Fleur Visser

Fleur Visser
Kelp Marine Research

PhD

About

61
Publications
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1,199
Citations

Publications

Publications (61)
Article
Closely-related species are expected to diverge in foraging strategy, reflecting the evolutionary drive to optimize foraging performance. The most speciose cetacean genus, the mesoplodonts, are beaked whales with little diversity in external morphology or diet, and overlapping distributions. Moreover, the few studied species of beaked whales (Ziphi...
Article
Full-text available
The detection and use of emitters’ signals by unintended receivers, i.e., eavesdropping, represents an important and often low-cost way for animals to gather information from their environment. Acoustic eavesdropping can be a key driver in mediating intra- and interspecific interactions (e.g., cooperation, predator–prey systems), specifically in sp...
Article
Despite their enormous size, whales make their living as voracious predators. To catch their much smaller, more maneuverable prey, they have developed several unique locomotor strategies that require high energetic input, high mechanical power output and a surprising degree of agility. To better understand how body size affects maneuverability at t...
Article
Full-text available
Human noise can be harmful to sound-centric marine mammals. Significant research has focused on characterizing behavioral responses of protected cetacean species to navy mid-frequency active sonar (MFAS). Controlled exposure experiments (CEE) using animal-borne tags have proved valuable, but smaller dolphins are not amenable to tagging and groups o...
Article
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Foraging decisions of deep-diving cetaceans can provide fundamental insight into food web dynamics of the deep pelagic ocean. Cetacean optimal foraging entails a tight balance between oxygen-conserving dive strategies and access to deep-dwelling prey of sufficient energetic reward. Risso's dolphins ( Grampus griseus ) displayed a thus far unknown d...
Article
Full-text available
In today's marine habitats, anthropogenic noise is widespread in space and time, affecting aquatic animal communities. Short-term exposure to noise is known to affect vital behaviours, such as the ability to evade predators. However, long-term noise pollution may lead to differences in short-term responses between naïve and experienced animals. We...
Article
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Group-living animals must communicate to stay in contact. In long-finned pilot whales, there is a trade-off between the benefits of foraging individually at depth and the formation of tight social groups at the surface. Using theoretical modelling and empirical data of tagged pairs within a group, we examined the potential of pilot whale social cal...
Article
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Fear of predation can induce profound changes in the behaviour and physiology of prey species even if predator encounters are infrequent. For echolocating toothed whales, the use of sound to forage exposes them to detection by eavesdropping predators, but while some species exploit social defences or produce cryptic acoustic signals, deep-diving be...
Article
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The largest animals are marine filter feeders, but the underlying mechanism of their large size remains unexplained. We measured feeding performance and prey quality to demonstrate how whale gigantism is driven by the interplay of prey abundance and harvesting mechanisms that increase prey capture rates and energy intake. The foraging efficiency of...
Article
Toothed whales have evolved flexible biosonar systems to find, track and capture prey in diverse habitats. Delphinids and phocoenids adjust inter-click intervals and source levels gradually while approaching prey. In contrast, deep-diving beaked and sperm whales maintain relatively constant inter-click intervals and apparent output levels during th...
Article
How predators maximize energetic gains while minimizing the costs associated with exploiting heterogeneous prey remains a difficult ecological principle to test in natural systems. Deep‐diving, air‐breathing predators face conflicting demands of oxygen conservation to extend dive time and oxygen usage from the exercise required to find and capture...
Article
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Killer whales (KW) may be predators or competitors of other cetaceans. Since their foraging behavior and acoustics differ among populations (‘ecotypes’), we hypothesized that other cetaceans can eavesdrop on KW sounds and adjust their behavior according to the KW ecotype. We performed playback experiments on long-finned pilot whales (Globicephala m...
Preprint
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Animals aggregate to obtain a range of fitness benefits, but a common cost of aggregation is increased detection by predators. Here we show that, in contrast to visual and chemical signallers, aggregated acoustic signallers need not face higher predator encounter rate. This is the case for prey groups that synchronize vocal behaviour but have negli...
Article
Full-text available
Time allocation to different activities and habitats enables individuals to modulate their perceived risks and access to resources and can reveal important trade-offs between fitness-enhancing activities (e.g., feeding vs. social behavior). Species with long reproductive cycles and high parental investment, such as marine mammals, rely on such beha...
Article
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Exposure to underwater sound can cause permanent hearing loss and other physiological effects in marine animals. To reduce this risk, naval sonars are sometimes gradually increased in intensity at the start of transmission (‘ramp-up’). Here, we conducted experiments in which tagged humpback whales were approached with a ship to test whether a sonar...
