Wednesday, November 11, 2015

A Momentous Anniversary

 Last Friday, November 7th, 2015 was a special day. So special, in fact, that I’m just assuming the New York Times is still working on the story which is why we haven’t seen it on world news.

Last Friday, November 7th, 2015 the world’s oldest recorded wild spotted hyena turned 23.

"Growing old isn't for sissies"...and Navajo is anything but that.
First seen in 1992, Navajo is known, in some capacity or another, by every single graduate student, undergraduate, or research assistant that has worked in Talek (and many who have worked in Serena as well). She is a legend in our project; the one and only common hyena that we can all connect over. She has been featured in numerous past blogs, like when she had her last litter of cubs or when she was part of an adult play-bout. She has featured in posts about what hyenas can survive, and seems to have a mini series to commemorate her birthday. 

Whenever we see Navajo, two questions arise:
1.    How does she do it!? This tenacious female is almost twice as old as the best average we have for how old hyenas live in the wild, and the lowest ranking female in the Talek clan – what strategies does she utilize to survive, especially considering how low-ranking she is? 
2.   What kind of thoughts does she have (or not have) about how much has changed since she was born? Because gee whiz has a lot changed!

Though without firm answers for either one, we have several thoughts to mull over.

To the first, we see a trend of lower-ranking hyenas growing too much larger body sizes than other, higher-ranking females. You might wonder - how is that the case, especially considering that a hyena’s rank contributes greatly to their access to food, protection, and energy expenditure?
Ted Williams asserting dominance, standing over Navajo

It makes sense though, when you think it through. In the linear hierarchy of spotted hyena society, a lower-ranking hyena has to give up their food to a higher-ranking individual, should they arrive and demand it. If you’re the lowest-ranking female (read: Navajo), that’s a lot of hyenas who can take your food. So if that is the case, would you want to hunt around everyone else, or on your own? And if you weren’t getting a lot of food at communal carcasses, would you want to kill a measly Thomson’s gazelle, or go for a solid large antelope meal? If you said hunting large antelope alone, you’re on the same mental wavelength as we are. But to take down a large antelope – that’s no small feat. So it begins to make more sense that lower-ranking females have greater body mass; more muscle to chase, hunt, and bring down a large antelope on their own. 
Those are the teeth of someone who has been eating for a looong time.

Also to the first – we don’t think it’s a coincidence that you almost always see Navajo entirely on her own. When group living can confer benefits of protection, and sociality among others, what does the solitary life afford? We believe that in this case, remaining on her own reduces Navajo’s risk of bearing the brunt of aggressions, as well as saves her energy.
Navajo plodding along in 2015

So perhaps Navajo has acquired superior and solitary hunting skills and developed advantageous spatial use patterns. In the time that it has taken her to establish these strategies, what else has changed?

The answer is, quite simply, a considerable amount.

For one, the composition of the clan, and her rank in it has evolved greatly. Navajo was born to the 5th highest-ranking female at the time, Cochise, into a clan of 60 hyenas, putting her in the upper portion of the clan at the time. Over the years (23, may I remind you) Navajo gradually slipped in rank, a result of higher-ranking females having daughters who have daughters etc, and at least one rank takeover, until she came to where she is today – the lowest ranking female (34th) in a clan of 130 (until just recently, more stories to come!).

The clan has undergone at least two major fissions, where one clan splits into at least two distinct clans, if not more. In the first (2000), her littermate, Geronimo, and her split and ended up in different clans. Where and with whom Navajo is ending up after this 2015 fission still remains slightly unclear.

Hyenas and social dynamics are not the only changing factor – the physical space has undergone great change as well. The territory of the Talek clan has expanded, shifted to the west, and now even encompasses a portion of the community lands that include and extend beyond the local Talek town.

Navajo’s life spurs numerous questions: How is knowledge of the borders of each clan passed among the clan? Does Navajo recognize that she spend times in areas she wouldn’t have as a young hyena? Does every member of the clan even know this old lady? How fast does new learning take place? Just how wide are her occlusal surfaces?

In the end, she’s a pretty amazing hyena. As low-ranking as she is, she’ll still exert the dominance she does…

The vultures had the carcass...

...but not anymore!

…as she continues her now-legendary life. Happy Birthday Navajo! 

Posted by, and all photos from, Hadley Couraud

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