos. Nice work, Jones!

Michigan State University | College of Natural Science