|Scientific Name:||Podiceps gallardoi|
|Species Authority:||Rumboll, 1974|
|Red List Category & Criteria:||Critically Endangered A2bce+3bce+4bce ver 3.1|
|Reviewer/s:||Butchart, S. & Sharpe, C J|
|Contributor/s:||Casañas, H., Imberti, S., Mazar Barnett, J. & Roesler, I.|
This species has a very small and extremely rapidly declining population within a very small range. It is likely that birds may move between breeding sites on an annual basis but recent absences from former breeding sites are now believed to represent genuine declines. Therefore, the species has been uplisted to Critically Endangered.
Podiceps gallardoi breeds on a few basaltic lakes in the interior of Santa Cruz, extreme south-west Argentina; the only known wintering grounds are the río Coyle, río Gallegos and río Chico estuaries on the Atlantic coast of Santa Cruz (Johnson and Serret 1994, Imberti et al. 2004, Roesler et al. 2011b). It is apparently accidental in Magallanes, south Chile (Roesler et al. 2011b). The total population was estimated at 3,000-5,000 individuals in 1997 with half of these on Meseta de Strobel (O'Donnell and Fjeldså 1997). Counts on the wintering grounds suggested a decline of 40% over a seven year period (S. Imberti in litt. (2006), and surveys conducted in December 2006 and January 2009 that revisited key known breeding sites surveyed in 1987 (Lagunas del Sello, del Islote and Tolderia Grande) and 1998 (Encadenadas) also found sharp declines; numbers fell from 452 to 51 at Laguna del Sello, from 700 to 0 at Laguna del Islote, from 90 to 0 at Tolderia Grande (H. Casañas in litt. 2009) and from 198 to 0 at Lagunas Encadenadas (Konter 2008). The latest counts during the 2010-2011 breeding season found 535 individuals, which indicates a population decline of more than 80% over the last 26 years (Roesler et al. 2011b). While there is speculation that numbers fluctuate dramatically at breeding sites from year to year driven by movements rather than actual population fluctuations (Fjeldså 1986), overall declines detected on the wintering and breeding grounds appear to be real and rapid (Roesler et al. 2011b). Examination of photographs from the 1980s suggests that P. gallardoi was formerly the commonest waterbird on its core breeding grounds, the Buenos Aires, Strobel and San Martin plateaus; the 2009 surveys visited two of these areas and recorded the declines above as well as noting that a number of former breeding sites were completely dry.
|Range Map:||Click here to open the map viewer and explore range.|
|Population:||O'Donnell and Fjeldsa (1997) estimated the population to number 3,000-5,000 individuals. The minimum population size, based on simultaneous winter counts during 2010-2011, is 759 (Roesler et al. 2011b). Following recent and rapid declines, and new surveys, the latest estimate is 1,000-1,200 individuals, roughly equivalent to 660-800 mature individuals.|
|Habitat and Ecology:||During the breeding season, it inhabits basaltic lakes in the arid Patagonian steppes at elevations of 500-1,200 m(Chebez 1994); saline and bitter-salt lakes are used by non-breeding flocks and at least some birds wintering on the Argentine coast (Johnson and Serret 1994). Aquatic vegetation (mainly Myriophyllum elatinoides) on its breeding lakes is essential material for its floating nest and as habitat for several aquatic invertebrates that form its basic diet(Chebez 1994). During the first week after hatching, chicks are fed with aquatic beetles (Limnaea spp.) (Chebez 1994). It breeds in colonies of up to 130 pairs from October-March (Chebez 1994), but has an exceedingly low reproductive rate with an average of 0.2 young reared per adult per year (O'Donnell and Fjeldså 1997). However, while potential resources for breeding are apparently limited, the resources for adult survival appear to be plentiful and under natural circumstances adult mortality may be extremely low (O'Donnell and Fjeldså 1997). It occasionally establishes colonies in areas marginal to its main range (O'Donnell and Fjeldså 1997).|