Article
Full-text available
Vocalisations form a key component of the social interactions and foraging behaviour of toothed whales. We investigated changes in calling and echolocation behaviour of long-finned pilot whales between foraging and non-foraging periods, by combining acoustic recordings and diving depth data from tagged individuals with concurrent surface observatio...
Article
Minke whales are difficult to study and little information exists regarding their responses to anthropogenic sound. This study pools data from behavioural response studies off California and Norway. Data are derived from four tagged animals, of which one from each location was exposed to naval sonar signals. Statistical analyses were conducted usin...
Article
Vocalizations of cetaceans form a key component of their social interactions. Such vocalization activity is driven by the behavioral states of the whales, which are not directly observable, so that latent-state models are natural candidates for modeling empirical data on vocalizations. In this paper, hidden Markov models are used to analyze calling...
Article
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Modern long-range naval sonars are a potential disturbance for marine mammals and can cause disruption of feeding in cetaceans. We examined the lunge-feeding behaviour of humpback whales Megaptera novaeangliae before, during and after controlled exposure experiments with naval sonar by use of acoustic and motion sensor archival tags attached to eac...
Article
Full-text available
A key issue when investigating effects of anthropogenic noise on cetacean behavior is to identify the biological significance of the responses. Predator presence can be considered a natural high-level disturbance stimulus to which prey animals have evolved adaptive response strategies to reduce their risk of predation by altering behavior away from...
Article
The Southern California Behavioral Response Study (SOCAL-BRS) is an interdisciplinary, multi-team collaboration that uses high-resolution, multi-sensor tags to document behavioral responses of cetaceans to Navy mid-frequency (2.5-5 kHz) active sonar (MFAS). Individual animals are monitored before, during, and after controlled exposure experiments (...
Article
Full-text available
Early studies that categorized odontocete pulsed sounds had few means of discriminating signals used for biosonar-based foraging from those used for communication. This capability to identify the function of sounds is important for understanding and interpreting behavior; it is also essential for monitoring and mitigating potential disturbance from...
Article
Full-text available
Social interactions among animals can influence their response to disturbance. We investigated responses of long-finned pilot whales to killer whale sound playbacks and two anthropogenic sources of disturbance: tagging effort and naval sonar exposure. The acoustic scene and diving behaviour of tagged individuals were recorded along with the social...
Article
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During the construction of a gas pipeline from an offshore gas field in northwest Ireland, a year-round shore-based marine mammal monitoring programme was undertaken. Using 6 yr of data, generalised estimating equations-generalised additive models (GEE-GAMs) were used to investigate if construction-related activity and vessel traffic influenced the...
Article
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Controlled exposure experiments using 1 to 2 kHz, sonar signals were conducted with 11 humpback whales (Megaptera novaeangliae), one minke whale (Balaertoptera acutorostrata), and one northern bottlenose whale (Hyperoodon ampullatus) during three field trials from 2011 to 2013. Ship approaches without sonar transmissions, playbacks of killer whale...
Article
In mitigating the risk of sonar operations, the behavioral response of cetaceans is one of the major knowledge gaps that needs to be addressed. The 3S-Project has conducted a number of controlled exposure experiments with a realistic sonar source in Norwegian waters from 2006 to 2013. In total, the following six target species have been studied: ki...
Article
Full-text available
Although northern bottlenose whales were the most heavily hunted beaked whale, we have little information about this species in its remote habitat of the North Atlantic Ocean. Underwater anthropogenic noise and disruption of their natural habitat may be major threats, given the sensitivity of other beaked whales to such noise disturbance. We attach...
Article
Full-text available
Anti-predator strategies are often defined as 'flight' or 'fight', based upon prey anatomical adaptations for size, morphology and weapons, as well as observed behaviours in the presence of predators. The humpback whale Megaptera nova eangliae is considered a 'fight' specialist based upon anatomy and observations of grouping behaviour and active de...
Article
Full-text available
Bottlenose dolphin stock structure in the northeast Atlantic remains poorly understood. However, fine scale photo-id data have shown that populations can comprise multiple overlapping social communities. These social communities form structural elements of bottlenose dolphin (Tursiops truncates) populations, reflecting specific ecological and behav...
Article
Anti-predator strategies are often defined as ‘flight’ or ‘fight’, based upon prey anatomical adaptations for size, morphology and weapons, as well as observed behaviours in the presence of predators. The humpback whale \textitMegaptera novaeangliae is considered a ‘fight’ specialist based upon anatomy and observations of grouping behaviour and act...
Article
