Magnus Wahlberg

Magnus Wahlberg
University of Southern Denmark | SDU · Department of Biology

About

147
Publications
48,814
Reads
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5,088
Citations
Citations since 2016
50 Research Items
2620 Citations
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20162017201820192020202120220100200300400

Publications

Publications (147)
Article
Full-text available
High numbers of harbor porpoises (Phocoena phocoena) end up as bycatch in gillnets every year. Acoustic alarms (pingers) have been demonstrated to be an efficient mitigation tool to prevent bycatch of this species; however, little is known about the behavioral reactions of wild porpoises to pingers. This knowledge is important for optimizing the de...
Article
Full-text available
Penguins are known to react to underwater noise, but it is unknown if they make use of sound cues while diving. We tested if captive gentoo penguins (Pygoscelis papua) can pair underwater sounds with food through Pavlovian conditioning. Two seconds after an underwater sound (a 1-4kHz sweep with a received level of 130 dB re 1 µPa rms) was played ba...
Article
Full-text available
In-air and underwater audiograms and directional hearing abilities were measured in humans. The lowest underwater thresholds were 2.8 µW/m² or 3.6 mPa at a frequency of 500 Hz. The underwater hearing thresholds were 4-26 dB and 40-62 dB higher than in-air hearing thresholds when measured in intensity and pressure units, respectively. This differenc...
Article
Full-text available
Nineteen female silver European eels (Anguilla anguilla L.) were tagged with satellite tags and released in the Gulf of Lion in the Mediterranean during the migration seasons 2013 and 2015. Sixteen tags transmitted data: five in the Atlantic Ocean, and eleven in the Mediterranean. Of those, 50% of migrating eels were consumed by marine mammals in e...
Article
Full-text available
Capsule Great Cormorants Phalacrocorax carbo sinensis use vocal communication during the breeding season, with males being particularly vocal earlier in the breeding cycle and showing individual variation in some calls, which could be used for individual recognition. Aims To identify and describe vocal behaviour of Great Cormorants, to link calls...
Article
Full-text available
The harbor porpoise, Phocoena phocoena , is the only cetacean regularly occurring in the Baltic Sea. During the last decades, several anthropogenic activities have affected porpoises in the Baltic region. Most notably is bycatch in static fishing gear, such as gill nets, which is the main human-induced cause of death in odontocetes. There is still...
Article
Full-text available
Empirical measurements of odontocete hearing are limited to captive individuals, constituting a fraction of species across the suborder. Data from more species could be available if such measurements were collected from unrestrained animals in the wild. This study investigated whether electrophysiological hearing data could be recorded from a train...
Article
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Understanding jellyfish ecology and roles in coastal ecosystems is challenging due to their patchy distribution. While standard net sampling or manned aircraft surveys are inefficient, Unmanned Aerial Vehicles (UAVs) or drones represent a promising alternative for data collection. In this technical report, we used pictures taken from a small drone...
Article
Full-text available
Toothed whales use powerful ultrasonic biosonar pulses (i.e. clicks) for echolocation. Underwater acoustic recordings have suggested that the majority of toothed whale species can be grouped acoustically as either producing broadband clicks or narrowband high-frequency (NBHF) clicks. Recently, it has been shown that Heaviside’s dolphins, Cephalorhy...
Article
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Cooperative hunting involves individual predators relating in time and space to each other’s actions to more efficiently track down and catch prey. The evolution of advanced cognitive abilities and sociality in animals are strongly associated with cooperative hunting abilities, as has been shown in lions, chimpanzees and dolphins. Much less is know...
Article
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Male harbor seals (Phoca vitulina) produce stereotypic underwater roars during the mating season. It remains unclear to what extent roar structures vary due to predation levels. Here, seal roars from waters with many (Iceland) and few (Denmark and Sweden) predators were compared. Most Icelandic roars included a long pulse train and a pause. Iceland...
