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Title: Influence of natural factors and anthropogenic stressors on sperm whale foraging effort and success at high latitudes
Author: Isojunno, Saana
ISNI:       0000 0004 5364 7801
Awarding Body: University of St Andrews
Current Institution: University of St Andrews
Date of Award: 2015
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Behavioural responses can reveal important fitness trade-offs and ecological traps in evolutionarily novel contexts created by anthropogenic stimuli, and are of increasing conservation concern due to possible links to population-level impacts. This thesis illustrates the use of proxies for energy acquisition and expenditure within multivariate and state-based modelling approaches to quantify the relative time and energetic costs of behavioural disturbance for a deep-diving marine mammal (Physeter macrocephalus) in foraging grounds in Kaikoura Canyon (New Zealand) and near Lofoten Islands (Norway). A conceptual framework is first developed to identify and explore links between individual motivation, condition and external constraints to behavioural disturbance [Chapter 1]. The following chapters then use data from behavioural response studies (BRS) to: 1) derive biologically relevant metrics of behaviour [all chapters], 2) investigate effects of boat-based focal follows and tagging procedures [Chapters 2-3], and 3) relate responses to specific disturbance stimuli (distance, approach, noise) from whale-watching [Chapter 2], naval sonar and playback of presumed natural predator (killer whale Orcinus orca) sounds [Chapter 4]. A novel hidden state model was developed to estimate behavioural budgets of tagged sperm whales from multiple streams of biologging (DTAG) data [Chapter 3]. Sperm whales traded off time spent at foraging depths in a non-foraging and non-resting state in response to both tag boat presence, 1-2 kHz naval sonar (SPL 131-165 rms re 1μPa) and mammal-eating killer whale sound playbacks, indicating that parallel non-lethal costs were incurred in both anthropogenic disturbance and presumed antipredatory contexts. While behavioural responses were highly variable by individual, biologically informed state-based models appeared effective to control for variability in energy proxies across different functional contexts. These results and Chapter 5 “linking buzzes to prey” demonstrate that behavioural context is a signal that can aid understanding of how individual non-lethal disturbance responses can impact fitness.
Supervisor: Miller, Patrick Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: Physeter macrocephalus ; Cetacea ; Behavioural disturbance ; Behavioural response studies ; Whale-watching ; Naval sonar ; Risk-disturbance hypothesis ; Functional state ; State-switching model ; Time-series model ; QL737.C435I8 ; Sperm whale ; Cetacea ; Whales--Behavior ; Whale watching ; Sonar