INVESTIGADORES
QUINTANA Flavio Roberto
congresos y reuniones científicas
Título:
Better budgets: measurement of foraging effort reveals Imperial cormorants select foraging currency with depth
Autor/es:
SHEPARD, E.; WILSON, R.; QUINTANA, F.; GOMEZ LAICH, A.
Lugar:
Hakodate, Hokkaido, Japan
Reunión:
Congreso; 36th Annual Meeting of the Pacific Seabird Group; 2009
Resumen:
<!--
/* Font Definitions */
@font-face
{font-family:Calibri;
panose-1:2 15 5 2 2 2 4 3 2 4;
mso-font-charset:0;
mso-generic-font-family:swiss;
mso-font-pitch:variable;
mso-font-signature:-520092929 1073786111 9 0 415 0;}
/* Style Definitions */
p.MsoNormal, li.MsoNormal, div.MsoNormal
{mso-style-parent:"";
margin:0cm;
margin-bottom:.0001pt;
text-align:justify;
mso-pagination:widow-orphan;
font-size:11.0pt;
font-family:Calibri;
mso-fareast-font-family:"Times New Roman";
mso-bidi-font-family:"Times New Roman";
mso-fareast-language:EN-US;}
p
{mso-style-noshow:yes;
mso-margin-top-alt:auto;
margin-right:0cm;
mso-margin-bottom-alt:auto;
margin-left:0cm;
mso-pagination:widow-orphan;
font-size:12.0pt;
font-family:"Times New Roman";
mso-fareast-font-family:Calibri;}
@page Section1
{size:612.0pt 792.0pt;
margin:70.85pt 3.0cm 70.85pt 3.0cm;
mso-header-margin:36.0pt;
mso-footer-margin:36.0pt;
mso-paper-source:0;}
div.Section1
{page:Section1;}
-->
Time and energy are fundamental currencies
in the foraging ecology of diving birds. Birds may maximise their foraging
success in relation to either the time or energy spent, and can alter the
currency by varying the allocation of time or energy to different phases of the
dive (e.g. in travel to and from the foraging depth, prey searching, prey
handling). While time budgets have been widely used to consider the allocation
of time to the different dive phases, energy costs within dives have not been
measured directly, even though there is evidence that they vary according to
circumstance. Overall dynamic body acceleration (ODBA), which correlates
linearly with energy expenditure in a number of species, was used to estimate
foraging costs in male Imperial cormorants (Phalacrocorax atriceps) using
animal-attached loggers. The duration of all dive phases increased linearly
with depth, whereas overall effort per dive increased curvilinearly. Derived
time and energy costs were used to model the dive behaviour that would optimise
bottom time (where prey are encountered in this species) as a function of (a)
dive-cycle duration (bottom time per unit time, bTPUT) and (b) dive effort
(bottom time per unit effort, bTPUE). Birds appeared to maximise bTPUE at
depths > 25 m, but diving behaviour was more consistent with a strategy to
optimise bTPUT at shallow depths. This was interpreted as a response to
depth-related changes in prey availability, as greater depths are associated
with more profitable prey (measurable by head-mounted transducers e.g. IMASEN and
acceleration), which, when located, may free birds from foraging under time
constraints.