Article
Full-text available
Wild harbour porpoises (Phocoena phocoena) mainly forage during the night and, because they rely on echolocation to detect their prey, this is also when they are most acoustically active. It has been hypothesised that this activity pattern is a response to the diel behaviour of their major prey species. To test this hypothesis, we monitored the aco...
Article
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Cuttlefish are highly efficient predators, which strongly rely on their anterior binocular visual field for hunting and prey capture. Their complex eyes possess adaptations for low light conditions. Recently, it was discovered that they display camouflaging behavior at night, perhaps to avoid detection by predators, or to increase their nighttime h...
Article
Marine mammals have fine-tuned hearing abilities, which makes them vulnerable to human-induced sounds from shipping, sonars, pile drivers, and air guns. Many species of marine birds, such as penguins, auks, and cormorants, find their food underwater where light is often limited, suggesting sound detection may play a vital role. Yet, for most marine...
Article
Full-text available
Marine mammals and diving birds face several physiological challenges under water, affecting their thermoregulation and locomotion as well as their sensory systems. Therefore, marine mammals have modified ears for improved underwater hearing. Underwater hearing in birds has been studied in a few species, but for the record-holding divers, such as p...
Article
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Diving birds spend up to several minutes underwater during pursuit-dive foraging. To find and capture prey, like fish and squid, they probably need several senses in addition to vision. Cormorants, very efficient predators of fishes, have unexpectedly low visual acuity underwater. So, underwater hearing may be an important sense, as for other divin...
Poster
Full-text available
Master´s Thesis. Poster presented at the 2nd World Marine Mammal Conference (WMMC), Barcelona, Spain. December 2019.
Article
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Pinnipeds are aquatic predators feeding on a vast range of prey, and their social behaviour differs greatly between species (from extreme polygyny in some sea lions to monogamy in some true seals). It has been hypothesised that the foraging and social complexity of their lifestyle should drive the evolution of their cognitive abilities. To investig...
Article
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The lack of interest among pre-university students to choose STEM subjects for their higher education is a heavily debated issue in many western-world countries. To boost Danish students’ interest in biology, a study event on artificial reefs was introduced when teaching marine biology in lower secondary school and upper secondary school (student a...
Article
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During last decades, anthropogenic underwater sound and its chronic impact on marine species have been recognised as an environmental protection challenge. At the same time, studies on the spatial and temporal variability of ambient sound, and how it is affected by biotic, abiotic and anthropogenic factors are lacking. This paper presents analysis...
Conference Paper
Seabirds are perhaps the most imperiled group of birds. They can readily transit between air and water and enact key behaviors in both habitats. With this amphibious lifestyle, they likely face unique auditory constraints in air, underwater, and even subterranean. Unfortunately, like many other birds, anthropogenic noise seems to be a stressor, yet...
Article
Full-text available
Hearing is a primary sensory modality for birds. For seabirds, auditory data is challenging to obtain and hearing data are limited. Here, we present methods to measure seabird hearing in the field, using two Alcid species: the common murre Uria aalge and the Atlantic puffin Fratercula arctica Tests were conducted in a portable semi-anechoic crate u...
Article
The problem-solving capabilities of four small parrots (peach-fronted conures, Eupsittula aurea) were investigated using string-pulling tests. In seven different tasks, one string was baited following a randomized order. The parrots could retrieve the food reward after a wrong choice as the choice was not forced. Additionally, we applied a non-intu...
Article
Reliable estimates of field metabolic rates (FMRs) in wild animals are essential for quantifying their ecological roles, as well as for evaluating fitness consequences of anthropogenic disturbances. Yet, standard methods for measuring FMR are difficult to use on free-ranging cetaceans whose FMR may deviate substantially from scaling predictions usi...
Article
Full-text available
• Whale watching can affect cetacean behaviour, and can in some cases lead to long‐term negative effects on survival and reproduction. • The waters of Juneau (Alaska) represent a summer feeding ground for the Central North Pacific stock of humpback whales, Megaptera novaeangliae (Borowski, 1781). The recent dramatic expansion of the local whale‐wat...
