Flamingos of the Andean Plateau

Marita Davison investigates how flamingos influence a lake's biodiversity

By Marita Davison

Physical exertion at an altitude of more than 14,000 feet would make anyone short of breath, I was sure of it. Gusting Andean winds could make the simplest of tasks virtually impossible. I told myself these things—as my lungs screamed for a decent gulp of air and my hands were numb and fumbling—to stay focused, to somehow, albeit slowly, keep moving. The advancing nightfall and declining temperature brought a sense of urgency to my motions. I looked to the field crew and recognized the same resolve in their steady movements. The wind hummed continuously, loudly, punctuated only by distant chururu and jututu vocalizations emanating from our wary companions—the flamingos who, throughout the course of the afternoon, had kept their distance from us.

Bolivia's Laguna Colorada is home to Puna (or James's) Flamingos and Andean Flamingos, as well as small populations of the more widespread Chilean Flamingo (not pictured).

Marita Davison

We were laboring at Laguna Colorada ("Red Lake"), a 60-square-kilometer saline lake located in the heart of Bolivia's desertic Andean plateaus, the sparsely populated puna. Laguna Colorada is the main attraction for visitors to the Eduardo Avaroa National Fauna Reserve, Bolivia's most highly visited national park. The reason? Flamingos—thousands of them. Laguna Colorada is the most important breeding site for the elusive Puna Flamingo (Phoenicopterus jamesi, locally known as chururu), which was considered extinct until its rediscovery at this very site in 1957. Colorada also harbors large breeding colonies of Andean Flamingos (P. andinus, locally named jututu). Together, these two species are the rarest and least known of the world's flamingos. Only recently have researchers—aided by improved access and infrastructure—begun to intensively study these populations, tucked away in far corners of the harsh puna landscape.

As part of a team of biologists from the Bolivian chapter of the Wildlife Conservation Society and BIOTA, a local conservation nongovernmental organization, I traveled to Laguna Colorada in March 2007 to begin my Ph.D. work on the poorly understood Andean salt lakes of Bolivia, my home country. Inspired by the work of early pioneers (the likes of Alan W. Johnson, William Conway, and Stuart Hurlbert), I arrived with a specific plan: exclude flamingos from portions of Laguna Colorada to measure their effects on ecological processes within the lake. Studies conducted by Hurlbert in the 1970s and 1980s had indicated that flamingos have big impacts on lake communities. When flamingos were excluded, Hurlbert argued, invertebrate and algal assemblages shifted in composition, becoming more homogeneous. My goal was to conduct a similar experiment investigating whether flamingos influence the most fundamental biological process underlying any ecosystem: primary production, in this case, the growth of algae.

And so we found ourselves toiling away as the Colorada evening was giving way to another biting puna night. We were building "exclosures"—flamingo fences—to keep chururus and jututus (but not other birds) out of plots in one of their favorite foraging grounds along the north shore. Both species forage by filtering algae (located in the shallow water column or on the sediment surface) through a set of horny plates lining their beaks. These plant communities form the base of the Laguna Colorada food web; their growth supplies nourishment for countless lake organisms which, in turn, become food for other organisms, and so on. In the case of chururus and jututus, they are presumably the birds? sole food source.

Because of their dependence on algae and their role as main grazers in their habitats, chururus and jututus are probably vital in controlling primary production within a given lake. Primary production can shape patterns of biodiversity and species composition; therefore, the influence of flamingos on primary production may provide the basis for explaining the relationships Hurlbert observed more than 20 years ago.

Marita Davison takes a sample of sediment with a surface layer of algae as part of her study on how flamingos influence the lake's biodiversity by affecting the production of algae, the food base for the lake's wildlife.

Jennifer Moslemi

After a grueling afternoon of building exclosures and only six days during which the flamingos had been excluded, we found a visible indication of what we were looking for, one that was perceptible upon a simple glance inside the exclosures themselves. The sediments surrounding each exclosure (which had been actively grazed by flamingos) were a heterogeneous gray-black, with fresh footsteps and beak marks evident everywhere. Inside the exclosures, however, the sediments were undisturbed, a thin, virtually uniform layer of green—algae—resting on the surface. This observable difference was substantiated once we took samples back to the lab: excluding flamingos more than doubled the amount of algae found on the sediment surface.

The main implication of these preliminary findings is that chururus and jututus are probably central players in sustaining biodiversity within their lake habitats. As focal organisms in the food web, they may be highly responsible for maintaining it. This is particularly significant in light of increasing pressures from unregulated ecotourism, which may have damaging effects on the entire ecosystem. Understanding the complexities of how these lakes function is crucial for maintaining their ecological integrity and ensuring that they provide opportunities for sustainable ecotourism into the future.

All of these thoughts were present in my mind as we finished building the last of our exclosures. The crisp Andean sky had shifted its crimson glow to dim shadows. My lungs wheezed and my hands ached. Amid the discomfort I reminded myself that this excruciating labor would uncover some understanding of these puna lakes and their associated biological communities. I knew it would be well worth the effort.

Researchers conduct a census of flamingos at a lake in southwestern Bolivia.

Jennifer Moslemi

Marita Davison is a graduate student in Cornell's Department of Ecology and Evolutionary Biology. Her advisors are John Fitzpatrick, director of the Cornell Lab of Ornithology, and Alex Flecker, associate professor in Ecology and Evolutionary Biology.

For permission to reprint all or part of this article, please contact Laura Erickson, editor, Cornell Lab of Ornithology, 159 Sapsucker Woods Rd., Ithaca, NY, 14850. Phone: (607) 254-1114. email: lle24@cornell.edu