…and they’re telling us more than just, “Whoop!!! Come check out this great wildebeest kill!”
In my last post regarding our Petridish project, “A Sentinel for African Ecosystems”: http://www.petridish.org/projects/a-sentinel-for-african-ecosystems, I wrote about how we were going to monitor space use in spotted hyenas using GPS collar technology.
Well here they are!
20 GPS collars ready to be deployed on spotted hyenas.
Manufactured in Germany, these collars come to a total weight of 1kg (~2.2 lbs), and rest on the neck of our study hyenas when deployed. Although this may seem heavy, this weight is much smaller than the recommended 3% weight of the animal (spotted hyenas can weigh up to 80kgs!). If the title has intrigued you, each of these collars functions like a cell phone. They have a SIM card and send text messages of their GPS locations through the cell phone towers back to our ground station in camp. Each day we can then download the points and visualize them on programs like Google Earth. For the Sentinel project, we’re deploying these GPS collars on 3 high ranking, and 3 low ranking hyenas in our study clans.
If you recall from the many blog posts about the dominance hierarchy in crocuta, spotted hyenas live in a highly structured rank hierarchy. In this hierarchy, every adult female within the clan knows where she stands, who is above her, and who is below her (in other words, who she can take food from, and who can take food from her). However, not only does rank determine priority access to food, previous research has shown that rank influences where hyenas like to spend their time in the territory. An easy way to think about this would be something like: if you are low-ranking, why would you want to hunt or kill something near other, higher-ranking, animals who would just take all of the tasty bits as soon as you take down a wildebeest?
Spotted hyena eating a wildebeest.
Needless to say—high ranking and low ranking individuals within the same clan show very different areas of use within their territories, and it is important to monitor both for the Sentinel project. Understanding this variation will strengthen our ability to monitor spotted hyenas as a sentinel species. For example, perhaps low rankers indicate certain aspects of ecological change better than their high ranking clan-mates.
We’ve started darting and deploying some of these collars here in the Masai Mara this summer. In our South clan, we were fortunate to find the dominant female, Clovis, sleeping out in the open. We took this opportunity and darted her, deploying our first collar in her territory.
The dominant female in South territory sporting her GPS collar.
Since her darting, we’ve been receiving points of Clovis’s locations hourly from 4PM-10AM (when hyenas are most active), in addition to a resting location at 1PM in the middle of the day. Take a look at her movement!
The GPS locations we’ve received from Clovis’s collar thus far.
The green square is where we had darted her, and the red square is the last location that we’ve received.