Measured response variables for migrating humpback whale baseline groups and groups exposed to co... more Measured response variables for migrating humpback whale baseline groups and groups exposed to control (vessel only) and full array seismic air gun trials
This file contains the raw song transcriptions for all songs used in every study year (2002-2014)... more This file contains the raw song transcriptions for all songs used in every study year (2002-2014), the data used to create the complexity measures, and the data used to create the individuality metric
Humpback whales likely rely on acoustic communication to mediate social interactions. The distanc... more Humpback whales likely 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 vessel traffic which will mask their social signals. Since no empirical data exists on baleen whale hearing, the consequences of this are usually assumed, being the modelled reduction in their communication space. Here, the communication space and network of migrating humpback whales was compared in increasing wind-dominated and vessel noise. Behavioural data on their social interactions were then used to inform these models. In typical wind noise, a signaller's communication space was estimated to extend to 4 km, which agreed with the maximum separation distance between groups that socially interacted. An increase in vessel noise...
Abstract Acoustic communication is important for animals with dependent young, particularly when ... more Abstract 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 balance a restricted active space with the need to maintain acoustic contact during periods of separation is not yet understood. Here, we analyzed movement metrics of tagged adult female–calf pairs during migration to identify two behavioral states, “resting/milling” and “travelling.” When travelling, these pairs dived synchronously and exhibited little to no spatial separation. Alternatively, adult females had significantly longer dive durations (p < .01) when resting, and while they spent prolonged times at depth, calves would surface several times independently. This demonstrated that these pairs are frequently separated during periods of rest. We then determined whether the call rates and acoustic levels of these pairs increased with more frequent separation, finding that both adult females and calves significantly increased their call rates, but not levels, when resting. We also found that adult female–calf pairs have a restricted active space, with less than 15% of calls estimated to be detectable beyond 2 km. However, as with call level, detection distance did not differ significantly between the two behavioral states. In summary, adult female–calf pairs maintain successful communication during periods of separation by calling more frequently rather than by producing louder calls. This strategy aids in maintaining acoustic contact while simultaneously limiting detectability by conspecifics.
Dataset describing humpback whale joining behaviour before, during and after exposure to vessels,... more Dataset describing humpback whale joining behaviour before, during and after exposure to vessels, various air gun arrays as compared to baseline. Includes data on the physical and social environment.
During migration, humpback whale (Megaptera novaeangliae) adult females and their calves use acou... more 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, maternal females must choose the vocal and/or behavioral strategy that most effectively balances intra-pair communication with male avoidance. Here, we analyzed differences in adult female-calf vocal activity and movement behavior according to the presence of, and distance to, singing whales and other groups likely to contain males. The results of this study found that these pairs make only minimal changes to their vocal behavior in response to nearby males, suggesting that they have instead evolved calls that are naturally difficult to detect (i.e., produced at significantly lower rates and acoustic levels than other whale groups, resulting in ...
Journal of the Acoustical Society of America, 2018
The high-level percussive sounds generated for seismic sea floor exploration have the potential t... more 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 south-eastern Queensland. A 20 cubic inch airgun or 140 cubic inch array of airguns was towed through the study area for 1 hour with the airguns firing every 11 sec (active treatments) or without the airguns operating (controls). Singing activity across each day was measured by counting the number of singing whales within the 10km-radius study area every 10 min, from 0700 to 1700, including during experiments. Singing activity during active periods and controls were compared with each other as well as with pseudo-randomly selected 1 hour periods when experiments were not underway (baseline). Changes in singing effort were also recorded by not...
Women’s participation and completion at veterinary schools has increased globally for the past fe... more 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 faculties in the USA and Canada and 98 accredited faculties in Europe were analyzed. Women occupied 47.9%, 45.5% and 47.5% of the academic positions in Australia/New Zealand, the USA/Canada and Europe, respectively. Compared to their male counterparts, female academics were more likely to hold the lower ranked positions. The gender distribution is skewed toward men in the senior positions at or above associate professor level in all analyzed regions. The findings of this study confirm gender inequality in academic progression meaning there is a continued need to develop strategies to eliminate inequity in veterinary science faculties worldwide.
Journal of the Acoustical Society of America, 2018
An animal communication network involves complex acoustic interactions between multiple senders, ... more 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 within-, and between-, group communication. To generate masking models, and infer communication space, changes in signal-above-noise and frequency content of received humpback whale social sounds were modelled with the combined effect of increasing background noise (wind or vessel-dominated) and distance from the source (signalling whale). Results suggest that the signaler’s communication space in increasing wind-dominated noise (shallow water) was maintained out to approximately 3 km by using a Lombard response. In high wind noise (over 105 dB re 1 μPa; 12–15 knots), the vocal communication space was significantly reduced, though the incr...
