Sunday, August 14, 2011

Wildebeest Crossing in Northern Serengeti

I try to avoid writing about big things on this blog, and would rather concentrate on little things that many people miss. On the last trip, this sighting in the northern tip of the Serengeti, on the Mara river will definitely be marked as one of the best wildlife sightings for me this year.
3 channels of wildebeest begin the crossing
The wildebeest had gathered on the far bank of the river, the huge grass fire on the Maasai Mara behind us dwarfed by a building thunderstorm beckoning the wildebeest to cross. The wildebeest migration is driven by their need for water and green pastures, and as we all know, the grass is always greener on the other side.
Emerging around the vehicle
When the rest of the Serengeti is drying up, the wildebeest head north towards the Maasai Mara and Lamai wedge. These areas experience rain because of their proximity to Lake Victoria and the prevailing winds. Fires, which frequent the area at this time of year, are either lit by poachers to distract rangers, or by rangers in with their ecological fire regimes. The fires clean out the dry less nutritious grass and there is some evidence that the smoke precipitates the rain in the same way that farmers shoot Silver Iodide smoke to get rain in other parts of the world. The released nutrients in the ash and water from the rain have an amazing effect on the grass which sprouts a green lawn known as the green flush. (Read more about the effects of fire on Savannah’s here)

I wish I had a sound recording of the splashing and gnu-ing.
At about 4:30, the first wildebeest dove into the river provoking the rest of the herd to follow in what is one of the largest wildebeest crossing I have ever witnessed. Parked slightly downstream we watched as the current slowly drifted the crossing herds closer to our vehicle until they were emerging up the bank on either side of the car. I estimate over 30,000 wildebeest crossed in the 2 ½ hrs we’re there.

Wednesday, June 15, 2011

A Yellow-striped Blind Snake

“Ethan, I have one of your special friends to show you” are Colin’s words as he walks up to me cradling this jewel in his hands. Tarangire National Park is known for its snakes and we’ve seen Black Mambas, Puff Adders, Green Tree-snakes, Sand-snakes, Rufous-beaked Snakes, Boomslangs, and encountered Black-spitting Cobras and watched Rock-Pythons climb trees. Considering events in the past few months, and the fear of snakes that was instilled into me as a child, why am I so fascinated by these animals? Well let’s start with this amazing little guy.
No, its not a bracelet.

It’s small, about 30 cm long, and blind. It has a big yellow stripe down it’s back and can you guess what it’s called? A Yellow-Striped Blind-Snake. Its Latin name is Rhinotyphlops unitaeniatus.

Blind-snakes (Typhlopidae) belong to a group of snakes that are considered primitive, yet highly specialized and they are closely related to another family called the Worm Snakes (Leptotyphlopidae). They first appear in the fossil record 135 million years ago and since their general body plan hasn’t changed much since then, it is obviously a highly successful one.

Check that helmet and can you see it's tongue?
Blind-snakes and worm-snakes are blind because they live under the ground and don’t need to see. Their bodies feel tight, and are cylindrical with a large scale over their foreheads somewhat like a helmet. This acts as a battering ram when they push through the soil. Their tail ends in a spike (caudal spine) that they use as an anchor for pushing through the soil. I think it’s fascinating that these two groups of snakes have special glands in their foreheads whose function no one has yet figured out.

According to the map in “The Field Guide to Reptiles of East Africa”, the Yellow-striped Blind-Snake isn’t recorded as far south and west as Tarangire National Park so this may well be a first.

The tail ends in a spike- note the Ant-lion pit on the left.
What does it eat? Well, like most Blind Snakes, its diet consists of termites and ants.

Its quite a sharp spike.
Read more on our blog aimed at guides.

Thursday, May 5, 2011

Spiny Flower Mantis

One morning in between lessons in the bush in Tarangire with 10 guide trainees this April, this beautiful creature caught my eye hanging out on a stalk of grass next to a flower; no doubt waiting in ambush for the insects visiting the flower. I got my camera out and snapped a couple shots wishing I had a macro lens to get in really close. The Spiny Flower Mantis, known to entomologists as Pseudocreobottra wahlbergi, particularly fascinated me because of the asymmetrical swirl pattern on its back. The majority of multi-cellular animals belong to a group of animals called the bilaterians, meaning they are supposed to be bilaterally symmetrical. Of course, another lesson from the bush- never jump to conclusions. As the mantis decided it had had enough of me sticking my Nikon in its face it flew off revealing that it was in fact symmetrical with the eye spots on both wings. Eyespots are far more common on moths of the Saturnid family, and their purpose is a form of mimicry, making the moth look like the face of an owl. I wonder if the swirly eyespots on this mantis served the same purpose or if their beauty served to dazzle their predators.

Tuesday, February 8, 2011


Driving around Mwiba ranch you can’t help yourself but wonder what all the different sounds are that you hear. Leaving aside wilddogs whooping and yipping, lions roaring, leopards grunting, buffalo bawling, the impala alarm calls, there are all the piercing noises made by insects and frogs. Grant and I decided to set off one night, grabbing our maglites we drove to the nearest stream took off our shoes and waded in.

