Wednesday, August 8, 2007: 1:50 PM
Blrm Salon V, San Jose Marriott
A total of 25 macaroni penguins were tagged at Bird Island , South Georgia between November and March during the 2000-2001 austral summer. Each bird was fitted with a Time Depth Recorder (TDR) that recorded depth and time every 2 seconds until recapture. These data were analysed as a time series and as a record of individual dives. Time series analysis showed significant differences in autocorrelation patterns between individuals and between stages in the reproductive cycle.
The data were summarised as dives with associated variables using our own software. Autocorrelation analysis showed that up to 60 successive dives were correlated. Attributes of these dives (maximum depth, duration and foraging intensity at depth) were analysed for a range of explanatory variables such as stage, time of day and prior surface interval. There were consistent differences between stages, mostly due to penguins in the Incubation and Premoult stages diving at night, while Brood Guard and Creche individuals restrict their diving to daylight hours.
These data were used to devise a new method of identifying bouts, and investigate the hypothesis of whether penguins dive in clustered behaviour. In light of our results, we call into question the validity of the traditional method of characterising bouts in diving animals, and we develop a new method which makes far fewer assumptions.
The data were summarised as dives with associated variables using our own software. Autocorrelation analysis showed that up to 60 successive dives were correlated. Attributes of these dives (maximum depth, duration and foraging intensity at depth) were analysed for a range of explanatory variables such as stage, time of day and prior surface interval. There were consistent differences between stages, mostly due to penguins in the Incubation and Premoult stages diving at night, while Brood Guard and Creche individuals restrict their diving to daylight hours.
These data were used to devise a new method of identifying bouts, and investigate the hypothesis of whether penguins dive in clustered behaviour. In light of our results, we call into question the validity of the traditional method of characterising bouts in diving animals, and we develop a new method which makes far fewer assumptions.
