INVESTIGADORES
BELLIS Laura Marisa
artículos
Título:
Abundance and spatial distribution of Greater Rhea Rhea americana in two sites of the pampas grasslands with different land use.
Autor/es:
GIORDANO P. F., BELLIS, L. M., J. L. NAVARRO AND M. B. MARTELLA
Revista:
BIRD CONSERVATION INTERNATIONAL
Editorial:
CAMBRIDGE UNIV PRESS
Referencias:
Año: 2008 vol. 18 p. 63 - 70
ISSN:
0959-2709
Resumen:
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In Argentina
the original landscape structure of the pampas grasslands has changed rapidly
due to intensified and specialized agricultural practices. The conversion of
grasslands into croplands has been suggested as a threat to Greater Rhea Rhea
americanapopulations. The main goals of this study were to estimate the
abundance of Greater Rheas and to analyse the species spatial distribution at
two sites of the pampas region with different land use: agro-ecosystem and grassland.
The former was mainly devoted to crop production whereas the latter was mostly
used for livestock grazing. Data were collected through 14 aerial surveys from 1998
to 2001, and in 2004. Each survey consisted of six strip-transects per site,
spaced at regular intervals. The total area surveyed represented 4% of each
study site (113 km2 in the grassland and 95 km2 in the agro-ecosystem). Greater Rhea density (¡SE) was
significantly higher in the grassland (from 0.22 ¡0.11 to 0.86 ¡ 0.24 ind. km22)
than in the agro-ecosystem (from 0.05 ¡ 0.05 to 0.12 ¡0.08 ind. km22). Greater
Rheas occupied 51% of the study area in the grassland but less than 5% in the
agro-ecosystem. They showed a wide and uniform spatial distribution in the
former area, whereas in the latter individuals occurred in small and isolated
clusters. These results raise concern about the future of the species because,
over recent years, land has been increasingly used for crop production. Hence,
if the current rate of change in land use continues, the conservation status of
this species will be seriously affected.