Article
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New methods are needed to attract more interest to natural sciences among the public and young people. We established an underwater laboratory by placing cameras on an artificial reef (a sunken ferry) to create a new and inspiring way of teaching marine biology and showing science to the public. Here we describe the process and solutions to the tec...
Poster
In cetaceans, growth curves and season-dependent morphometric measurements are usually obtained from stranded or bycaught individuals, with little longitudinal data available. This may bias interpretations on age - and sex-related growth as well as on health status. Here long-term growth and seasonal variations in body size were measured on captive...
Article
Full-text available
In-air hearing in birds has been thoroughly investigated. Sound provides birds with auditory information for species and individual recognition from their complex vocalizations, as well as cues while foraging and for avoiding predators. Some 10% of existing species of birds obtain their food under the water surface. Whether some of these birds make...
Poster
Full-text available
The population of grey seals (Halichoerus grypus) is increasing in German and Danish waters, causing large concerns for their impact on fisheries and the current status of fish stocks. In 2014, the grey seal population was 32,000 individuals and has continued to increase in the following years1. Little is known about grey seal feeding habits as wel...
Article
Little is known about underwater hearing abilities of diving birds. To help fill this gap we measured audiograms of cormorants (Phalacrocorax carbo) using two different methods. Wild-caught cormorant fledglings were anesthetized and their auditory brainstem responses (ABR) to clicks and tone bursts were measured; first in an anechoic box in air and...
Poster
Full-text available
The harbor porpoise (Phocoena phocoena) is one of the smallest species of cetaceans. They populate temperate and Arctic waters with large temperature fluctuations between seasons. Therefore, this is a marine mammal characterized by extreme blubber accumulations in preparation for cold winter conditions. As blubber has a smaller density than sea wat...
Article
Full-text available
Many aquatic birds use sounds extensively for in-air communication. Regardless of this, we know very little about their hearing abilities. The in-air audiogram of a male adult great cormorant (Phalacrocorax carbo) was determined using psychophysical methods (method of constants). Hearing thresholds were derived using pure tones of five different fr...
Article
Male harbor seals gather around breeding sites for competitive mating displays. Here, they produce underwater vocalizations possibly to attract females and/or scare off other males. These calls offer prospects for passive acoustic monitoring. Acoustic monitoring requires a good understanding of natural variation in calling behavior both temporally...
Article
Full-text available
Hearing is the primary sensory modality for toothed whales, but it is not known at which age it is fully developed. For newborn calves, hearing could fill an important function in maintaining contact with the mother and to develop echolocation skills. We non-invasively measured the auditory brainstem response (ABR) in two neonate (age 1-4 days) and...
Article
Significance statement: Passive listening is the predominant method for examining brain activity during echolocation, the auditory analysis of self-generated sounds. We show that sighted humans perform better when they actively vocalize than during passive listening. Correspondingly, vocal motor and cerebellar activity is greater during active ech...
Chapter
As an acoustic signal travels from the source to a receiver, it is affected by a variety of physical processes, all dictated by properties of the signal and the environment. The signal energy is weakened by geometric attenuation as well as absorption by the medium. The temporal and spectral properties can be modified by sound absorption, refraction...
Chapter
There is no difference in principle between the infrasonic and ultrasonic sounds which are inaudible to humans (or other animals) and the sounds that we can hear. In all cases, sound is a wave of pressure and particle oscillations propagating through an elastic medium, such as air. This chapter is about the physical laws that govern how animals pro...
Conference Paper
Psychoacoustic and electrophysiological methods were used to measure the in-air hearing sensitivity of the great cormorant (Phalacrocorax carbo sinensis). One individual was used to determine the behavioral thresholds, which was then compared to previously collected data on the auditory brainstem response (ABR) thresholds from 11 individuals. The b...
