The emergent properties of a dolphin social network Lusseau, David
Proceedings - Royal Society. Biological sciences/Proceedings - Royal Society. Biological Sciences,
11/2003, Letnik:
270, Številka:
Suppl 2
Journal Article
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Many complex networks, including human societies, the Internet, the World Wide Web and power grids, have surprising properties that allow vertices (individuals, nodes, Web pages, etc.) to be in close ...contact and information to be transferred quickly between them. Nothing is known of the emerging properties of animal societies, but it would be expected that similar trends would emerge from the topology of animal social networks. Despite its small size (64 individuals), the Doubtful Sound community of bottlenose dolphins has the same characteristics. The connectivity of individuals follows a complex distribution that has a scale-free power-law distribution for large k. In addition, the ability for two individuals to be in contact is unaffected by the random removal of individuals. The removal of individuals with many links to others does affect the length of the 'information' path between two individuals, but, unlike other scale-free networks, it does not fragment the cohesion of the social network. These self-organizing phenomena allow the network to remain united, even in the case of catastrophic death events.
Nature-based tourism activities have been developing over the last decade, but it is still difficult to manage these activities sustainably. This sector is increasingly focusing on whales and ...dolphins in coastal communities, but the exact effects of these tourism activities are unclear. Markov chain modeling may help researchers assess the effects of tourism activities on the behavioral budget of small cetaceans. Matrix models have been used widely in population ecology to provide successful management guidelines. From June 2000 to August 2001,I collected information on the behavioral state of bottlenose dolphin (Tursiops spp.) schools from a population residing in Doubtful Sound, Fiordland, New Zealand. In addition, I recorded the occurrence of boat and dolphin interactions. I then calculated the transition probabilities of passing from one behavior to another by using a first-order, time-discrete Markov chain model. Behavioral transitions during which a boat-dolphin interaction occurred were compiled in an "impact" chain. All other transitions were tallied in a control chain. I then quantified the effect of boat-dolphin interactions during behavioral transitions by comparing the behavioral transition probabilities of both chains. Socializing and resting behaviors were disrupted by interactions with boats to a level that raises concern. Both the duration of bouts and the total amount of time spent in both these behavioral states were substantially decreased. Dolphins were significantly more likely to be traveling after an interaction with a boat. However, the overall behavioral budget of the population was not significantly affected. Therefore, the bottlenose dolphin population seems to be able to sustain the present level of boat interactions because of its low intensity. More effort is needed to develop prognosis analyses in order to understand how the effect of boat interactions on dolphins changes with variations in intensity.
Big data offer a great opportunity for nature-based recreation (NbR) mapping and evaluation. However, it is important to determine when and how it is appropriate to use this resource. We used ...Scotland as a case study to validate the use of data from Flickr as an indicator of NbR on a national scale and at several regional spatial and temporal resolutions. We compared Flickr photographs to visitor statistics in the Cairngorms National Park (CNP) and determined whether temporal variability in photo counts could be explained by known annual estimates of CNP visitor numbers. We then used a unique recent national survey of nature recreation in Scotland to determine whether the spatial distribution of Flickr photos could be explained by known spatial variability in nature use. Following this validation work, we used Flickr data to identify hotspots of wildlife watching in Scotland and investigated how they changed between 2005 and 2015. We found that spatial and temporal patterns in Flickr count are explained by measures of visitation obtained through surveys and that this relationship is reliable down to a 10 Km scale resolution. Our findings have implications for planning and management of NbR as they suggest that photographs uploaded on Flickr reflect patterns of NbR at spatial and temporal scales that are relevant for ecosystem management.
The need for managing non‐lethal effects on wildlife is becoming increasingly important as global human–wildlife interactions are now more frequent and more diverse. We developed a mechanistic model ...for minke whales (Balaenoptera acutorostrata) to measure the effects of behavioral disturbances caused by whalewatching activities on fetal growth. The model illustrates the pathway through which behaviorally mediated effects of anthropogenic disturbance might influence female reproductive success in an iteroparous capital breeding mammal. We found that although the behavioral disruptions caused by whalewatching interactions were substantial, the cumulative exposure of individuals to whalewatching boats was low, resulting in an effect on fetal growth no different from natural variability. This highlights the importance of considering all aspects of disturbance when evaluating effects of human disturbance on wildlife. Our mechanistic model can also be used to simulate different management scenarios to predict the long‐term consequence of disturbance on vital rates, to help inform management decisions.
Reports and discusses the result of a study to examine the role of dyadic and group interactions in the association patterns of male bottlenose dolphins in Doubtful Sound, New Zealand. Source: ...National Library of New Zealand Te Puna Matauranga o Aotearoa, licensed by the Department of Internal Affairs for re-use under the Creative Commons Attribution 3.0 New Zealand Licence.
