Rebecca A. Dunlop

• BSc PhD
• The University of Queensland

Bottlenose dolphins produce individually distinctive signature whistles (SWs) to broadcast identity. Stability of the SW frequency contour is essential to preserve identity information; however, SWs could carry additional information which requires variability. We used acoustic recordings from provisioned free-swimming Indo-Pacific bottlenose dolph...

Health information is essential for the conservation management of whale species. However, assessing the health of free‐ranging whales is challenging as samples are primarily limited to skin and blubber tissue. Reverse transcription quantitative polymerase chain reaction (RT‐qPCR) offers a method to measure health from blubber RNA, providing insigh...

Baleen whale sound perception is an important factor to consider when predicting and mitigating the impacts of anthropogenic ocean noise. Some sound types, for example predator calls, may elicit greater responses, meaning whale behavior is not only driven by proximity and received level, but other factors. Here, we compared the response of migratin...

During the project “Behavioural Response of Australian Humpback whales to Seismic Surveys” three air gun configurations were used to quantify the response of southerly migrating humpback whales to a northerly travelling air gun. Off Peregian Beach, Queensland (26.5o S latitude) a 20 cubic inch (cui) single air gun, 440 cui and 3130 cui arrays were...

There is concern that noise from “airguns” used during oil and gas exploration may cause behavioral changes in marine mammals. One important behavior of some mysticete whales is the production of songs which are likely used as reproductive displays. Humpback whales have conspicuous songs but there are few studies on the impact of noise on their sin...

Currently, there are no direct data on mysticete hearing in noise. Available data comes from anatomical modelling, the assumption they can hear their own sounds, and studies on the effects of various sources of anthropogenic noise on their behavior. This study used a behavioral response study design to quantify humpback whale hearing in natural oce...

Animal communication systems evolved in the presence of noise generated by natural sources. Many species can increase the source levels of their sounds to maintain effective communication in elevated noise conditions, i.e. they have a Lombard response. Human activities generate additional noise in the environment creating further challenges for the...

Recent studies have shown behavioural plasticity in mating strategies can increase a population’s ability to cope with anthropogenic impacts. The eastern Australian humpback whale population was whaled almost to extinction in the 1960s (~200 whales) and has recovered to pre-whaling numbers (>20,000 whales). Using an 18-year dataset, where the popul...

An introduction to acoustic and vibrational communication in animals is presented in this chapter. Starting with the origins of communication and ritualization of vocal and vibrational signals to produce a clear message or broadcast. A summary of communication concepts is presented describing behaviors such as displays. The chapter continues by unr...

The best practices for conducting bioacoustical research are described in this chapter. Ethical considerations, including the need for research integrity, animal ethics (e.g., in the USA, the Institutional Animal Care and Use Committee, IACUC) approvals, and data management and archiving are discussed. Suggestions for conducting a bioacoustical stu...

The songs produced by male humpback whales are believed to be a reproductive display shared by all singers within the same population. Ocean noise can interfere with the transmission of acoustic signals such as humpback whale songs. However, humpback whales evolved in an environment characterised by variable levels of noise generated by natural sou...

The large size of free-ranging mysticetes, such as humpback whales (Megaptera novaeangliae), make capture and release health assessments unfeasible for conservation research. However, individual energetic condition or reproductive health may be assessed from the gene expression of remotely biopsied tissue. To do this, researchers must reliably extr...

Humpback whalesHumpback whale(Megaptera novaeangliae)Megaptera novaeangliae occur in all major oceans. Given this worldwide distribution, and since they tend to migrate along coastlines, they are one of the best known of the baleen whalesBaleen whale. Humpbacks are relatively easy to find and easy to observe. This, along with their surface behavior...

Despite the increased entry of women into the veterinary profession over the past several decades, women remain substantially underrepresented in senior leadership positions. This may include editorial positions at veterinary sciences journals. This study examines the gender distribution of editorships of 143 journals from the Thomson Reuters Web o...