Article
In 2012, two marine mammal welfare and well-being workshops were held: one from 19-21 March 2012 at the Harderwijk Dolfinarium in the Netherlands, and the other from 9-11 November 2012 at Hubbs-SeaWorld Research Institute in San Diego, California. Well over 150 international participants attended, from Europe as well as North America. Herein, we pr...
Poster
Full-text available
To measure the in-air hearing sensitivity of the cormorant using psychophysics and compare the results to previously obtained auditory brainstem response thresholds.
Poster
Full-text available
In this study we investigate basic cognitive skills of four specimens, two males (M1 and M2) and two females (F1 and F2) using the string-pulling test. A reward is suspended by a length of string, which is attached to the underside of a perch. The food cannot be taken by flying or standing on the ground. By varying spatial configurations of baited...
Conference Paper
Full-text available
The underwater hearing threshold of a great cormorant (Phalacrocroax carbo sinensis) was measured at 2 kHz using psychophysical methods. Previous in-air and underwater testing suggests that cormorants have rather poor in-air hearing compared to other birds of similar size (Johansen, 2016). Preliminary data with a new underwater paradigm in a larger...
Conference Paper
The C-POD logger is a widely used instrument for passive acoustic monitoring of harbor porpoises, but the absence of a continuous recording in this device makes it difficult to verify its performance. An alternative but more labor-intensive approach is to use a wideband sound recorder and off-line detection software. Here we compare the performance...
Article
Full-text available
Sperm whales produce codas for communication that can be grouped into different types according to their temporal patterns. Codas have led researchers to propose that sperm whales belong to distinct cultural clans, but it is presently unclear if they also convey individual information. Coda clicks comprise a series of pulses and the delay between p...
Presentation
Full-text available
Sperm whales produce stereotyped click series, called codas, for communication that can be grouped into different types according to their temporal patterns. These distinctive phonations have led researchers to propose that sperm whales belong to distinct cultural clans, but it is presently unclear if they also convey individual information for com...
Presentation
Full-text available
The Azores supported a sperm whaling industry for over one century and presently host a growing whale watching industry that mainly targets this species. Despite the lower productivity in relation to other coastal areas, the waters around the Azores are one important feeding ground for the species in the North Atlantic. Yet, very little is known ab...
Article
Full-text available
Management of the impact of underwater sound is an emerging concern worldwide. Several countries are in the process of implementing regulatory legislations. In Europe, the Marine Strategy Framework Directive was launched in 2008. This framework addresses noise impacts and the recommendation is to deal with it on a regional level. The Baltic Sea is...
Article
Full-text available
Hearing thresholds of a great cormorant (Phalacrocorax carbo) were measured in air and under water using psychophysics. The lowest thresholds were at 2 kHz (45 dB re 20 μPa root-mean-square [rms] in air and 79 dB re 1 μPa rms in water). Auditory brainstem response measurements on one anesthetized bird in air indicated an audiogram with a shape that...
Article
Full-text available
The behaviour of adult, male sperm whales in polar waters (69 20 N, 15 40 E) during exposure to pulses from ar emote (>20km) seismic survey vessel and artificial codas is described and discussed. Five hours of recordings with al arge aperture array contained both air gun pulses and sperm whale clicks. The seismic survey pulses received were smeared...
Conference Paper
Full-text available
The interest in passive acoustic monitoring (PAM) techniques has increased dramatically in cetacean research during last decade. Nowadays potential applications do not include only ecology projects (abundance, seasonality, foraging ecology) but also the risk assessment of human activities (wind farm construction, seismic survey). Therefore, the cur...
Data
LabVIEW (2012 version) source code files for the National Instruments PXIE-6358 system, sampling 48 AD channels at 500 kHz/channel. An independent multifunction USB device (National Instruments USB-6251) delivered a trigger pulse for the PXIE system alongside a high-frequency pulse (a frequency-modulated sweep) that was transmitted into the water t...
