Friday, April 10, 2015

Social rank is incredibly important in the lives of spotted hyenas; high ranking hyenas have better access to food and therefore higher reproductive success than low ranking hyenas. Individuals inherit the rank just below their mother, and when males disperse into a new clan so that they can mate, they automatically fall to the very lowest rank in the clan. Sometimes there are upsets in rankings, but those are generally rare. All in all, individual hyenas don't have a whole lot of control over their place in the social hierarchy. The only hyenas they are allowed to fight with over rank are their siblings.

Hyena cubs are born with a full set of teeth, and are born fighting. There is a great video on Arkive that shows two hyena cubs fighting for dominance shortly after birth, while their mother is still cleaning the placenta off of her third cub. Cubs fight it out for inter-litter dominance in the first one to two days of life, while they are still in the natal den (Smale et al. 1995). Inter-litter dominance can be extremely important later in life. For example, Spencer mentioned in his last post that Pike, our Happy Zebra matriarch, just had new cubs. If both Lance and Morningstar are females, and Pike doesn't have any more daughters, whichever cub is dominant over the other will inherit her matriarch's position. Even being just one position up on the clan hierarchy can make a difference in later reproductive success, and is worth fighting for.

These early fights for dominance are particularly important in litters with three cubs. Typically, litters are only one or two cubs, because hyenas only have two nipples to nurse with. When a triplet litter is born, the lowest ranking of the three usually dies early on, while their dominant siblings monopolize the milk supply.

While it's rare to see three cub litters, I have seen two sets in my time in the Mara. Back in November, in South territory, Heidi and I were enjoying a quiet den session watching Komo's newest cubs, Voyager and Star Gazer romp around. Voyager and Gazer were nursing and generally harrying Komo, when a third cub emerged from the den and started to nurse too! We named Komo's third cub Enterprise, and were very excited to get to see a triplet litter. Enterprise was significantly smaller than his siblings, and it was clear that he couldn't keep up with their play or compete with them for access to Komo's nipples. 

Voyager and Star Gazer nursing from Komo, while Enterprise looks on.
However, Komo gently chased her larger cubs off, to allow Enterprise to nurse.

Enterprise nursing
Komo seemed to be protecting Enterprise from the rough play and aggressions of his larger siblings, and wouldn't let them get too close.

Komo, keeping an eye on all three of her babies

Unfortunately, that was the only time we saw Enterprise. He just couldn't keep up with Voyager and Star Gazer, who are very robust, healthy kids.

This week, though, we have another set of triplets! Heidi and I found Ink, a mom from North clan, hanging out with three babies at the communal den. For most of the session, Ink was sitting in the den hole, keeping her babies away from the older cubs and from the prying eyes of hyena researchers. Eventually we saw some little black cubs poking their heads out of the den, and then they started to nurse. Because they were still mostly in the den hole while they were nursing, it was hard to see, but at one point Ink picked one of the nursing cubs up in her mouth and proceeded to hold the little guy in place with her front leg and groom him. Even when she was done grooming, she kept holding on to him with her front leg, which allowed a third cub to come up from the den and start nursing!

Ink, grooming her cub, and preventing him from fighting with his siblings.
Video by Heidi Rogers

So far all three cubs look healthy and large, and Ink seems to be doing her best to make them share. It's a long shot that all three of them will make it, but for now they are providing us with a lot of adorable play time and a lot of contentious debate over which comic strips to name them after.

Smale, L.; Holekamp, K. E.; Wedele, M.; Frank, L.G.; & Glickman, S. (1995) Competition and cooperation between litter-mates in the spotted hyaena, Crocuta Crocuta. Animal Behaviour. 50:3. p. 671-682.

1 comment:

kay said...

This is very exciting!

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