I live in Bolivia for the past ten years and am an active birdwatcher. Through both my work with Asociación Armonía and personal travels, I have visited many remote areas of the high Andes. Despite the extensive time spent surveying high-elevation lakes and wetlands, I have never encountered the Horned Coot. While this is anecdotal, I find it notable that even after visiting many sites where the species has historically been recorded, I have only observed Giant Coots, not Horned Coots.
In 2024, I participated in a Diademed Sandpiper-Plover (Phegornis mitchellii) census and witnessed widespread drying of high Andean bogs and lakes. This drying could be attributed to the severe El Niño-induced drought during the 2023–2024 season. However, it may also reflect longer-term changes caused by increasing lithium mining activity, which is expanding across several regions of the high Andes. In addition, overgrazing by large populations of domestic llamas may be degrading wetland quality and water availability.
I believe that the ecological changes occurring in remote Bolivian high Andean ecosystems are being significantly underestimated. The combined impacts of climate change, mining, and livestock pressure may be altering hydrological systems and reducing habitat quality for species like the Horned Coot. While I do not have quantitative data on Horned Coot population trends in Bolivia, the fact that I have not encountered the species at historically known sites over a decade of high-elevation fieldwork suggests a potential decline that requires further investigation.
We have been studying horned coots at the Vilama wetlands for a couple of years, where the largest aggregation has been recorded at Lake Pululos. We are currently working on two manuscripts focused on the species’ reproductive biology. Horned coots apparently do not reproduce every year and are highly nomadic and congregatory, relying strongly on couple of key lakes in Chile (Miscanti and Miñiques) and Argentina (Vilama). These seem to be strongholds particularly during dry years associated with ENSO events. Recent evidence also shows strong declines in lake area at Vilama in the last 30 years driven by reduced precipitation (Casagranda et al. 2019, Santamans et al. 2021). These changes can be accelerated by mining, particularly in Argentina, where there has been an explosion of mining projects on lithium and copper that pose a threat to these wetlands. The latest large aggregation recorded at Pululos was in 2017 when 6,000 individuals were observed (Argentinean National Park Administration unpublished data) far from the almost 9,000 recorded in 1995 (Caziani & Derlindati 1996). For all the above reasons we suggest the species should remain in the “near threatened” category.
References:
Casagranda, E., Navarro, C., Grau, H.R. & Izquierdo, A.E. 2019. Interannual lake fluctuations in the Argentine Puna: relationships with its associated peatlands and climate change. Regional Environmental Change 19: 1737–1750.
Caziani, S. & Derlindati, E. 1996. Fulica cornuta en la Laguna de Pululos y otras cercanas, puna árida del noroeste de Argentina. Threatened Waterfowl Specialist Group News 9: 34–39.
Santamans, C.D., Cordoba, F.E., Franco, M.G., Vignoni, P. & Lupo, L.C. 2021. Hydro-climatological variability in Lagunas de Vilama System, Argentinean Altiplano-Puna Plateau, Southern Tropical Andes (22° S), and its response to large-scale climate forcings. Science of The Total Environment 767: 144926.
Many thanks to everyone who has contributed to this discussion. We greatly appreciate the time and effort invested in commenting. The window for consultation is now closed and we are unable to accept any more comments until 25 April 2025. We will now analyse and interpret the information, and we will post a preliminary decision on this species’ Red List category on this page on 25 April 2025, when discussions will re-open.
We thank all those who have contributed valuable information, which will be incorporated into the updated Red List assessment. Based on the responses received a more precautionary approach appears appropriate. While large concentrations have been reported occasionally, this species normally occurs at low densities and is described as rare and very local. The population size has previously thought to approach threatened thresholds, perhaps numbering between 10,000-20,000 mature individuals (Wetlands International 2025). Additionally considering suspected ongoing declines and the ongoing threats throughout the range, the population size may be moderately small, suspected here to fall within the band 5,000-25,000 mature individuals. Given this species is congregatory and highly dispersive, it is assumed to form a single subpopulation. Based on available information, our preliminary proposal for the 2025 Red List would be to list Horned Coot as Near Threatened under Criterion C2a(ii).
There is now a period for further comments until the final deadline on 4 May 2025, after which the recommended categorisations will be put forward to IUCN.
The final 2025 Red List categories will be published on the BirdLife and IUCN websites in October 2025, following further checking of information relevant to the assessments by both BirdLife and IUCN.
Many thanks to everyone who has contributed to this discussion. We greatly appreciate the time and effort invested in commenting. The window for consultation is now closed and we are unable to accept any more comments. We will analyse and interpret the information, and a final decision on this species’ Red List category will be posted on this page on 12 May 2025.
Recommended categorisation to be put forward to IUCN
The final categorisation for this species has not changed. Horned Coot is recommended to be listed as Near Threatened, approaching thresholds under Criterion C2a(ii).
Many thanks for everyone who contributed to the 2025.2 GTB Forum process. The final Red List categories will be published on the BirdLife and IUCN websites in October 2025, following further checking of information relevant to the assessments by both BirdLife and IUCN.