Frogs require water to lay their eggs in and males hang around in the water, on vegetation around the water calling for females to come and mate. Some have developed fantastic large airsacs in their throats that the blow up to amplify the sounds that they make. It’s a competition, so their sounds tend to be extremely loud.

The first 10-15 minutes of wading around in the water were quite frustrating at the frog’s amazing ventriloquy abilities Frogs are also surprisingly camouflaged, and it takes a few minutes before your eyes become trained to pick them up from wherever they are calling. Part of the reason their so hard to see is because most of the time they stop calling when they sense a predator (or are blinded by a maglite) so you have to sit still and wait for them to start calling again. The other problem is that once they’re in the water they are nearly impossible to catch.

Nevertheless, during the 3 nights we went frogging we managed to catch 5 different species (+ 2 species seen on walks).

The most beautiful was this East African Tree Frog (Chiromantis petersi) also known as an East African Foam Nest Frog. They get their name from the fact that they don’t spend most of the time in water but end up hoping around on trees and as you can see from the photo they blend in very well. In fact they can change color from dark to almost white. Foam nest frogs don’t lay their eggs in water, but when the males climbs on the females back as she is laying eggs, he starts to move his legs whipping up a mucus excretion into a foam that protects the fertilized eggs. It’s a skill that has intrigued scientists studying it because making a foam nest suitable for protecting eggs has interesting medical implications like protecting burns from drying out and protecting wounds in emergency care. If you’d like to read more about this check out this link

East African Foam Nest Frog (Chiromantis petersi)
The other star of the night was a Muller’s Platana or Muller’s clawed-frog (Xenopus muelleri) that Grant managed to catch because it has trapped itself in an elephant footprint that had water in it. In contrast to the Tree frog, this Platana spends most of the time in the water. I think Platanas look quite amusing, but I wasn’t so amused when I tried to grab one and it swam just out of reach taunting me to try again- another miss. (No wonder herons have 27 vertebrae in their necks- arranged to form an S that straightens like a rocket to catch frogs). These funny looking frogs can actually call from underwater and it sounds like someone knocking a spoon against a pan. (photo coming soon)

The other frogs we found were- the Tremolo Sand Frog- (Termopterna cryptotis), a Reed frog (Hyperolius sp. prob. H. glandicolor), and a Puddle frog (Probably Phynobatrachus acridoides or P. natalensis). Unfortunately, species identification is quite difficult unless you know the sounds and the best we can do using the South African sound recordings is confirm identification to the genus level. Thanks to Grant Burden for getting me in the water with him and keeping me from getting too frustrated with the keys, and to David Moyer for looking at photos and helping with Id.  

Tremolo sand frog (Termopterna cryptotis)
Reed frog (Hyperolius sp1. prob. glandicolor)
Puddle frog (Phynobatrachus acridoides or P. natalensis)
Reed frog (Hyperolius sp2. prob. viridiflavus). Photo credit: Colin Beale Jan. 2011.
Young African Bullfrog (Pyxicephalus adspersus). Photo credit: Colin Beale Jan. 2011.

Tuesday, December 7, 2010

The Longest Insect in the World?

On a cold morning in June 2010, sitting in the back of an open vehicle in Tarangire National Park, the guide trainee who was attempting to impress us with his guiding skills stumbled upon this magnificent creature. I had never seen a stick insect so long and my first thought was that it could be a new species.

After taking photos with my hand in the picture for size comparison (and we didn’t play any visual tricks), I decided to try to hold it. Carefully reaching in, I put my fingers on either sides of its thorax to pick it up. This way, I thought I would be able to hold it without hurting the insect. In a rapid movement it lifted the two scales that look like thorns and spread its wings, which startled me, so I quickly pulled my hand away.

Stick insects belong to an order called Phasmatodae. They are vegetarians and are most active at night- when it’s even harder to see them. This particular individual comes from a genus called Bactrododema or Palophus.

Check out the "thorns" just like on a Wait-abit-Acacia (Acacia mellifera). If you look carefully at the "thorn" above the finger after the joint you can see the insects eye. 

My hand is about 8 inches long- that means the stick insect is at least 16 inches long.

Without knowing anything about the specific insect, I was excited to be able to describe two defense strategies that this insect uses. Stick insects are actually one of the most vulnerable insects. They can’t jump, they can’t fly, they don’t bite, and they don’t sting so they have to rely on a different method to hide from their predators- mainly insect eating birds. The strategy that most use is merely camouflage or cryptic coloration. They blend into the environment and mimic either grass or twigs and as a result we hardly ever even notice them.

When we found this giant stick insect, it was doing what stick insects do and blending. It had its front legs and antenna stretched out in front of it, and was holding its body rigid, just like a stick. Even when we touched the growths on its body that looked like thorns it remained completely still, until I tried to pick it up. If pretending it was a stick wasn’t going to work, it was going to have to do everything it could to scare me. Spreading its wings quickly, accompanied by a sound as though someone was crumpling some newspaper, was enough to make me quickly move my hand away from the insect. Looking carefully at its wings you can see that they are torn and it’s obvious that this insect doesn’t use its wings to fly. I expect the flash of color also serves to visually startle its predators.

Bactrododema sp. aka African pretender.