Article
Full-text available
Toothed whales use sonar to detect, locate, and track prey. They adjust emitted sound intensity, auditory sensitivity and click rate to target range, and terminate prey pursuits with high-repetition-rate, low-intensity buzzes. However, their narrow acoustic field of view (FOV) is considered stable throughout target approach, which could facilitate...
Article
Echolocating animals exercise an extensive control over the spectral and temporal properties of their biosonar signals to facilitate perception of their actively generated auditory scene when homing in on prey. The intensity and directionality of the biosonar beam defines the field of view of echolocating animals by affecting the acoustic detection...
Article
Full-text available
Wahlberg and his colleagues explore the concept of Umwelt, the comprehensive picture of the world an animal forms from all of its senses as it relates to the acoustic abilities of the harbor porpoise. This close connection has allowed them to tease out details of how the animals produce sounds, as well as how they hear and echolocate simultaneously...
Conference Paper
Full-text available
Some echolocation signal parameters can be studied using a single receiver. However, studying parameters such as source level, directionality, and direction of signal emission require the use of multi-receiver arrays. Acoustic localization allows for determination of the position of echolocators at the time of signal emission, and when multiple ani...
Chapter
The signals emitted by echolocating bats and toothed whales can be of very impressive intensity. Actually, some of the most intense vocalizations of any mammal is found in the echolocation calls of bats and whales. Here we collect the known literature of so-called source levels (the sound intensity measured at a reference distance in front of the a...
Article
Full-text available
Marine management plans over the world express high expectations to the development of offshore wind energy. This would obviously contribute to renewable energy production, but potential conflicts with other usages of the marine landscape, as well as conservation interests, are evident. The present study synthesizes the current state of understandi...
Article
Museums, science centres and other visitor attractions find inspiration for development from many sources, including their own guests. This article describes a guest experiment undertaken at a Danish marine science centre. It was found that mussels represent a captivating topic of interpretation with many aspects. However, guests are generally very...
Article
Full-text available
Toothed whales and bats have independently evolved biosonar systems to navigate and locate and catch prey. Such active sensing allows them to operate in darkness, but with the potential cost of warning prey by the emission of intense ultrasonic signals. At least six orders of nocturnal insects have independently evolved ears sensitive to ultrasound...
Article
Full-text available
Sperm whales produce different click types for echolocation and communication. Usual clicks and buzzes appear to be used primarily in foraging while codas are thought to function in social communication. The function of slow clicks is less clear, but they appear to be produced by males at higher latitudes, where they primarily forage solitarily, an...
Article
Full-text available
The harbor porpoise is one of the smallest and most widely spread of all toothed whales. They are found abundantly in coastal waters all around the northern hemisphere. They are among the 11 species known to use high frequency sonar of relative narrow bandwidth. Their narrow biosonar beam helps isolate echoes from prey among those from unwanted ite...
Article
Full-text available
Nielsen et al. (2012; Mar Ecol Prog Ser 453:241-248) analyzed surface observations of harbour porpoises in a small coastal area where a modified gillnet was introduced at randomized time intervals. The study concluded that porpoises reacted to the gillnet at surprisingly large distances (in some cases >80 m). Dawson & Lusseau (2013; Mar Ecol Prog S...
Article
Full-text available
Visually dominant animals use gaze adjustments to organize perceptual inputs for cognitive processing. Thereby they manage the massive sensory load from complex and noisy scenes. Echolocation, as an active sensory system, may provide more opportunities to control such information flow by adjusting the properties of the sound source. However, most s...
Article
Full-text available
During echolocation, toothed whales produce ultrasonic clicks at extremely rapid rates and listen for the returning echoes. The auditory brainstem response (ABR) duration was evaluated in terms of latency between single peaks: 5.5 ms (from peak I to VII), 3.4 ms (I-VI), and 1.4 ms (II-IV). In comparison to the killer whale and the bottlenose dolphi...