Conservation of the Hooded Grebe

(Podiceps gallardoi)

by Ignacio Roesler

The grebes (Order PODICIPEDIFORMES) are a cosmopolitan group that inhabits aquatic environments. This group, composed by 22 species, is one of the most threatened species in the world, together with the parrots and albatrosses: Three species have become extinct over the past years, five are globally threatened and one was recently classified as near threatened (Birdlife International).

New Zealand Grebe (Poliocephalus rufopectus): vulnerable; Madagascar Grebe (Tachybaptus pelzelnii): vulnerable; Titicaca Grebe (Rollandia microptera): endangered; Junin Grebe (Podiceps taczanowskii): critically endangered; Hooded Grebe (Podiceps gallardoi): critically endangered; Colombian Grebe (Podiceps andinus): extinct in 1977; Atitlan Grebe (Podilymbus gigas): extinct in 1989; Alaotra Grebe (Tachybaptus rufolavatus): extinct in 2010.

The Hooded Grebe (Podiceps gallardoi) was discovered to science as recently as in 1974, by the famous Argentine naturalist Mauricio Rumboll at Escarchados Lake, no more than 62mi (100km) east of the Perito Moreno Glacier. It is an endemic breeder of Argentina with a local distribution in western Santa Cruz province (southern Patagonia). During the breeding season, its distribution extends over an area of high plateaus, east of the Andes, and during the winter, they are found in estuaries along the Atlantic coast (in the same province). Some individuals are seen in the lakes located near Punta Arenas and in the Chilean side of Tierra del Fuego, but still, no one knows where they come from (most likely, from the nearby plateau Vizcachas, close to El Calafate).
The population of this specie was estimated at 3000-5000 individuals in the 80’s. Nevertheless, during the past five breeding seasons (2009-2014), we counted a population of no more than 800 adult individuals. Thus, we observe that more than 80% of the population declined in only 3 generations. The threats proposed are: acidification of lakes by desertification; predation of nests and chicks by the Kelp Gull (Larus dominicanus); lake alteration and competition for food by exotic salmonids (mainly Rainbow trout), introduced for commercial purposes; destruction of nests by winds; and volcanic activity. During the 2010/11 season, we detected a new and dangerous threat, the American Mink (Neovison vison). Only one individual of these aggressive exotic predators destroyed a colony with 21 nests and killed 33 adult grebes.

A gaunt scene: In early 2011, just one American Mink (exotic species) killed 33 breeding adult Hooded Grebes on the Buenos Aires plateau, Santa Cruz, Argentina (I. Roesler).

In the last five years, Aves Argentinas and Ambiente Sur, together with LEyCA (Lab de Ecología y Comportamiento Animal IEGEBA-FCEN, UBA) have advanced locally, nationally and internationally in conducting outreach and educational activities about the situation of the Hooded Grebe (e.g., reports in various national and international media; popular science articles; etc.). The presentation of the documentary “The Twilight of the Hooded Grebe” achieved national and international impact and had the support of two Academy Award winners: Ricardo Darín and Gustavo Santaolalla.

Hooded Grebe was elevated to the category of “Critically Endangered" in 2012. It is of utmost importance to continue studying their reproductive biology and life cycle. Although aspects of their behavioral ecology have been described, the main factors affecting their reproduction have not yet been thoroughly analyzed.