Acoustic communication is important for animals with dependent young, particularly when they are spatially separated. Maternal humpback whales (Megaptera novaeangliae) use acoustic calling to help minimize the risk of separation from their young calves during migration. These pairs also use acoustic crypsis to minimize detection by males. How they...

Gender disparities in academia have been highlighted as a significant issue in many fields and differences in the senior positions are particularly significant, particularly in the STEM disciplines. This has been further amplified by the COVID-19 pandemic with an overall lower research productivity of female academic compared to men. In veterinary...

Intraspecific conflict can be costly; therefore, many species engage in ritualized contests composed of several stages. Each stage is typically characterized by different levels of aggression, arousal, and physical conflict. During these different levels of “intensity,” animals benefit from communicating potential information related to features su...

Women’s participation and completion at veterinary schools has increased globally for the past few decades. However, increased female graduates have not translated into similar patterns of academic staffing. The gender distribution within each academic level at eight accredited veterinary faculties in Australia and New Zealand, 38 accredited facult...

Conspicuous signals, such as acoustic sexual signals, can be “risky” in that they may be overheard by competitors. This means the signaller must balance the benefits of signaling to the intended receiver with the costs of providing information to these competitors. Depending on the signaller context, this balance may change. Male humpback whales pr...

Animals may communicate potential information to conspecifics using stereotyped “discrete” calls and variable “graded” calls. However, animal vocal research often centers on identifying the number of call types in a repertoire rather than quantifying the amount of gradation. Here, fuzzy clustering was applied to the social call repertoire of a spec...

During migration, humpback whale (Megaptera novaeangliae) adult females and their calves use acoustic calling to help maintain contact. The signals produced by these pairs, however, may unintentionally attract nearby breeding males, which can result in interactions that have negative physical and physiological effects on the calf. Therefore, matern...

The Population Consequences of Disturbance (PCoD) model is a conceptual framework used to assess the potential for population-level consequences following exposure of animals to a disturbance activity or stressor. This framework is a four-step process, progressing from changes in individual behavior and/or physiology, to changes in individual healt...

In many terrestrial species, there is a relationship between the acoustic features of vocal signals and the underlying motivational state and arousal level of the signaller. This information may be particularly important during complex social interactions, which are common in species where males compete for access to females during the breeding sea...

• Bottlenose dolphins encountered around the Irish coast are considered part of a wide‐ranging coastal community; however, knowledge on the significance of the north of Ireland for this species is limited by a lack of dedicated effort. • Through social media, the opportunity now exists to gather large volumes of citizen science data in the form of...

Understanding the interactions between human activity in the ocean and marine mammals is a fundamental step to developing responsible mitigation measures and informing policy. Here, the response of migrating humpback whales to vessels towing seismic air gun arrays (on or off) was quantified as a reduction in their likelihood of socially interacting...

Humpback whale (Megaptera novaeangliae) calf survival during migration is dependent upon them maintaining contact with their mothers, and acoustics likely plays a significant role in this. Here, we analysed calls (n = 255) produced by migrating humpback whale adult female-calf pairs (n = 15) off the east coast of Australia. First, we identified nin...

Baleen whales are vulnerable to environmental impacts due to low fecundity, capital breeding strategies, and their reliance on a large amount of prey resources over large spatial scales. There has been growing interest in monitoring health and physiological stress in these species but, to date, few measures have been validated. The purpose of this...

Vocal communication systems have a set of rules that govern the arrangement of acoustic signals, broadly defined as 'syntax'. However, there is a limited understanding of potentially shared or analogous rules across vocal displays in different taxa. Recent work on songbirds has investigated syntax using network-based modelling. This technique quant...

1. The designation of protected sites for cetaceans has been largely shaped by patterns in site fidelity, often favouring species with clear residency patterns or highly localised breeding and foraging areas. 2. Conservation of the harbour porpoise , a species that does not typically exhibit strong patterns in site fidelity, has been challenging....

Humpback whales rely on acoustic communication to mediate social interactions. The distance to which these social signals propagate from the signaller defines its communication space, and therefore communication network (number of potential receivers). As humpback whales migrate along populated coastlines, they are likely to encounter noise from ve...

