INVESTIGADORES
ZARCO Agustin
congresos y reuniones científicas
Título:
DEMOGRAPHY OF GRANIVOROUS BIRDS IN THE CENTRAL MONTE DESERT AND ITS ASSOCIATION WITH LOCAL FOOD ABUNDANCE
Autor/es:
SAGARIO MC; CUETO VR; LOPEZ DE CASENAVE J; A ZARCO
Reunión:
Congreso; IX Congreso de Ornitología Neotropical y VIII Congreso Peruano de Ornitología.; 2011
Resumen:
Demographic studies are crucial to fully understand the causes of variation in the
abundance of populations, which may be related to environmental conditions and resource
availability. We evaluated the association of the abundance of four granivorous bird
species with seed production, arthropod abundance and precipitation in the Ñacuñán
Biosphere Reserve (central Monte desert, Argentina), through the analysis of productivity
and survival using mark-capture-recapture techniques between 2004-2010. During the wet
year of high seed production (good year), adult abundance and survival did not differ from
average years, but productivity was unusually high. During the year of low seed and
arthropod abundance (bad year), adult abundance and survival during the winter were
extremely low, but neither abundance nor productivity differed from average years during
the breeding season. Juvenile recapture rate was low and there was no association
between productivity and adult abundance during the following season. Adult abundance
was variable and survival was constant during average and good years, and we did not
find lower adult abundance following the year of the lowest survival. We conclude that year
to year fluctuations of granivore abundance do not usually come from short-term changes
in survival or local productivity, but from individual movements to and from the study area
instead. However, resource availability affects local abundance during exceptionally good
or bad years, through increased productivity and decreased survival, respectively.
Therefore, we suggest that granivorous birds dynamics in the central Monte desert usually
reflects bird movements at a regional scale, although could be locally controlled by
sporadic events of limitation during bad years (crunch periods) and by opportunistic
responses during exceptionally good years