The Population Consequences of Disturbance (PCoD) model is a conceptual framework used to assess ... more 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 health, then vital rates, and finally to population-level effects. Despite its simplicity, there are few complete PCoD models available for any marine mammal species due to a lack of data available to parameterize many of the steps. Here, we present an application of the PCoD framework for migrating humpback whales exposed to a simulated commercial seismic survey scenario. We approached the framework in two ways; first, progressing sequentially forwards through the steps and basing our assessment on lactating females. This cohort was considered to be the most vulnerable in terms of energetic costs of disturbance, and most likely to influence an...
The humpback whales that migrate along the east coast of Australia were hunted to near-extinction... more The humpback whales that migrate along the east coast of Australia were hunted to near-extinction in the 1950s and early 1960s. Two independentseries of land-based surveys conducted over the last 25 years during the whales’ northward migration along the Australian coastline havedemonstrated a rapid increase in the size of the population. In 2004 we conducted a survey of the migratory population as a continuation of theseseries of surveys. Two methods of data analysis were used in line with the previous surveys, both for calculation of absolute and relative abundance.We consider the best estimates for 2004 to be 7,090±660 (95% CI) whales with an annual rate of increase of 10.6±0.5% (95% CI) for 1987–2004.The rate of increase agrees with those previously obtained for this population and demonstrates the continuation of a strong post-exploitationrecovery. While there are still some uncertainties concerning the absolute abundance estimate and structure of this population, the rate of an...
Humpback whales rely on acoustic communication to mediate social interactions. The distance to wh... more 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 vessel traffic which will mask their social signals. Since no empirical data exist on baleen whale hearing, the consequences of this are usually assumed, being the modelled reduction in their communication space. Here, the communication space and network of migrating humpback whales was compared in increasing wind-dominated and vessel-dominated noise. Behavioural data on their social interactions were then used to inform these models. In typical wind noise, a signaller's communication space was estimated to extend to 4 km, which agreed with the maximum separation distance between groups that socially interacted. An increase in vessel noi...
Proceedings of the Royal Society B: Biological Sciences, 2019
Vocal communication systems have a set of rules that govern the arrangement of acoustic signals, ... more 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 quantifies features such as connectivity (adjacent signals in a sequence) and recurring patterns. Here, we apply network-based modelling to the complex, hierarchically structured songs of humpback whales ( Megaptera novaeangliae ) from east Australia. Given the song's annual evolving pattern and the cultural conformity of males within a population, network modelling captured the patterns of multiple song types over 13 consecutive years. Song arrangements in each year displayed clear ‘small-world’ network structure, characterized by clusters of highly connected sounds. Transitions between these connected sounds further suggested a combinatio...
This report aims to compare recent population estimates of southern hemisphere breeding stock D h... more 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 practicality of current survey designs, and serves as a reference point for future improvement in whale monitoring strategies (location of surveys, field protocols, etc.).
Measured response variables for migrating humpback whale baseline groups and groups exposed to co... more Measured response variables for migrating humpback whale baseline groups and groups exposed to control (vessel only) and full array seismic air gun trials
This file contains the raw song transcriptions for all songs used in every study year (2002-2014)... more This file contains the raw song transcriptions for all songs used in every study year (2002-2014), the data used to create the complexity measures, and the data used to create the individuality metric
Humpback whales likely rely on acoustic communication to mediate social interactions. The distanc... more Humpback whales likely 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 vessel traffic which will mask their social signals. Since no empirical data exists on baleen whale hearing, the consequences of this are usually assumed, being the modelled reduction in their communication space. Here, the communication space and network of migrating humpback whales was compared in increasing wind-dominated and vessel noise. Behavioural data on their social interactions were then used to inform these models. In typical wind noise, a signaller's communication space was estimated to extend to 4 km, which agreed with the maximum separation distance between groups that socially interacted. An increase in vessel noise...
Abstract Acoustic communication is important for animals with dependent young, particularly when ... more Abstract 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 balance a restricted active space with the need to maintain acoustic contact during periods of separation is not yet understood. Here, we analyzed movement metrics of tagged adult female–calf pairs during migration to identify two behavioral states, “resting/milling” and “travelling.” When travelling, these pairs dived synchronously and exhibited little to no spatial separation. Alternatively, adult females had significantly longer dive durations (p < .01) when resting, and while they spent prolonged times at depth, calves would surface several times independently. This demonstrated that these pairs are frequently separated during periods of rest. We then determined whether the call rates and acoustic levels of these pairs increased with more frequent separation, finding that both adult females and calves significantly increased their call rates, but not levels, when resting. We also found that adult female–calf pairs have a restricted active space, with less than 15% of calls estimated to be detectable beyond 2 km. However, as with call level, detection distance did not differ significantly between the two behavioral states. In summary, adult female–calf pairs maintain successful communication during periods of separation by calling more frequently rather than by producing louder calls. This strategy aids in maintaining acoustic contact while simultaneously limiting detectability by conspecifics.
Dataset describing humpback whale joining behaviour before, during and after exposure to vessels,... more Dataset describing humpback whale joining behaviour before, during and after exposure to vessels, various air gun arrays as compared to baseline. Includes data on the physical and social environment.