The study area is in the province of Santa Cruz, Argentina. This province is located at the southern tip of the continental South America (southern Patagonia), between the Andes on the west and the Atlantic Ocean on the east. Parallel and east to the Andes, there are several basaltic plateaus or mesetas. The main plateaus from north to south are: 'Buenos Aires', 'Asador', 'Strobel', 'Ventana', 'Moro', 'Siberia', 'Viedma' and 'Vizcachas', and they go from 47°S to 51°S, with elevations varying between 1640 ft (500m) and 4,921 ft (1500m) meters above sea level. These plateau areas range from 30 to 2900 km2 and hold endorheic volcanic and non-volcanic lakes which accumulate water from precipitation and snow melts during winter; their number varies greatly among plateaus. The physicochemical characteristics of water in these lakes are mainly determined by the composition of underlying sediments, which result in a wide diversity of limnological characteristics. Many of these lakes, naturally devoid of fish, are covered by dense macrophyte stands of water milfoil, Myriophillum quitense and maintain a rich aquatic biodiversity. Due to the fact that many of these lakes have exceptionally large numbers of congregatory species and hold significant numbers of globally threatened Hooded Grebes, some plateaus (i.e., 'Buenos Aires', 'Asador' and 'Strobel') are considered "Important Bird Areas" or IBAs.
We have been working non-stop in the area since the breeding seasons of 2008-2009 to 2013-2014. During this period, we visited almost 400 big lakes (and hundreds of temporary ponds) located at the main plateaus of Santa Cruz province (see Map). The survey conducted during the breeding season 2008-2009 was exploratory and included a reduced number of lakes (n = 38), while the surveys conducted during the breeding seasons 2009-2010 to 2013-2014 were more exhaustive and included up to 275 lakes in a single season. During these surveys, we visited most of the lakes in which the presence of Hooded Grebes had been previously reported.
In each lake, we conducted censuses of Hooded Grebes and other birds. People involved in all the censuses had previous experience identifying waterfowl species at Patagonian lakes. We made the bird identification using 15-60x spotting scopes and 10x42 binoculars. Counts were conducted independently by two to four observers and each observer performed at least two consecutive counts. We considered that the number of Hooded Grebes in a given lake was the most frequent value of these counts. When weather conditions were not appropriate (i.e. strong winds) we doubled the number of counts. We considered that a pair was nesting only if we observed eggs in the nest, since some individuals can build the nest structure and abandon it before laying the egg. Lakes within the same plateau were visited serially in relatively short periods of time (range 1-3 days) to minimize the risk of double-counting birds which could have moved among lakes. We did not include a few counts conducted earlier in the breeding season (mid-late October and November) because Hooded Grebes at first tend to aggregate in a few lakes from which they later move to those others where they actually attempt to breed. The inclusion of these early counts could have led us to overestimate Hooded Grebe’s population.

Conservation Actions

We have been supporting Aves Argentinas and Ambiente Sur with the management plan that they are developing since 2010. The long-term conservation plan to preserve the Hooded Grebe was conceived during the first “Hooded Grebe Project’s Workshop” developed in Aves Argentinas/AOP’s offices during 2009. The plan seeks to create a “road map” that helps to keep the scope focused on the most needed actions. But the increase on the knowledge of the species and its threats made us change the original plan a little. One of the main changes was the actions that are currently undertaken to control its most furious predator, the American mink. Together with Dr. Laura Fasola (CADIC-CONICET), we had developed a control plan which was already implemented on the Buenos Aires Lake plateau. To date, it is one of the most extensive and successful plans carried out in Argentina. In this plan, the ANP (Spanish acronym for Protected Natural Areas) also took an important role and nowadays, we are considering expanding it to other protected areas.
But probably one of the major actions that we had the honour to participate in was to impulse on the creation of the Patagonia National Park. This new national park protects nearly the 50% of the Hooded Grebe population.
Habitat restoration by catching Rainbow trout is one of the main goals for the next season (2014/15) and it will be probably a highlight of conservation in Argentina. For this work with exotics salmonids, we collaborated (and we still collaborate) with Dr. Julio Lancelotti (ECOPAT-CENPAT-CONICET) and with Dr. Irina Izaguirre and her team (IEGEBA-CONICET). Management programs to diminish Kelp Gull reproduction on the plateaus had been also undertaken.
Lastly, but not least important, since 2010, we have been supporting an extensive educational programme at different levels, in several provinces, but most importantly in Santa Cruz.

Related publications


Roesler I. The status of the Hooded Grebe (Podiceps gallardoi) in Chile. Ornitologia Neotropical 26: 255-263 (2016).

Roesler I, Imberti S, Casañas HE, Hernández PM, Klavins JM and Pagano LG. Noteworthy records and natural history comments on rare and threatened bird species from Santa Cruz province, Patagonia, Argentina. Revista Brasileira de Ornitologia 22(2): 189-200 (2014).

Roesler I, Imberti S, Casañas H and Volpe NA. A new threat for the globally Endangered Hooded Grebe Podiceps gallardoi: the American mink Neovison vison. Bird Conservation International 22: 383-388 (2012).

Roesler I, Imberti S, Casañas H, Mahler B and Reboreda JC. Hooded Grebe Podiceps gallardoi population decreased by eighty per cent in the last twenty-five years. Bird Conservation International 22: 371-382 (2012).

Casañas H, Roesler I, Imberti S and Hernández P. Esperanza Tobiana. Aves Argentinas N&C (June 2012).

Roesler I, Casañas H and Imberti S. Final countdown for the Hooded Grebe?. Neotropical Birding 9: 3-7 (2011).

Casañas H, Imberti S and Roesler I. Hooded Grebe: the next member of the "extinct grebes club"?. World Birdwatch, BirdLife international (September 2011).

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