For most cetacean species, there is little known about how an individual's physiology influences its behaviour. Humpback whales (Megaptera novaeangliae) are a good candidate to examine such links as they have a well-described distribution and behaviour, can be consistently sampled using remote biopsy systems, and have been the subject of several pr...

This report aims to compare recent population estimates of southern hemisphere breeding stock D humpback whales (Megaptera novaeangliae) based on data collected at two key locations along the Western Australian coastline, namely North West Cape (NWC) and Shark Bay, ~400 km south of NWC. The report additionally investigates the efficacy and practica...

Despite heavy overexploitation and near extirpation, some populations of large whales are recovering. Monitoring their recovery has important implications for conservation, management and our understanding of population dynamics and recovery in large mammals. The eastern Australian population of humpback whales was hunted to near‐extirpation by the...

Source level and frequency are important in determining how far an acoustic signal can travel. However, in some species these sound characteristics have been found to be biomechanically linked, and therefore cannot be modified independently to achieve optimal transmission. This study investigates the variability in source levels and their relations...

Blubber and respiratory vapour (‘blow’) are now commonly used for endocrine studies on cetaceans, primarily because they can be obtained using minimally invasive methods. For many species, these samples have yet to be validated for these purposes. The objective of this study was to examine the performance of blow and blubber hormone monitoring, rel...

Much evidence for non-human culture comes from vocally learned displays, such as the vocal dialects and song displays of birds and cetaceans. While many oscine birds use song complexity to assess male fitness, the role of complexity in humpback whale (Megaptera novaeangliae) song is uncertain owing to population-wide conformity to one song pattern....

The effective management and conservation of animal populations relies on statistically-sound and replicable surveys to obtain estimates of abundance and assess trends. Surveys of cetaceans, such as humpback whales Megaptera novaeangliae, are difficult to conduct and are particularly affected by bias in detection probability. For example, the proba...

The high-level percussive sounds generated for seismic sea floor exploration have the potential to disrupt normal behaviors of whales. This study assesses if there is any reduction in the singing behaviour of migrating humpback whales in response to nearby airguns. Singing whales were acoustically tracked as they migrated along the coastline of sou...

An animal communication network involves complex acoustic interactions between multiple senders, receivers, and eavesdroppers. Any reduction in communication space, due to signal masking, may have detrimental effects on their ability to obtain social information. Humpback whales use social sounds (vocal and surface-generated percussive sounds) for...

Marine mammals (whales, dolphins, seals, sea lions, sea cows) use sound both actively and passively to communicate and sense their environment, covering frequencies from a few hertz to greater than 100 kHz, differing with species. Although a few documents on marine mammal sound production and reception date back 200 years, concern about the effects...

The behavioural responses of migrating humpback whales to an air gun, a small clustered seismic array and a commercial array were used to develop a dose-response model, accounting for the presence of the vessel, array towpath relative to the migration and social and environmental parameters. Whale groups were more likely to show an avoidance respon...

In animal social networks, a large acoustic communication space tends to involve complex networks. Signal masking may reduce this space, leading to detrimental effects on the animal's ability to obtain important social information. Humpback whales use acoustic social sounds (vocal sounds and surface-generated sounds from breaching or fin slapping)...

Male humpback whales produce a mating display called “song.” Behavioral studies indicate song has inter- and/or intra-sexual functionality, suggesting song may be a multi-message display. Multi-message displays often include stereotypic components that convey group membership for mate attraction and/or male-male interactions, and complex components...

Despite concerns on the effects of noise from seismic survey airguns on marine organisms, there remains uncertainty as to the biological significance of any response. This study quantifies and interprets the response of migrating humpback whales (Megaptera novaeangliae) to a 3130 in3 (51.3l) commercial airgun array. We compare the behavioural respo...

Between the 1940s and 1970s Southern Hemisphere populations of humpback whales (including eastern Australia and Oceania populations) were hunted to near extinction by extensive commercial whaling activities in Antarctica, with fewer whales taken in shore whaling operations in New Zealand, Australia (including Norfolk Island) and Tonga. Variable rat...

