Friday, July 3, 2009

Serengeti's Most Important Critters

“Stop. Stop! Simama tafadhali,” I yelled. We were on a dirt track heading south from Lake Ndutu when I spotted it.

Startled at my outburst, Joshua, my driver guide, slammed on the brakes and we skidded to a stop in a cloud of dust. The other two vehicles behind us, part of our group, also stopped. Everyone looked around, puzzled, for there were no animals nearby – no lions lurking in the grass, no gazelles or wildebeest grazing. Just empty grasslands rolling away to an infinity of sky.

I got out of the vehicle and announced to all the photographers in my group that I was about to give them the opportunity to photograph one of the most important critters on these plains. They looked skeptical, glancing around and seeing nothing but grass. Not a photo op in sight.

They exited the vehicles and as they gathered around, I pointed down at the ground. There, unfolding before their eyes, was a preposterous scene: a perfectly round, golf ball-sized piece of dung being pushed by a large black beetle. It was comical to watch as the scarab, using hind legs and balanced on front legs, pushed the ball in a seemingly aimless way, being diverted by grass clumps, stones, sticks and other impediments. Another beetle, offering no help whatsoever, was attached firmly to the ball and was rolled over and over as the first beetle pushed it about. The second beetle was obviously the foreman, we concluded, who probably was shouting, in unheard beetle language, directions to the pusher: “No, to the left. More. More. No, now go right you dummy, . .”

At times there seemed to be little progress as the ball was halted by a clump of grass. To get around it required a change of direction, but neither beetle seemed to have any one direction in mind. A incredible the amount of energy was being expended by this little insect pushing something that weighed many more times its own weight. Despite the appearance of a scene out of an old Keystone Cop movie, eventually the pushing beetle found what it was looking for, with or without help from its hitchhiker. It began excavating beneath the dung ball and soon disappeared. Slowly the ball sank into the pit being created and finally the very top, with its still-clinging passenger, was below ground level. Then it disappeared under a mound of dirt.

Accompanied by lots of laughter, dozens of pictures were taken. I doubted that too many of them would be shown to friends back home (“You mean you traveled thousands of miles just to photograph a dung beetle?”) But on the serious side, before we left the scene someone asked why I considered this to be one of the most important animals on the plains.

I explained. For one, consider these facts:
One million three hundred thousand wildebeests, give or take fifty or a hundred thousand.

Two hundred thousand zebras, more or less.

Almost four hundred thousand gazelles.

Add elephants, impala, kongoni, buffalo, and a few more miscellaneous fauna.
Total them up and it’s well over two million animals, all eating grass and all of them – well, let’s put it this way. If it weren’t for dung beetles, we’d be up to our armpits in you-know-what.

But in truth, the dung beetle is more than an insectivore pooper-scooper. That’s a secondary benefit. It turns out these little critters do have a purpose in mind for that ball of shit. When it’s buried, eggs get laid in it and the new generation of dung beetles starts out feasting on this nest egg (so to speak). In the process of this, the soil of the grasslands gets aerated and fertilized. While we only watched one dung beetle, if you multiply that act by a few million, you begin to realize that this is a massive operation. Researchers estimate that 15-20% of the soil on these plains was made up of buried dung. One researcher counted, in one pile of elephant dung, 16,000 beetles (an astounding bit of dedication, spending all day poking around in piles of dung and counting beetles). On average one beetle might weigh, say, 2 grams, and it can move 250 times its weight of dung in one evening (according to those dung researchers). That’s 500 grams of dung - about one pound. Multiply by just those 16,000 beetles, and we are talking eight tons of dung being buried. So it’s easy to see that hundreds of thousands of dung beetles working the night shift can move and bury dozens of tons of fertilizer. Even with the best of modern agricultural technology, we humans would be hard pressed to duplicate that feat. And yet this seemingly insignificant, even comical (to us) insect is what keeps these grasslands healthy and without healthy grasslands millions of herbivores might not survive.

We still have some spaces on our photo and natural history safari in January 2010 (limited to 10 participants). Next year marks our 25th year of running photo safaris there. If anyone is interested, information here: www.wildernessphotography.com/tanzania.htm


A one minute video - dung beetle in action:

video

2 comments:

  1. Dung beetles, one of the least appreciated, and most hard-working little guys on the planet! Great to find your blog. Heading to TZ in August for a tropical biology course near Amani. Ever been up that way?

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  2. Kirsty, I have not been to Amani. That's in the region of the Usambara Mts. I understand that it's a richly biodiverse area. Have fun. Go dung beetles!

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