Gorongosa: The Sand Forest

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The road through the Sand Forest, Gorongosa National Park, Mozambique. 

One of the more unique habitats I visited while in Gorongosa National Park this past summer was the Sand Forest, just a short drive from Chitengo camp. It was a strange place to be: the trees and plants were uniquely small and stunted, and the sandy soil was pale and infertile. Most interestingly of all, almost all the trees were covered in long trails and sheets of fine silk. This was not the work of spiders or even caterpillars, but webspinners. These are fascinating insects that have their own order (Embiidina), which is quite unfamiliar to most people. This is because these insects do not eat our crops, bite or sting us, or otherwise cause us irritation. They mostly spend their days hiding away in their silken tents, feeding on lichens and moss underneath. What makes them unique is their ability to spin silk from glands in their forelegs, which gives them their characteristic appearance. Webspinners are also semi-social and live together in small colonies.

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Silken galleries of webspinners on a tree in the Sand Forest. 

I had only seen a webspinner once before (in Florida), so I was excited to try my hand at catching some. Adult females of the species, which is apparently an undescribed species of the genus Embia, are huge and jet black, while nymphs are slender and bright orange. Males have never been seen. Piotr had collected them before at the same locality, but little was known about their biology. What we did know is that they spent the daytime in detritus-filled cracks of branches, and that they were extremely fast and agile. These supercool insects were one of two reasons we came to the Sand Forest.

Our second reason for visiting the sand forest was to photograph an elusive lizard in the genus Cordylus. Harvard undergrad Max Prager, who was in Gorongosa with us at the time, was determined to find one. While Piotr and I scraped silk off branches and picked apart bits of debris lodged in tree branches, Max tore apart the fallen logs that studded the forest floor. Neither of our quarries revealed themselves…at first. We did manage to find a colony of bats high up in a hollow tree, and some termite mounds, one of which Piotr and I broke into with sticks to try and find the queen. She eluded us, but we managed to collect a good amount of workers and soldiers. We also took advantage of the horde of edible insects by eating a few. Although a bit grainy with dirt, I found them palatable, if a bit bland.

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Unidentified termites collected in the Sand Forest. 

After over an hour of searching, we were getting tired. I had collected a few critters, but nothing particularly exciting. I picked at yet another bit of debris and silk in a nook of a tree branch, and suddenly the webspinners were there! About six bright orange nymphs wriggled out of the silk and threw themselves into the air, falling into the leaf litter and skittering in all directions. I frantically grabbed as many as I could, then went back for more, delighted to finally have found them. At the same time I heard an elated cry from a little ways away. Max, too, had captured his target: a beautiful Cordylus. After both lizard and webspinners had been wrangled, we gathered with Piotr to examine our finds. Piotr started talking and then abruptly stopped. His exact words were, “Holy shit. Bees”.

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Nymph of an undescribed species of webspinner (Embia sp.). 

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Girdled lizard (Cordylus sp.).

We stopped in our tracks, and I heard the intimidating sound of an enormous swarm of honey bees approaching. “Stand still, they won’t attack”, Piotr told us. None of us moved as the swarm blew overhead, sounding like a supersonic jet. As Piotr had said, they did not attack us or even descend into the forest, but it was nonetheless a terrifying couple of seconds. The swarm passed, and we started to relax. Suddenly we heard movement in the bushes. We froze, hoping that it wasn’t an elephant or a lion (both of which frequent the sand forest). It turned out to be something much more interesting and quite harmless: a duiker! We had been hoping to see one of these tiny antelopes and here there were two, just strolling by us. None of us had our cameras at the ready, but regardless it was a fascinating sight. After they disappeared into the brush, we photographed the heck out of the Cordylus before releasing it.

All in all it was an unbelievable day. We witnessed a special habitat, saw some beautiful, unique animals, had some excitement, and more importantly, simply had a fun day out in the field. What more could one ask for?

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Webspinner nymph (Embia sp.) on my finger.