Classification of vocal signals can be undertaken using a wide variety of qualitative and quantitative techniques. Using east Australian humpback whale song from 2002 to 2014, a subset of vocal signals was acoustically measured and then classified using a Self-Organizing Map (SOM). The SOM created (1) an acoustic dictionary of units representing th...

The study of marine soundscapes is a growing field of research. Recording hardware is becoming more accessible; there are a number of off-the-shelf autonomous recorders that can be deployed for months at a time; software analysis tools exist as shareware; raw or preprocessed recordings are freely and publicly available. However, what is missing are...

Acoustic surveys of vocal animals can have significant advantages over visual surveys, particularly for marine mammals. For acoustic density estimates to be viable, however, the vocal output of the animals surveyed needs to be determined under a range of conditions and shown to be a robust predictor of abundance. In this study, the songs of humpbac...

The effect of various anthropogenic sources of noise (e.g. sonar, seismic surveys) on the behaviour of marine mammals is sometimes quantified as a dose-response relationship, where the probability of an animal behaviourally 'responding' (e.g. avoiding the source) increases with 'dose' (or received level of noise). To do this, however, requires a de...

The vocalizations of nonhuman animals are considered potential indicators of motivational or internal state. In many species, different call types, and structural variation within call types, encode information about physical characteristics such as age or sex, or about variable traits such as motivation. Domestic chickens, Gallus gallus, have an e...

Mating displays often have the dual function of mediating male-male interactions and facilitating female choice. Animals may accomplish this dual functionality by producing multi-message acoustic displays that contain structurally distinct components. These displays typically combine a stereotypic component that conveys species or group identity wi...

Acoustic signals in terrestrial animals follow motivational-structural rules to inform receivers of the signaler's motivational state, valence and level of arousal. Low-frequency “harsh” signals are produced in aggressive contexts, whereas high-frequency tonal sounds are produced in fearful/appeasement contexts. Using the non-song social call catal...

The humpback whale (Megaptera novaeangliae) makes annual migrations from Antarctic feeding grounds to tropical breeding grounds. The extent to which it feeds during migration is unknown, but thought to be very low. Whether an animal feeds during migration is likely dependent on prey availability and on the ease with which it can capture the availab...

When measuring the response of large whales to a noise source, multiple measures of behavior are often used (e.g. horizontal movement, dive profile and surface behavior). Although this helps to determine fine-scale changes in behavior, using numerous measures means an adjustment of significance level. In addition, many of these behavioral measures...

Animal vocal repertoires can be varied and complex, and it is often difficult to obtain a comprehensive picture. One of the primary reasons for this difficulty stems from the classification of acoustic signals, which has typically relied on qualitative and subjective methods. Vocal signals (units) were measured from east Australian humpback whale s...

Balancing the costs and benefits of emitting a mating signal is complex. There are direct costs, such as time taken away from essential activities like feeding, and indirect costs, such as attracting unintended receivers, who may gain advantageous information from eavesdropping. As a consequence, the signaler may reduce his chances of mating if the...

Humpback whale studies support inter- and/or intrasexual song functions, suggesting dual functionality. Some animals produce multi-message displays with dual functionality. Stereotyped components, for mate attraction and/or male-male interactions, convey species/group membership. Variable components, for courtship, convey male quality. If humpback...

As part of their social sound repertoire, migrating humpback whales (Megaptera novaeangliae) perform a large variety of surface-active behaviors, such as breaching and repetitive slapping of the pectoral fins and tail flukes; however, little is known about what factors influence these behaviors and what their functions might be. We investigated the...

Small research vessels are often used as platforms for tagging activities to collect behavioral data on cetaceans and they have the potential to disturb that group or individual. If this disturbance is ignored, results and conclusions produced by that study could be inaccurate. Here land-based behavioral data of migrating humpback whales (Megaptera...

Humpback whales (Megaptera novaeangliae) undertake one of the longest migrations of any animal and while on a broad-scale this journey appears direct, on a fine-scale, behaviors associated with socializing and breeding are regularly observed. However, little is known about which social and environmental factors influence behavior during this time....