Managing the wildlife tourism commons Pirotta, Enrico; Lusseau, David
Ecological applications,
2015-April, 20150401, April 2015, 2015-Apr, 2015-04-00, Letnik:
25, Številka:
3
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The nonlethal effects of wildlife tourism can threaten the conservation status of targeted animal populations. In turn, such resource depletion can compromise the economic viability of the industry. ...Therefore, wildlife tourism exploits resources that can become common pool and that should be managed accordingly. We used a simulation approach to test whether different management regimes (tax, tax and subsidy, cap, cap and trade) could provide socioecologically sustainable solutions. Such schemes are sensitive to errors in estimated management targets. We determined the sensitivity of each scenario to various realistic uncertainties in management implementation and in our knowledge of the population. Scenarios where time quotas were enforced using a tax and subsidy approach, or they were traded between operators were more likely to be sustainable. Importantly, sustainability could be achieved even when operators were assumed to make simple rational economic decisions. We suggest that a combination of the two regimes might offer a robust solution, especially on a small spatial scale and under the control of a self-organized, operator-level institution. Our simulation platform could be parameterized to mimic local conditions and provide a test bed for experimenting different governance solutions in specific case studies.
Techniques recently developed for the analysis of human social networks are applied to the social network of bottlenose dolphins living in Doubtful Sound, New Zealand. We identify communities and ...subcommunities within the dolphin population and present evidence that sex- and age-related homophily play a role in the formation of clusters of preferred companionship. We also identify brokers who act as links between sub-communities and who appear to be crucial to the social cohesion of the population as a whole. The network is found to be similar to human social networks in some respects but different in some others, such as the level of assortative mixing by degree within the population. This difference elucidates some of the means by which the network forms and evolves.
Quantifying the energetic costs of human induced behavioral disturbance on wildlife is a crucial step to evaluate the potential long-term effects of disturbance on individual vital rates. Standard ...methods cannot be used for estimating energetic cost of transport because of the large size of most cetaceans, and instead energetic costs are inferred from respiration rates. We quantified the added energetic costs of avoidance to whale watching boats for minke whales (Balaenoptera acutorostrata) in Faxaflói bay, Iceland, by comparing minke whale movement tracks and respiration in the presence (impact) and absence (control) of whale watching boats. Energy expenditure was inferred from respiration rates, using published bioenergetic models for minke whales and mass-specific cost of transport (COT) was estimated for different swimming speeds. The sensitivity of the COT estimate to model assumptions was investigated using resampling methods. ANCOVA was used to investigate the effects of swimming speed and whale watching boats on minke whale respiration rate. Respiration rate increased linearly with swimming speed, while COT decreased nonlinearly with increased speed up to an optimal speed between 2.5 and 7.0ms−1. Respiration rates were higher during interactions with whale watching boats at any given speed, suggesting that boat presence elicited a stress response in the animals, resulting in a 23.2% increase in estimated energy expenditure. Swimming speed also increased during whale watching interactions from 1.62 to 2.64ms−1, resulting in an additional 4.4% increase in estimated energy expenditure during whale watching interactions. Thus, whale watching boat interactions resulted in an overall increase in estimated energy expenditure of 27.6%, from 56.54 to 72.16Jkg−1min−1. During interactions with whale watching boats, minke whales swam at speeds that were within the lower range of the optimal COT. This suggests that minke whales employ similar avoidance strategies towards whale watching boats as towards natural predators.
•We quantify the energetic costs of whale watching boat avoidance for minke whales.•Energy expenditure was inferred from respiration rates and for different speeds.•Estimated energy expenditure increased during boat interactions by about 28%.•Most of the increase in estimated energy expenditure was attributed to stress.•Whales swam at optimal swimming speeds during boat interactions to outpace boats.
Lay summary: In species that are difficult to observe, activity budgets can be inferred indirectly from other behavioral variables, to assess human induced non-lethal effects on wildlife. We used a ...step-wise modeling approach to quantitatively infer activity states from multiple continuous behavioral data to show that whalewatching boat interactions caused a reduction in the time minke whales spend feeding. The modeling approach provides a means to link short-term behavioral changes to potential long-term bioenergetic consequences in individuals. Lay summary: In species that are difficult to observe, activity budgets can be inferred indirectly from other behavioral variables, to assess human induced non-lethal effects on wildlife. We used a step-wise modeling approach to quantitatively infer activity states from multiple continuous behavioral data to show that whalewatching boat interactions caused a reduction in the time minke whales spend feeding. The modeling approach provides a means to link short-term behavioral changes to potential long-term bioenergetic consequences in individuals.
Unshared consensus decision-making processes, in which one or a small number of individuals make the decision for the rest of a group, are rarely documented. However, this mechanism can be beneficial ...for all group members when one individual has greater knowledge about the benefits of the decision than other group members. Such decisions are reached during certain activity shifts within the population of bottlenose dolphins residing in Doubtful Sound, New Zealand. Behavioral signals are performed by one individual and seem to precipitate shifts in the behavior of the entire group: males perform side flops and initiate traveling bouts while females perform upside-down lobtails and terminate traveling bouts. However, these signals are not observed at all activity shifts. We find that, while side flops were performed by males that have greater knowledge than other male group members, this was not the case for females performing upside-down lobtails. The reason for this could have been that a generally high knowledge about the optimal timing of travel terminations rendered it less important which individual female made the decision.
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