INVESTIGADORES
RAYA REY Andrea Nelida
congresos y reuniones científicas
Título:
New insights into the foraging behaviour and habitat of Rockhopper Penguins at Staten Island.
Autor/es:
A RAYA REY; N ROSCIANO; K PÜTZ; B LÜTHI
Reunión:
Congreso; 8 International Penguin Conference; 2013
Resumen:
Understanding
the foraging behaviour and foraging habitat of species is crucial to various
applications in ecology and conservation. The aim of this study was to analyze
the foraging habitat characteristics of female rockhopper penguins during
brooding at Staten Island using GPS and time-depth data, and to ascertain if
different foraging strategies persist in the population. Using MaxEnt
modelling, we applied ecological niche models to establish the oceanographic
variables influencing the utilized brooding habitat. The most important
oceanographic parameters predicting the at-sea distribution of the birds
studied were the proximity of the shelf break and the sub Antarctic front (=
SAF). A cluster observation analysis revealed two different foraging
strategies: The first one was determined by bathymetry, sea surface temperature
and the SAF (= coastal strategy), whereas the most important variables for the
second group were the SAF, the shelf break and chlorophyll values (= pelagic
strategy). Dive characteristics differed slightly between the two groups.
Bottom time, number of wiggles, mean and maximum dive depth were higher in
pelagic compared with coastal penguins. Stable isotope analysis of whole blood
samples showed contrasting values for δ13C (-21.6 ± 0.5, -22.5 ±
0.4, for coastal and pelagic birds respectively) but no differences for δ15N
(9.9 ± 0.4, 9.3 ± 0.4, respectively). The carbon value for coastal birds was
higher than expected. As whole blood sampling integrated both, brooding
and the incubation trip of the females,
a potential explanation might be that coastal birds used more than one foraging
strategy at a time (pelagic and coastal), or used a pelagic strategy during
incubation and a coastal strategy while brooding. Given the known distribution
of females during incubation from previous studies, the second explanation
appears more plausible. The combination of these two strategies in the
population during brooding could be advantageous as birds were reducing spatial
overlapping while feeding within the same trophic level. Finally, this study highlights the importance
of the SAF for rockhopper penguins, an oceanographic feature susceptible to
changes in location following global warming and
subsequent implications for conservation measures.