Four major experiments have been conducted off Australia to quantify the behavioral response of migrating humpback whales to various seismic air gun arrays. The first, using a 20 in³ air gun, was used to develop the analysis framework, which was then applied to later experiments. The following two experiments tested a 4-step “ramp-up” procedure (20...

Acoustic surveys of marine mammals have several advantages over traditional visual surveys. For an acoustic survey to be accurate, however, there needs to be a predictable relationship between vocal behavior and density. Humpback whale’s song, produced by males primarily during the breeding season, is potentially a good candidate for such surveys....

Many theories and communication models developed from terrestrial studies focus on a simple dyadic exchange between a sender and receiver. During social interactions, the “frequency code” hypothesis suggests that frequency characteristics of vocal signals can simultaneously encode for static signaler attributes (size or sex) and dynamic information...

In animal behaviour studies, particularly those involving wild animals, the reliability and valid- ity of behavioural data collected by observers are not often examined. It is rarer still to see an assessment of the factors that may influence data collection. Variation in the reliability (the con- sistency of measurements) and the validity (the...

The modification of communication signals in response to a changing noise environment has been demonstrated in many terrestrial species, although there are comparatively fewer studies in marine mammals. It is rare, even in terrestrial studies, that the response to an anthropogenic source of noise is compared with a natural source of noise in order...

In animal behaviour studies, particularly those involving wild animals, the reliability and valid-ity of behavioural data collected by observers are not often examined. It is rarer still to see an assessment of the factors that may influence data collection. Variation in the reliability (the con-sistency of measurements) and the validity (the accur...

Mating displays often contain acoustic signals that function in female choice and/or mediate male-male interactions. Many animals, such as birds, use multi-message displays that contain structurally distinct song types with these different functions. Mate attraction/male-male competition songs convey species identification and sender locations over...

For terrestrial migrants, feeding at migratory stopover sites is important, with prey quality linked to future survival and reproductive success. In contrast, the importance of this behaviour to marine species is unknown. The humpback whale Megaptera novaeangliae is a marine migrant that is thought to fast while migrating; however, recent studies s...

The songs of humpback whales (Megaptera novaeagliae) are one of the best models of large-scale cultural transmission in a non-human animal. Humpback whale song is complex in part due to the multiple levels of arrangement, and the constantly changing nature of the display. Both small evolutionary and large revolutionary changes can occur to the song...

Seismic surveys are widely used for exploration for oil and gas deposits below the sea floor. Despite concern they may have an impact on whale behaviour, our knowledge of marine mammal responses is limited. In the first of a series of experiments (the last one involving a full seismic array), this study tested the response of migrating humpback wha...

There is little disagreement among regulators, scientists, and other interested parties as to the complexity surrounding our understanding of the potential and realized impacts of anthropogenic noise on marine life. Given the challenges of research in an aquatic environment, the breadth of species of interest and the range of human-made noise-produ...

Studying the behavioral response of whales to noise presents numerous challenges. In addition to the characteristics of the noise exposure, many factors may affect the response and these must be measured and accounted for in the analysis. An adequate sample size that includes matching controls is crucial if meaningful results are to be obtained. Fi...

Multiple platform approaches for measuring the behavior of marine mammals may strengthen data quality and quantity. However, if this approach is chosen, reconciliation of behavioral measures between each platform is required. This study compared typical measures of humpback whale (Megaptera novaeangliae) behavior collected from three different samp...

The movement of marine animals feeding at the sea surface is restricted by wave drag and a reduction in propulsive efficiency. Many rorqual whale species lunge feed at the surface, yet existing methodologies for detecting lunges in accelerometer data have not been applied to surface-feeding behavior. Our study aimed to develop a method to detect su...

The use of stereotyped calls within structured bouts has been described for a number of species and may increase the information potential of call repertoires. Humpback whales produce a repertoire of social calls, although little is known about the complexity or function of these calls. In this study, digital acoustic tag recordings were used to in...