|Major Threat(s):||The two principal threats to the species appear to be climate change and the introduction of salmon and trout to private lakes on the Strobel plateau (Imberti & Casañas 2010, S. Imberti in litt. 1999). Recently the introduction of trout has been correlated with a decline in breeding numbers at certain lakes (Konter 2008, S. Imberti in litt. 2006). Surveys in 2006, 2009 and 2010-2011 found a number of lakes completely dry and that water levels at known breeding sites were 2-3 m lower than in previous years (Konter 2008, Imberti & Casañas 2010, Roesler et al. 2011a). Anecdotal reports indicated reduced winter snowfall without a corresponding increase in precipitation at other times (Konter 2008). Excessive grazing by sheep (which causes erosion at lakeshores and limits the growth of emergent vegetation), predation by Kelp Gulls Larus dominicanus at some lakes, an inhospitable breeding climate and low breeding potential have been cited as threats (del Hoyo et al 1992, O'Donnell and Fjeldså 1997, Imberti & Casañas 2010), but the species's life history strategy is apparently well adapted to these conditions (Fjeldså 1986). In 2010-2011 an American Mink Neovison vison, a new arrival on the Buenos Aires plateau, killed more than half the adults in a breeding colony of two dozen nests (Roesler et al. 2011a). The population may be limited by the carrying capacity of rather few lakes with good nest vegetation (O'Donnell and Fjeldså 1997). Volcanic eruptions in the breeding area may have a negative short-term effect because of heavy ash fall, but a long-term positive effect on the productivity of the wetlands (O'Donnell and Fjeldså 1997). There is oil exploitation on the potential migration route to the Atlantic (S. Imberti in litt. 1999).|
Conservation Actions Underway
The site where the species was discovered in 1974, Laguna Los Escarchados, was declared a reserve in 1979 but is now known to hold only a marginal population (O'Donnell and Fjeldså 1997), and six individuals were recorded within Perito Moreno National Park, Argentina in 1992. Its key breeding lakes in the core of its range lack any kind of legal protection, but the population stronghold on Meseta de Strobel is afforded some protection from its remoteness and inaccessibility (del Hoyo et al 1992). Conservation Actions Proposed
Continue monitoring at key sites at intervals of a few years (O'Donnell and Fjeldså 1997). Survey upland and coastal sites to identify wintering and staging sites (O'Donnell and Fjeldså 1997). Write and implement a species recovery plan. Work with landowners to raise awareness of the impacts on Hooded Grebes of introducing salmonids to lakes, and identify lakes where salmonids could be introduced without negatively impacting Hooded Grebes. Study the species's ecology to understand population movements. Identify breeding sites. Gather empirical data on population size and trends. Clarify the threats to the species and the reasons behind recent declines.
Chebez, J. C. 1994. Los que se van: especies argentinas en peligro. Albatros, Buenos Aires.
del Hoyo, J.; Elliot, A.; Sargatal, J. 1992. Handbook of the Birds of the World, vol. 1: Ostrich to Ducks. Lynx Edicions, Barcelona, Spain.
Fjeldså, J. 1986. Feeding ecology and possible life history tactics of the Hooded Grebe Podiceps gallardoi. Ardea 74: 40-58.
Imberti, S., Sturzenbaum, S. and McNamara, M. 2004. Actualización de la distribución invernal de macá tobiano Podiceps gallardoi y notas sobre su problemática de conservación. Hornero 19: 83-89.
IUCN. 2012. IUCN Red List of Threatened Species (ver. 2012.1). Available at: http://www.iucnredlist.org. (Accessed: 19 June 2012).
Johnson, A.; Serret, A. 1994. Hooded Grebe wintering grounds discovered. Cotinga: 9.
Konter, A. 2008. Decline in the population of Hooded Grebe Podiceps gallardoi?. Cotinga: 135-138.
O'Donnell, C.; Fjeldsa, J. 1997. Grebes: a global action plan for their conservation.
Roesler, I.; Casañas, H.; Imberti, S. 2011. Final countdown for the Hooded Grebe? Neotropical Birding 9: 3-7.
Roesler, I.; Imberti, S.; Casañas, H.; Reboreda, J. C. 2011. Proposal for upgrading the Hooded Grebe (Podiceps gallardoi) to Critically Endangered.
Roesler, I.; Imberti, S.; Casañas, H.; Volpe, N. 2012. A new threat for the globally Endangered Hooded Grebe (Podiceps gallardoi): the American mink Neovison vison. Bird Conservation International.
|Citation:||BirdLife International 2012. Podiceps gallardoi. In: IUCN 2012. IUCN Red List of Threatened Species. Version 2012.2. <www.iucnredlist.org>. Downloaded on 23 May 2013.|
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