By now, you have probably heard of this silly (but hilarious) video that’s been making the rounds of the interwebs lately:
It’s pretty catchy, not just because it’s ridiculous, but because it’s a pretty good question. I mean, how many of you out there have actually ever heard a fox?
The sounds of the bush are one of the many, many things I miss being back here in civilization. From my slightly sketchy corner of Saint Paul, I hear fire crackers and unmuffled engines roaring. Occasionally I get chattered at by an angry squirrel in the back yard. But that’s about it. Nothing like the otherworldly chorus of the Serengeti savanna that Lucy so beautifully described.
The sounds really are incredible and often unbelievable, and I thought I’d share some of them with you. I couldn’t actually figure out how to upload audio files, so I scoured Youtube for the best audio clips I could find and embedded them as videos here.
Zebras: Nothing like horses, these stripy equids sound something like a braying donkey crossed with a barking dog.
Wildebeest: I believe that somewhere in the annals of Zooniverse blogs, there is an audio or video clip of me doing a wildebeest impression. This is better.
Hyenas: Despite being hell-bent on devouring all of my camera traps, these guys are pretty cool. They have a rather large repertoire of very…unusual…vocalizations that are used to communicate in a number of situations. The whoop, which you hear at 0:05 and 0:55, is a long-distance call often used to rally scattered clan members. The laugh at 2:33 is a sign of nervousness or submission. Similar to human voices, hyena vocalizations are individually recognizable to clan-mates. To learn more about hyena vocalizations, check out this blog by hyena expert and director of Masai Mara’s long-term hyena project, Kay Holekamp.
Lions: And finally, for the best, non-hollywood lion roar, scroll about halfway down through our lion research center’s page. This is what they really sound like.
I’ll take any of these noises over the sounds of the city any day.
Last month, I wrote about how, despite lions killing cheetah cubs left and right, they don’t seem to be suppressing cheetah population size like they do for wild dogs. And, that despite all this killing, that cheetahs don’t seem to be avoiding lions – but I didn’t have radio-collar data for wild dogs.
Well, now I do!
Although we’ve had collared lions continuously since 1984, Serengeti cheetahs and wild dogs were only collared from 1985-1990. We worked with Tim Caro, former director of the cheetah project, to access the historic cheetah data a year ago, but it was only a month ago that we finally tracked down the historic wild dog data. Thanks to a tip by a former Frankfurt Zoological Society employee, we found the data tucked away in the recesses of one of their Serengeti-based storage containers – and Craig braved a swarm of very angry bees to retrieve it!
The good news is that the data was totally worth it. Just like we suspected, even though cheetahs didn’t seem to be avoiding lions, wild dogs were. This map shows lion densities in the background, with cheetah (in brown dots) and wild dog (black triangles) locations overlaid on the lion densities.
It’s a pretty cool contrast. Even though lions kill cheetah cubs left and right, cheetahs do not avoid lions, nor do their populations decline as lions increase. In sharp contrast, wild dogs do avoid lions, and their populations also drop as lions increase. Now, that’s not to say that there weren’t other factors influencing the decline of wild dogs in Serengeti, but across Africa, this pattern seems to hold.
Speaking of wild dogs, has any one seen any in Season 6?
I was asked in the comments to last week’s blog post if I could provide some feedback about the results of Season 4. If you felt like you were seeing a lot of “nothing here” images, you’re right: of the 158,098 unique capture events we showed you, 70% were classified as having no animals in them. That left 47,320 with animals in them to classify, and the vast majority of these (94%) contained just one species. Here’s the breakdown of what was in all those images:
Maybe it won’t surprise you that Season 4 covered 2012’s wet season, when over a million wildebeest, zebra, and Thomson’s gazelle migrate through our study area. I find it interesting that hartebeest are also pretty numerous, but I wonder if it’s because of that one hartebeest that stood in front of the camera for hours on end.
This pie chart is based on the number of what we call “capture events,” which is the set of 1 or 3 pictures you see every time you make a classification. Once a camera has taken a set of pictures, we delay it from triggering again for about a minute. That way we don’t fill up the camera’s memory card with too many repeats of the same animals before we have a chance to replace them. But a minute isn’t a very long time for an animal that has decided to camp out in front of a camera, and so we frequently get sequences of many capture events that are all of the same animal. One of the things we’ll have to do in turning your classifications into valid research results is to figure out how to find these sequences in the data automatically.
Here’s a sequence of an elephant family hanging out around our camera for the night about a year ago. (Hat tip to dms246 who put together a collection of most of these images to answer the concerned question of some classifiers who saw just one image out of the whole sequence: is that elephant dead or just sleeping?)
If you’re interested in how I made the above pie chart, keep reading. But we’re going to get technical here, so if algorithms don’t interest you, feel free to stop.