Thursday, September 17, 2015

Hyena cub: "Eggs & Milk, please!"

     Imagine for a moment what it would be like to conduct dissertation work that involves watching hyena cubs fighting one another. Now, toss in an egg or some powdered milk and you have the project of Mr. Eli Strauss, a Ph.D. candidate of the lab. As part of my time out here in the Mara, I will be responsible for managing Eli’s egg & milk trials in the Talek West clan. What does that mean, exactly?
This is Flaming Lily. Both her and her brother, Scarlet Hibiscus, are eager participants of egg and milk trials.
     Diverting from their normally angelic nature, the goal of this experiment is to bring about observable aggression in young cubs over a food source: an egg or some powdered milk. Why is watching hyenas fight one another at such a young age important, you may ask? As spotted hyena clans follow a female-dominated (matriarchal) linear hierarchy, questions about how and when their rank is learned have fascinated researchers of the species and of social systems alike. What we know is that around the age of nine-ten months cubs have learned their rank in the clan, but up to that point it remains unclear how cubs are ranked and the rate at which cubs learn their place. By watching aggressive interactions between cubs at the youngest age possible, Eli is studying the state of the hierarchy prior to a cub learning who it is dominant and subordinate to (ranked above and below, respectively). This transitional stage from birth to learned matrilineal (mother’s) rank is extremely valuable in understanding the social structure of the spotted hyena system.
Some of my most lively trials so far have been at Dave's Den. Here I am observing a few of the many cubs denning there. Watching their faces become covered in milk powder or wet with egg yolk has been entirely amusing. Photo: H.Couraud
     What do we do during an egg or milk trial? Watching cuddlesome cubs snap or lunge or bite each other is an undeniably amusing aspect of observing hyenas daily, but there’s more to it than you may be thinking. With a mounted video camera, the egg or milk is deployed from our cruiser and once two or more cubs are feeding, the action begins. We record all hyenas individually, and with young cubs that can be quite the task! Cubs are born with completely black fur, and it isn’t until around three months that shoulder spots begin to form after molting (shedding of their birth fur) and it can be several months after that before we can tell litter-mates (cubs born together) apart. We do our best detective work to distinguish between any visible differences like scarring, missing fur, or ear damage. Once the trial is underway all agonistic (aggressive & submissive) interactions are recorded in the hopes of seeing how young cubs treat one another when competing over the limited (and tasty!) food source.

Photo: H.Couraud
Thanks for reading, hyena-nature-Mara-lovers. That’s all from Kenya for now.

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