I live in Bolivia for the past ten years and am an active birdwatcher. Through both my work with Asociación Armonía and personal travels, I have visited many remote areas of the high Andes. Despite the extensive time spent surveying high-elevation lakes and wetlands, I have never encountered the Horned Coot. While this is anecdotal, I find it notable that even after visiting many sites where the species has historically been recorded, I have only observed Giant Coots, not Horned Coots.
In 2024, I participated in a Diademed Sandpiper-Plover (Phegornis mitchellii) census and witnessed widespread drying of high Andean bogs and lakes. This drying could be attributed to the severe El Niño-induced drought during the 2023–2024 season. However, it may also reflect longer-term changes caused by increasing lithium mining activity, which is expanding across several regions of the high Andes. In addition, overgrazing by large populations of domestic llamas may be degrading wetland quality and water availability.
I believe that the ecological changes occurring in remote Bolivian high Andean ecosystems are being significantly underestimated. The combined impacts of climate change, mining, and livestock pressure may be altering hydrological systems and reducing habitat quality for species like the Horned Coot. While I do not have quantitative data on Horned Coot population trends in Bolivia, the fact that I have not encountered the species at historically known sites over a decade of high-elevation fieldwork suggests a potential decline that requires further investigation.
We have been studying horned coots at the Vilama wetlands for a couple of years, where the largest aggregation has been recorded at Lake Pululos. We are currently working on two manuscripts focused on the species’ reproductive biology. Horned coots apparently do not reproduce every year and are highly nomadic and congregatory, relying strongly on couple of key lakes in Chile (Miscanti and Miñiques) and Argentina (Vilama). These seem to be strongholds particularly during dry years associated with ENSO events. Recent evidence also shows strong declines in lake area at Vilama in the last 30 years driven by reduced precipitation (Casagranda et al. 2019, Santamans et al. 2021). These changes can be accelerated by mining, particularly in Argentina, where there has been an explosion of mining projects on lithium and copper that pose a threat to these wetlands. The latest large aggregation recorded at Pululos was in 2017 when 6,000 individuals were observed (Argentinean National Park Administration unpublished data) far from the almost 9,000 recorded in 1995 (Caziani & Derlindati 1996). For all the above reasons we suggest the species should remain in the “near threatened” category.
References:
Casagranda, E., Navarro, C., Grau, H.R. & Izquierdo, A.E. 2019. Interannual lake fluctuations in the Argentine Puna: relationships with its associated peatlands and climate change. Regional Environmental Change 19: 1737–1750.
Caziani, S. & Derlindati, E. 1996. Fulica cornuta en la Laguna de Pululos y otras cercanas, puna árida del noroeste de Argentina. Threatened Waterfowl Specialist Group News 9: 34–39.
Santamans, C.D., Cordoba, F.E., Franco, M.G., Vignoni, P. & Lupo, L.C. 2021. Hydro-climatological variability in Lagunas de Vilama System, Argentinean Altiplano-Puna Plateau, Southern Tropical Andes (22° S), and its response to large-scale climate forcings. Science of The Total Environment 767: 144926.
Many thanks to everyone who has contributed to this discussion. We greatly appreciate the time and effort invested in commenting. The window for consultation is now closed and we are unable to accept any more comments until 25 April 2025. We will now analyse and interpret the information, and we will post a preliminary decision on this species’ Red List category on this page on 25 April 2025, when discussions will re-open.
Preliminary proposal
We thank all those who have contributed valuable information, which will be incorporated into the updated Red List assessment. Based on the responses received a more precautionary approach appears appropriate. While large concentrations have been reported occasionally, this species normally occurs at low densities and is described as rare and very local. The population size has previously thought to approach threatened thresholds, perhaps numbering between 10,000-20,000 mature individuals (Wetlands International 2025). Additionally considering suspected ongoing declines and the ongoing threats throughout the range, the population size may be moderately small, suspected here to fall within the band 5,000-25,000 mature individuals. Given this species is congregatory and highly dispersive, it is assumed to form a single subpopulation. Based on available information, our preliminary proposal for the 2025 Red List would be to list Horned Coot as Near Threatened under Criterion C2a(ii).
There is now a period for further comments until the final deadline on 4 May 2025, after which the recommended categorisations will be put forward to IUCN.
The final 2025 Red List categories will be published on the BirdLife and IUCN websites in October 2025, following further checking of information relevant to the assessments by both BirdLife and IUCN.
Many thanks to everyone who has contributed to this discussion. We greatly appreciate the time and effort invested in commenting. The window for consultation is now closed and we are unable to accept any more comments. We will analyse and interpret the information, and a final decision on this species’ Red List category will be posted on this page on 12 May 2025.
Recommended categorisation to be put forward to IUCN
The final categorisation for this species has not changed. Horned Coot is recommended to be listed as Near Threatened, approaching thresholds under Criterion C2a(ii).
Many thanks for everyone who contributed to the 2025.2 GTB Forum process. The final Red List categories will be published on the BirdLife and IUCN websites in October 2025, following further checking of information relevant to the assessments by both BirdLife and IUCN.