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Bat-Survey Lesson No. 42: Don’t Step on Any Lions

A glimpse of one of Sesfontein's springs where Theresa and Archie netted for bats (Photo by Theresa Laverty)
A grand old tree stands by one of Sesfontein’s springs where we netted for bats. (Photo by Theresa Laverty)

In Among the Big Predators

While my last week in the field was not my most successful in terms of sheer bat numbers, it at least highlighted the challenges of working in this part of the world.

Two days after netting in Sesfontein, my local field assistant, Archie Gawusab, and I were investigating Awaxas Spring in the Palmwag Concession as a potential netting site. We had walked around the perimeters of two of the three small pools, but I wanted to see the last one before deciding where exactly we would net that night. Less than a minute of walking later, Archie jumps, turns, and comes thrashing through the mud. He had nearly stepped on a lioness resting in the dry, waist-high grass, which explains the low growl I heard when Archie was startled. Understandably, we were a bit jumpy that night even through our only large mammal visitors were two black-backed jackals.

The following evening, I had just released my first bat when a lion vocalized way too close for comfort. There must have been a fresh kill in the area, so we packed up very quickly despite my desire to stay for more bats and more data. We ran into lots of fresh leopard tracks at another site later in the week where we also spooked a spotted hyena in the daylight, so we decided not to net down in that canyon. I finally caught some horseshoe bats in my last week though, which are a group of Old World bats that I suspected to find in the area, but had not been able to catch thus far.

Laverty_RHDA
Darling’s horseshoe bat (Rhinolophus darlingi) may not seem like much of a darling, or look all that much like a horseshoe, but, there you have it. (Photo by Theresa Laverty)

Fear of the Fear of Bats

When asked what I am researching in Namibia, I reply with the term “vlermuis” in Afrikaans, which literally means “wing-mouse.”

It seems to be uncommon to hold a conversation about bats in the northwestern corner of the country and often requires further explanation. “No, not crocodiles (there are no crocodiles in this part of the Namib Desert anyhow). Tell them bats are like birds, but they fly at night,” I suggest to my local field assistant, Archie Gawusab.

Most people hear the word and respond with a blank stare, wondering why a young woman like me would be interested in such creatures. Others immediately scrunch up their faces at the term since bats are considered to be bad luck for some—much like seeing black cats or walking under a ladder are in the United States.

Given all of this, I had been a little worried when I invited some of Archie’s children to come watch us net in Sesfontein. My fears became completely unwarranted though—the girls loved the bats! With that little trial completed, I am really looking forward to arranging more community outreach programs when I return to Namibia with a focus on the the various research projects that take place in the northwest.

Young Explorer Theresa Laverty explains a bit of bat morphology to her field assistant's daughters (Photo by Archie Gawusab)
Here I am, explaining a bit of bat morphology to the daughters of my field assistant, Archie Gawusab. (Photo by Archie Gawusab)

The Namib Desert: A Land of Extremes

My fieldwork ended on January 17th, a cold evening in Palmwag with way too much moonlight to successfully catch any bats.

I returned to Windhoek the following day and had a whirlwind of errands to accomplish that week before flying home. Upon reaching the U.S. again, I heard the Hoanib River came down in full flood at a force and volume not seen in many years the day after I left the country.

Just two weeks previously when I last was on the river, only a few small springs remained that were quickly drying up. The new water will transform the vegetation and bring about a flush of insects and new life. Wildlife will disperse, but floods in the desert are temporary and it is only a matter of time until the riverbed is dry and cracked and the water is once again concentrated in a few small areas.

I heard the flood cut through the dunes of Skeleton Coast National Park, but ran out of steam in the mouth of the river just a quarter of a mile, or a few hundred meters, from the ocean. Desert life is full of extremes.

Desert elephants enjoy a sip of water after another hot day in the Hoanib River (Photo by Theresa Laverty)
Young and old desert elephants enjoy a sip of water after another hot day on the Hoanib River. (Photo by Theresa Laverty)

Purpose of this Pilot Study

I spent my winter break in the northern Namib Desert piloting my Ph.D. research. Specifically, I wished to address:

1) how herbivore communities differ between the dry river systems,

2) if there appears to be differences in bat communities across the different river systems, and

3) what factors might be responsible for these differences in bat communities.

Due to the large difference in elephant population densities in particular between the river systems, I am interested in linking the communities of some of the largest terrestrial mammals (the elephants) to some of the smallest (insect-eating bats).

Given their small size, high mobility, and nocturnal behavior, bats are traditionally very hard to study, yet play an important role in controlling insect populations. Like elephants, they are what ecologists call “k-selected” species—ones that reproduce slowly and have long lifespans.

For instance, some bats are known to live over 30 years in the wild and typically have 1-2 pups per year. As conservationists, we tend to focus primarily on the k-selected species since those species take longer to rebound after declines given their reproductive constraints. Therefore, it is important we do not overlook bats when prioritizing species due to their conservation concerns.

Schlieffen's twilight bat, Nycticeinops schlieffeni (Photo by Theresa Laverty)
Bats come in all shapes and sizes. Most insectivorous species, like Schlieffen’s twilight bat (Nycticeinops schlieffeni) pictured above, are small enough to fit easily in the palm of a hand. (Photo by Theresa Laverty)

An Arid Eden

I am already looking forward to returning to the Namib now that my pilot season is behind me in hopes to tackle the bigger food web questions that motivated this study. It is never an easy transition returning from the field, but I should be back in desert northwestern Namibia before the year is up. I can surely promise you that this “arid Eden”—the title conservationist Garth Owen-Smith uses for northwestern Namibia—will always be playing in the back of my mind.

There is nothing like a Namib Desert sunset when preparing for a night of netting for bats (Photo by Theresa Laverty)
There is nothing quite like a Namib Desert sunset when preparing for a night of netting for bats. (Photo by Theresa Laverty)

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Comments

  1. Terry Pritchard
    Devon, UK
    August 10, 6:13 am

    Dear Theresa. I will be visiting Botswana and Namibia in November. I’ll be taking my bat detector which i use in the UK
    (9.0 – 138.0 kHz) I cant find any information on the internet about bat frequencies in Africa that i am likely to encounter. Any ideas? Any info greatfully recieved. Yours sincerely Terry Pritchard.

    • Theresa Laverty
      August 11, 9:03 am

      Hi Terry,

      That’s great news. I tend to use the book “Bats of Southern and Central Africa” by Ara Monadjem et al. for a good idea of call frequencies. The book includes a screenshot of a sonogram for many of the common species that are encountered although frequencies may shift slightly for the same species in different locations. I’m working on forming my own call library for Namibia’s coast, but don’t have all that information together just yet to share. I hope you have a great trip this November and please look me up if you pass through Namibia!

      Best,
      Theresa

  2. Terry Pritchard
    Devon, UK
    August 10, 6:11 am

    Dear Theresa. I will be visiting Botswana and Namibia in November. I’ll be taking my bat detector which i use in the UK
    (9.0 – 138.0 kHz) I cant find any information on the internet about bat frequencies in Africa that i am likely to encounter. Any ideas? Any info greatfully recieved. Yours sincerely Terry Pritchard.

  3. Joel Berger
    Fort Collins, Colorado
    June 13, 2015, 10:20 pm

    Fun stuff Theresa and also important… nice script BTW.

    Good luck.

    JB