Hooded Grebe Podiceps gallardoi

  • Order: Podicipediformes
  • Family: Podicipedidae
  • Monotypic
  • Authors: S. Imberti, H. Casañas, and Ignacio Roesler
Sections

Demography and Populations

After its discovery in 1974, it was estimated that the population of the Hooded Grege was a relic confined to Escarchados lagoon, numbering less than 150 individuals. Fundación Vida Silvestre Argentina dedicated its efforts towards studying this species, with discouraging results regarding its general condition. After a few nesting failures it was decided to search for other populations in nearby lakes. These searches extended over most of the plateaus in Santa Cruz province, mainly due to the efforts of the late Andrés Johnson (1982, 1985, 1986, 1994, 1997, Beltrán et al. 1987). Estimates after these efforts pointed to a population of around 3000 to 5000 (Beltrán et al. 1987, Fjeldså 1986b). Its winter habitat was unknown until part of the population was found in 1994 (Johnson and Serret) but the searches did not resume until the period 1999 - 2004, when Imberti (et al. 2004) were able to do more work on its wintering grounds. They reported surveying the Chilean Fiords and the southern part of Santa Cruz where some new sites for the species were discovered. However, the numbers they found suggested that the grebe’s population might be declining. Clearly, summer information was needed and accordingly, Asociación Ambiente Sur organized expeditions to the plateau in January and March 2009. The four plateaus (Strobel, Buenos Aires, Siberia and Viedma) identified during the 1980s as having the large majority of breeding grebes were visited. Over 50 lakes and lagoons, which included the six key water bodies thought to host 40% of the total population in the 1980’s (Johnson 1997), were surveyed. Of the six key lakes from the 1980s, three were entirely devoid of grebes and the others had far fewer grebes than during that decade. In the 1980s, the total mean number of adults found on these lakes was 1,832; the recent surveys found only 117 individuals. The equivalent figures for nests were 581 and zero. These findings were sufficient evidence for BirdLife International, in its 2009 edition of the IUCN Red List, to uplist the Hooded Grebe by two whole categories of threat due to a possible decline of 40% (see Conservation Status).

Subsequent field work in the 2010/11 summers produced a more extensive coverage of the plateaus with over 250 lakes visited and many more were found dry. Due to this factor, the discovery of the mink as a serious problem and the rest of the currently known threaths, the total population of the grebe may have declined as much as 60% and it is estimated to be under 1200 individuals.

Recommended Citation

Imberti, S., H. Casañas, and I. Roesler (2009). Hooded Grebe (Podiceps gallardoi), version 1.0. In Neotropical Birds Online (T. S. Schulenberg, Editor). Cornell Lab of Ornithology, Ithaca, NY, USA. https://doi.org/10.2173/nb.hoogre1.01