Obtaining morphometric data on free-ranging marine megafauna is difficult, as traditional methods rely on post-mortem or live-capture techniques. We linked stereo-laser photogrammetry with long-term demographic data to compare length-at-age (LaA) growth curves of two well-studied populations of Indo-Pacific bottlenose dolphins ( Tursiops aduncus ) in south-western (SW) and Shark Bay (SB), mid-western Australia. First, we determined the relationship between total length (TL) and blowhole-to-dorsal fin (BH-DF) length from post-mortem subjects (R 2 = 0.99, n = 12). We then predicted TL from laser-derived BH-DF measurements of 129 and 74 known-age individuals in SW and SB, respectively. Richards growth models best described our LaA data. While birth length (103–110 cm) was similar between study regions, TL estimates at 1, 3, 12, and 25 years differed significantly (p < 0.001). Asymptotic length of adult males (SW = 246 cm, SB = 201 cm) and females (SW = 244 cm, SB = 200 cm) also differed significantly. Morphotypic variations likely reflect regional adaptations to local water temperatures, with the temperate SW having cooler waters than sub-tropical SB. We demonstrate the effectiveness of a non-invasive technique to understand ecological, demographic and life-history characteristics of long-lived marine megafauna, which are critical parameters for informing conservation and management actions.
Food-provisioning of wildlife can facilitate reliable up-close encounters desirable by tourists and, consequently, tour operators. Food-provisioning can alter the natural behavior of an animal, encouraging adverse behavior (e.g. begging for food handouts), and affect the reproductive success and the viability of a population. Studies linking food-provisioning to reproductive success are limited due to the lack of long-term datasets available, especially for long-lived species such as marine mammals. In Bunbury, Western Australia, a state-licensed food-provisioning program offers fish handouts to a limited number of free-ranging bottlenose dolphins (Tursiops aduncus). Coupled with long-term historical data, this small (<200 individuals), resident dolphin population has been extensively studied for over ten years, offering an opportunity to examine the effect of food-provisioning on the reproductive success of females (ntotal = 63; nprovisioned females = 8). Female reproductive success was estimated as the number of weaned calves produced per reproductive years and calf survival at year one and three years old was investigated. The mean reproductive success of provisioned and non-provisioned females was compared using Bayes factor. We also used generalized linear models (GLMs) to examine female reproductive success in relation to the occurrence of food-provisioning, begging behavior and location (within the study area). Furthermore, we examined the influence of these variables and birth order and climatic fluctuations (e.g. El Niño Southern Oscillation) on calf survival. Bayes factor analyses (Bayes factor = 6.12) and results from the best fitting GLMs showed that female reproductive success and calf survival were negatively influenced by food-provisioning. The negative effects of food-provisioning, although only affecting a small proportion of the adult females’ population (13.2%), are of concern, especially given previous work showing that this population is declining.
Auditory thresholds were determined by a modified method of limits under 10 intensities of light (patterned or homogeneous). An analysis of variance of the data showed significant results for intensity conditions, personality type and the interaction of these parameters. Auditory sensitivity increased under weak, and decreased under strong, intensities of light in introverts. It increased under all intensities in extraverts, with greater increase at greater intensities, and increased under weak and medium intensities in ambiverts. The EPI E, but not N, scale scores and sensitivity increases correlated positively, at medium and strong intensities of light. 267-273,London : University of London Press. 531-568.Psychol. Bull. 73, 1Gl-199. (In Japanese.) Psychol. 81, 365-369. 659-698. auditory sensitivity. (Unpublished manuscript.) tion, University of Aberdeen.) dissertation, University of Reading.) 26-37. (In Japanese.) h d u n g e n insbesondere a d den Gesichtssinn. Arch. ges. Physiol. 30, 129-175.
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.
Ten experiments are reported. In each the effect of a heteromodal stimulus on visual sensitivity is investigated. With one exception all the stimuli produced a small increase in visual sensitivity. A number of possible explanations of intersensory facilitation are considered.
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