Habitat preferences of lesser rheas in Argentine Patagonia

Abstract

This work reports the first results of a 3-year study (1998 -2001) on habitat use and preferences by wild lesser rheas (Rhea pennata pennata) in the ecotone Monte-Patagonian steppe of Argentina. Ponds and four different habitat alternatives for lesser rheas were determined using satellite images and different structural vegetation characteristics: steppe, shrubland, shrub steppe, and mallines. Lesser rheas (adults, juveniles and chicks) used all habitats available to feed, although they showed preference for mallines, open areas that offer good visibility and abundant food resource. Rheas used shrub steppe and steppe for nesting, but they did not show preference for either habitat type. Nest site had a higher percentage of vegetation cover than control sites. Lesser rheas apparently preferred concealed sites for nesting since they offer protection from severe climate conditions and from predators. Our results suggest that habitat preference by lesser rheas counterbalances profitability of feeding to the corresponding cost of predation.

Abundance Estimates of the Lesser Rhea Rhea pennata pennata in the Argentine Patagonia: Conservation Implications

“…Considering habitat-related variables, the relative abundance of R. p. pennata was positively associated with GR and slight DLs. These results are coincident with the finding by Bellis et al (2005) who observed that lesser rheas preferred open habitats at a Monte-Patagonian Steppe ecotone in Río Negro, combining the availability of food and good visibility to detect predators. It has been suggested that the loss of habitat, together with poaching and egg collection are the main causes of population decline (Bellis et al, 1999;Funes et al, 2000;Barri et al, 2008).…”

“…Whereas, protected areas and remote sites, far from populated places, would favor the presence of lesser rheas. Also, we expect that open-grassland habitats will affect positively the abundance of lesser rheas as they provide forage and allow for early detection of predators (Bellis et al, 2005). At the same time, lesser-rheas could be negatively affected by habitat degradation due to desertification processes which are widespread across the arid Patagonia (del Valle et al, 1998).…”

Time–activity budget of greater rheas (Rhea americana, Aves) on a human-disturbed area: the role of habitat, time of the day, season and group size

“…In forested areas, vision is diminished by the understory vegetation, making these areas less attractive for the rheas (Bellis et al 2006;Codenotti and Alvarez 2000;Giordano et al 2008). On the other hand, pasture lands provide openness that favour vigilance and a rapid escape (Bellis et al 2004).…”

Density and abundance of Rhea pennata garleppi (Struthioniformes: Rheidae) in the Puna ecoregion of Argentina

“…While there was a record of an orphan egg in September 2012, no nest was found, despite the intensive search made inside the reserve. This drop in the number of individuals may be related to the species' nesting preferences, since individuals tend to select sites with high shrub cover, instead of pastures, which favors concealment and protection against predators and severe climate conditions (Bellis et al 2006;Barri et al 2009a). These sites are scarce in the study area, where shrub cover is only 16%, and pastures are 24%, whereas the remaining cover corresponds to bare soil (NV Marinero, unpublished data).…”

“…Specifically, the subspecies R. p. garleppi is distributed throughout the Puna ecoregion, where the low biomass production in the environment determines a lower carrying capacity. By contrast, the Argentine Patagonia, where R. p. pennata occurs, comprises a wider range of environments; the Monte and the Patagonia phytogeographic provinces, the Monte-Patagonia ecotone as well as 'mallines' (patchily distributed wetland areas), which provide habitat this ratite with important food resources (Oesterheld et al 1998;Bellis et al 2006;Guevara et al 2006;Bianchi and Bravo 2008).…”