After three weeks of traveling through northwestern Namibia in search of water where I net for bats, I now have a much better appreciation for the term “desert oasis.”
Driving north on the heavily corrugated gravel road from Sesfontein to Puros last week, we passed through some extremely arid areas. Upon reaching Puros, however, we reached the beginning of a flowing section of the Hoarusib River—a stretch of water about 7.5 miles (12 km) in length—accompanied by the wealth of biodiversity you find around desert water.
For three nights, field assistant Archie Gawusab and I netted along this stretch of ankle-deep water. We caught a diversity of vesper bats and molossids (bats with long, free-hanging tails), while thankfully avoiding the capture of a confused Hartmann’s mountain zebra just outside of Puros. Now that the moon is waning, the skies are finally getting darker, landing us more bats in the net.
Given the permanence of water in this area, quite a few cattle wandered in and out of the riverbed canyon each day among the springbok, oryx, and elephants. It’s rare to find livestock so far down these rivers, but the flowing water and riparian vegetation supports them in a region that receives on average about three inches of rainfall per year.
While working in the evenings, small flies and gnats filled the air and I am pretty sure I inhaled several pounds of bugs while processing bats next to the calmer portions of water in the river. It is worth mentioning that the flood lines in the dry riverbed downstream of this flowing water were well above my head, a reminder of the dramatic impact that flash floods can have. Luckily, we did not experience the Hoarusib River at its extreme.
After those three nights, water was much harder to come by as we made our way back to the Hoanib River (the area where we began netting in late December). While searching around at an old spring up the Mudorib River, we spooked off a pride of lions from the shade and watched them cross the golden, grassy hillside. The water was gone, however, with just a few wet rocks at the bottom of holes the elephants must have dug as the site dried out.
After two days searching for water, I ended up just re-netting at some of the previous Hoanib River sites to check for any indications of change in bat species use or diversity over time, but even one of our first field sites had dried up forcing us to move about a quarter mile (300 meters) upstream instead.
We made it back to Sesfontein this morning (January 11, 2015) and will be re-netting at the spring in town tonight. With just one week left in the field, I recently completed our rough field schedule and I am preparing for the return to Windhoek.
It is difficult to believe I will be sitting in class in Montana again in just two weeks time. It is still too early to contemplate that notion, however, so best to get back to focusing on the matters at hand: the areas where people, their livestock, and big (and small) game all share the same water holes. It sure will be hard leaving the Kaokoveld.