DOI: 10.5061/dryad.n820k
title: Data from: Sex differences in risk perception in deep-diving bottlenose dolphins leads to decreased foraging efficiency when exposed to human disturbance

description: 1. Individuals make behavioural decisions by weighing potential advantages
 and costs (e.g. increased food intake vs. increased risk of predation).
 When animals change their activities in response to a perceived threat,
 their energetic input may decline. Marine ecotourism, including whale and
 dolphin watching, is growing globally and cetaceans perceive interactions
 with tour vessels as a form of risk. Observable behavioural changes need
 to be linked to bioenergetic effects to determine the potential population
 consequences of this disturbance. 2. We developed a theoretical optimal
 dive model for bottlenose dolphins under three potential types of
 perceived risk resulting from human interactions at the surface
 (decreasing instantaneous risk, increasing instantaneous risk and no
 risk). We compared the predictions of these theoretical models to observed
 dive cycles of foraging male and female dolphins in the presence and
 absence of tour vessels. We used mixture models to classify dive types and
 mixed effects models to analyse changes in the interbreath interval of
 surface and bottom dives and the frequency of estimated bottom dives. 3.
 Males significantly increased bottom time and performed fewer bottom dives
 when boats were present, matching predictions of our theoretical model for
 perceived decreasing instantaneous risk. In contrast, females
 significantly decreased bottom times and increased the frequency of bottom
 dives, matching predictions from the model for perceived increasing
 instantaneous risk. Therefore, our empirical results suggest differences
 in the perception of risk between sexes. 4. Synthesis and applications. By
 comparing theoretical predictions with observed dive data, our study
 suggests that boat interactions during foraging can cause decreased net
 energy gain over a foraging bout for both sexes, with females being more
 impacted. The population under study is currently listed as critically
 endangered. Understanding whether these predicted energetic impacts affect
 an individual's vital rates will provide a link to the
 population-level consequences of this disturbance. Previous analytical
 approaches have failed to capture the costs associated with disturbance
 during foraging, leading to management recommendations that only protect
 animals from increased energetic expenditure. We suggest that the current
 management scheme should be revised to include foraging areas in order to
 secure the energy intake of animals.
description: focal follow data used
 to test theoretical predictionsindividual focal follow
 of dolphin breathing in Doubtful Sound, Fiordland, New Zealand collected
 in 2000-2002. See Symons et al. for further methodological details. This
 data was used to carry out analyses in that paper to test changes in
 inter-breath interval (IBI) ("divetime") for different types of
 IBI ("divetype") depending on the presence of boats
 ("simpleboat") of individual bottlenose dolphins
 ("individual") for which the gender was known
 ("sex").Symons_data.csv