Cetacean sound-production rates are highly variable and patchy in time, depending upon individual behavior, social context, and environmental context. Better quantification of the drivers of this variability should allow more realistic estimates of expected call rates, improving our ability to convert between call counts and animal density, and als...
Article
Long-finned pilot whales (Globicephala melas) are highly social cetaceans that live in matrilineal groups and acquire their prey during deep foraging dives. We tagged individual pilot whales to record their diving behaviour. To describe the social context of this individual behaviour, the tag data were matched with surface observations at the group...
Presentation
Due to their cryptic surface behaviour and preference for remote, deep-water habitats, Sowerby’s beaked whales (Mesoplodon bidens) remain among the most poorly studied cetaceans in the world. To increase our understanding of their behaviour and ecology, we investigated group characteristics, depth distribution and vocalisations of Sowerby’s beaked...
Article
Full-text available
Inter-specific behavioral interactions between large whales and small odontocetes are rarely described and little understood. Reasons for such associations have been proposed but are difficult to substantiate empirically given the challenges inherent with studying deep- and long-diving cetaceans at sea. Proposed reasons include some of those descri...
Article
Full-text available
Marine construction works often lead to temporary increases in vessel traffic, which, in addition to the construction activity itself, contribute to underwater ambient noise in the affected area and increase the risk of vessel collision for marine mammals. Using a 3 yr data set of cliff-based observations, we investigated whether the presence/absen...
Article
Full-text available
Interactions between individuals of different cetacean species are often observed in the wild. Killer whales (Orcinus orca) can be potential predators of many other cetaceans, and the interception of their vocalizations by unintended cetacean receivers may trigger anti-predator behavior that could mediate predator-prey interactions. We explored the...
Article
Full-text available
In cetaceans' communities, interactions between individuals of different species are often observed in the wild. Yet, due to methodological and technical challenges very little is known about the mediation of these interactions and their effect on cetaceans' behavior. Killer whales (Orcinus orca) are a highly vocal species and can be both food comp...
Data
Protocol details, method for reaction score and group size analyses and estimation of the sound pressure levels received by the whales. (DOC)
Data
Distances between tagged whale gm10_158d and the sound source during CTRL playback (left) and KW playback (right) experiments. Dotted lines: distances obtained projecting movement based upon sightings in the 10 min-period prior to the start of each playback. Solid lines: actual distances. rs: reaction score, defining as the difference between dista...
Data
Results of the GEE models on reaction score and change of group size, with both independent variables: playback order and stimulus type. Shown are estimates, their standard errors (s.d.), and p-values (before and after Jackknife estimator). (DOC)
Article
Full-text available
Long-term monitoring programmes of a comparatively small area complement larger scale, but temporally limited surveys and can provide extensive datasets on seasonal occurrence and fine-scale habitat use of multiple species. A marine mammal monitoring programme, involving year-round, land-based observations, has been conducted in Broadhaven Bay cand...
Article
Full-text available
This study describes behavioral changes of wild cetaceans observed during controlled exposures of naval sonar. In 2006 through 2009, 14 experiments were conducted with killer (n = 4), long-finned pilot (n = 6), and sperm (n = 4) whales. A total of 14 6-7 kHz upsweep, 13 1-2 kHz upsweep, and five 1-2 kHz downsweep sonar exposures, as well as seven S...
Article
Full-text available
Each year, a phytoplankton spring bloom starts just north of the North Atlantic Subtropical Gyre, and then expands northwards across the entire North Atlantic. Here, we investigate whether the timing of the spring migration of baleen whales is related to the timing of the phytoplankton spring bloom, using 4 yr of dedicated whale observations at the...
Technical Report
Full-text available
In this report, we document the methods and outcome of a series of experiments in which cetaceans were exposed to naval sonar signals. We were motivated to conduct these experiments because there exists a combination of concern that sonars have strong negative effects on cetaceans, and a lack of information about what negative effects might occur a...
Article
Full-text available
Behavioral responses of Risso's dolphins (Grampus griseus) to whale watching vessels were studied off Pico Island, Azores. Dolphin behavior was studied from a land-based lookout, enabling observations of groups in the absence and presence of vessels. The number of whale watching vessels showed a clear seasonal pattern, dividing the whale watching p...
Article
Full-text available
In this study, we present for the first time a model for the social structure of Risso's dolphins (Grampus griseus Cuvier, 1812). Over the period 2004-2006, 1028 Risso's dolphins were identified at Pico island, Azores. Individuals sighted on 10 or more occasions were included in the analysis of social structure (n = 183). High resighting rates indi...
Article
The atmosphere is widely recognized as a major source of Fe in the form of iron-containing dust. This study provides the first experiments in which the impact of dust on the growth rates of single species of Antarctic diatoms was assessed under laboratory conditions. The dust was among others characterized by x-ray powder diffraction analysis, anal...

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