'Ramp-up', or 'soft start', is a mitigation measure used in seismic surveys and involves increasing the radiated sound level over 20-40. min. This study compared the behavioural response in migrating humpback whales to the first stages of ramp-up with the response to a 'constant' source, 'controls' (in which the array was towed but not operated) wi...

The extensive territorial waters of Australia and New Zealands (NZ) (over 8 million km2 for Australia and a further 4 million km2 for NZ) are home to approximately 49 species of whales and dolphins, 11 species of seals and the dugong. Within Australia, at least eight species are listed as threatened, though there is insufficient information on a fu...

The Lombard reflex is an increase in the subject's vocal levels in response to increased noise levels. This functions to maintain an adequate signal-to-noise ratio at the position of the receiver when noise levels vary. While it has been demonstrated in a small number of mammals and birds including some whales, it has not yet been shown to occur in...

The source level of an animal sound is important in communication, since it affects the distance over which the sound is audible. Several measurements of source levels of whale sounds have been reported, but the accuracy of many is limited because the distance to the source and the acoustic transmission loss were estimated rather than measured. Thi...

A study of the responses of humpback whales to seismic air guns is being conducted in Australian waters and two of four major experiments have been completed. It aims to assess the impact of seismic surveys on the whales and the effectiveness of ramp-up in mitigation. In separate trials, whales were exposed to a 20 cu in air gun, ramp-up in level f...

In acoustic communication, high background noise is an important obstacle in successful receiver signal detection and perception of an intended acoustic signal. To overcome this problem, many animals modify acoustic signals by increasing the repetition rate, duration, amplitude, or frequency range of the signal. Humpback whales are the most vocal o...

Quantifying the stability of a species vocal repertoire is fundamental for further investigations into repertoire function and geographic variation. Changes to the repertoire of sounds used in the song displays of male humpback whales have been well studied. In contrast, little is known about the stability of this species' non-song vocal calls. The...

The concern about the effects of the noise of human activities on marine mammals, particularly whales, has led to a substantial amount of research but there is still much that is not understood, particularly in terms of the behavioural responses to noise and the longer term biological consequences of these responses. There are many challenges in co...

The behavioural response study (BRS) is an experimental design used by field biologists to determine the function and /or behavioural effects of conspecific, heterospecific or anthropogenic stimuli. When carrying out these studies in marine mammals it is difficult to make basic observations and achieve sufficient samples sizes due to the high cost...

The Lombard reflex is an increase in the subject's vocal levels in response to increased noise levels. While it has been demonstrated in humans and a small number of mammals and birds including some whales, it has not been demonstrated in humpback whales. During their southward migration off eastern Australia humpback whales were tracked visually f...

Two large behavioral response studies (BRS) have been conducted with humpback whales migrating along the east Australian coastline (in project BRAHSS: Behavioural Response of Australian Humpback Whales to Seismic Surveys). Whales were exposed to four stages of ramp-up with nominally 6 dB increase in level at each step, and a hard start nominally 12...

The BRAHSS (Behavioural Response of Australian Humpback Whales to Seismic Surveys) series of experiments uses a multi-platform approach to determine the behavioural and acoustic response of humpbacks to noise from seismic air gun arrays. One of the data collection platforms utilises the DTAG, or acoustic digital recording tag. DTAGs are small sucti...

The behavioral-response study (BRS) is an experimental design used by field biologists to determine the function and/or behavioral effects of conspecific, heterospecific, or anthropogenic stimuli. Although this has been used for many years in studies of acoustic stimuli and whales, many of these studies have been limited by lack of true replication...

The first of four major experiments in project behavioural response of australian humpback whales to seismic surveys (BRAHSS) was conducted on the east coast of Australia in September and October 2010. The project aims to understand how humpback whales respond to seismic surveys and to provide the information that will allow these surveys to be con...

Single platform aerial line transect and land-based surveys of Breeding Stock 'D' humpback whales Megaptera novaeangliae were undertaken to provide absolute abundance estimates of animals migrating northward along the western Australian coast. The aerial survey flew a total of 28 flights, of which 26 were completed successfully, from 24 th June-19...