Open Collections

Warham, Zac David

University of British Columbia

Marine mammals routinely travel vast distances across the oceans, but there is ongoing debate on how they manage these feats. The typical approach to investigating how animals navigate involves first identifying a specific cue or environmental correlate that may influence their decisions, and then looking for behavioural evidence to support this hypothesis. However, selecting a cue to investigate without a priori knowledge of an animal’s movements can be inefficient and lead to confirmation bias. Therefore, I set out to demonstrate how a meta-analysis that identifies movement patterns in previously collected data is a valuable tool to generate useful hypotheses in navigation research. I illustrate this process using telemetry data from the Antarctic fur seal (AFS; Arctocephalus gazella), a model species due to its extensive at-sea movement and the vast amount of existing publicly available location data spanning two decades. The data was pre-processed to split journeys into outbound and inbound transiting periods whilst discarding intermediary foraging behaviour. In total, reliable data was obtained from 86 individuals from Marion Island and 132 individuals from Bird Island for my analyses. I then deployed four different approaches to quantify potential patterns in their movement to ultimately determine how they navigate. Circular statistics identified consistent preference for island-specific dispersal direction during outbound legs from their home island, as well as similarities between outbound and inbound directions. Area analysis identified potential corridor usage during return legs suggesting regular travel routes that can be potentially used to identify environmental cues. Block design statistics showed the seals’ ability to gradually correct their heading during inbound legs to the island. However, I did not find any correlation between lunar fraction and the timing of the start of these return legs. This study with AFS also provides a demonstration of how clearly delineating patterns in movement will permit unbiased testing of environmental correlates to determine how marine mammals navigate. For marine mammals in general, this research illustrates the importance of meta-analyses as an efficient, informative approach to analysis decision-making.

Text

2024-08-19

Attribution-NonCommercial-NoDerivatives 4.0 International

http://hdl.handle.net/2429/88974

Oceans and Fisheries

University of British Columbia

UBCV

http://creativecommons.org/licenses/by-nc-nd/4.0/