During migration, humpback whale (Megaptera novaeangliae) adult females and their calves use acou... more 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, maternal females must choose the vocal and/or behavioral strategy that most effectively balances intra-pair communication with male avoidance. Here, we analyzed differences in adult female-calf vocal activity and movement behavior according to the presence of, and distance to, singing whales and other groups likely to contain males. The results of this study found that these pairs make only minimal changes to their vocal behavior in response to nearby males, suggesting that they have instead evolved calls that are naturally difficult to detect (i.e., produced at significantly lower rates and acoustic levels than other whale groups, resulting in ...
Journal of the Acoustical Society of America, 2018
The high-level percussive sounds generated for seismic sea floor exploration have the potential t... more 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 south-eastern Queensland. A 20 cubic inch airgun or 140 cubic inch array of airguns was towed through the study area for 1 hour with the airguns firing every 11 sec (active treatments) or without the airguns operating (controls). Singing activity across each day was measured by counting the number of singing whales within the 10km-radius study area every 10 min, from 0700 to 1700, including during experiments. Singing activity during active periods and controls were compared with each other as well as with pseudo-randomly selected 1 hour periods when experiments were not underway (baseline). Changes in singing effort were also recorded by not...
Women’s participation and completion at veterinary schools has increased globally for the past fe... more 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 faculties in the USA and Canada and 98 accredited faculties in Europe were analyzed. Women occupied 47.9%, 45.5% and 47.5% of the academic positions in Australia/New Zealand, the USA/Canada and Europe, respectively. Compared to their male counterparts, female academics were more likely to hold the lower ranked positions. The gender distribution is skewed toward men in the senior positions at or above associate professor level in all analyzed regions. The findings of this study confirm gender inequality in academic progression meaning there is a continued need to develop strategies to eliminate inequity in veterinary science faculties worldwide.
Journal of the Acoustical Society of America, 2018
An animal communication network involves complex acoustic interactions between multiple senders, ... more 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 within-, and between-, group communication. To generate masking models, and infer communication space, changes in signal-above-noise and frequency content of received humpback whale social sounds were modelled with the combined effect of increasing background noise (wind or vessel-dominated) and distance from the source (signalling whale). Results suggest that the signaler’s communication space in increasing wind-dominated noise (shallow water) was maintained out to approximately 3 km by using a Lombard response. In high wind noise (over 105 dB re 1 μPa; 12–15 knots), the vocal communication space was significantly reduced, though the incr...
The Population Consequences of Disturbance (PCoD) model is a conceptual framework used to assess ... more 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 health, then vital rates, and finally to population-level effects. Despite its simplicity, there are few complete PCoD models available for any marine mammal species due to a lack of data available to parameterize many of the steps. Here, we present an application of the PCoD framework for migrating humpback whales exposed to a simulated commercial seismic survey scenario. We approached the framework in two ways; first, progressing sequentially forwards through the steps and basing our assessment on lactating females. This cohort was considered to be the most vulnerable in terms of energetic costs of disturbance, and most likely to influence an...
The humpback whales that migrate along the east coast of Australia were hunted to near-extinction... more The humpback whales that migrate along the east coast of Australia were hunted to near-extinction in the 1950s and early 1960s. Two independentseries of land-based surveys conducted over the last 25 years during the whales’ northward migration along the Australian coastline havedemonstrated a rapid increase in the size of the population. In 2004 we conducted a survey of the migratory population as a continuation of theseseries of surveys. Two methods of data analysis were used in line with the previous surveys, both for calculation of absolute and relative abundance.We consider the best estimates for 2004 to be 7,090±660 (95% CI) whales with an annual rate of increase of 10.6±0.5% (95% CI) for 1987–2004.The rate of increase agrees with those previously obtained for this population and demonstrates the continuation of a strong post-exploitationrecovery. While there are still some uncertainties concerning the absolute abundance estimate and structure of this population, the rate of an...
Humpback whales rely on acoustic communication to mediate social interactions. The distance to wh... more 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 vessel traffic which will mask their social signals. Since no empirical data exist on baleen whale hearing, the consequences of this are usually assumed, being the modelled reduction in their communication space. Here, the communication space and network of migrating humpback whales was compared in increasing wind-dominated and vessel-dominated noise. Behavioural data on their social interactions were then used to inform these models. In typical wind noise, a signaller's communication space was estimated to extend to 4 km, which agreed with the maximum separation distance between groups that socially interacted. An increase in vessel noi...
Proceedings of the Royal Society B: Biological Sciences, 2019
Vocal communication systems have a set of rules that govern the arrangement of acoustic signals, ... more 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 quantifies features such as connectivity (adjacent signals in a sequence) and recurring patterns. Here, we apply network-based modelling to the complex, hierarchically structured songs of humpback whales ( Megaptera novaeangliae ) from east Australia. Given the song's annual evolving pattern and the cultural conformity of males within a population, network modelling captured the patterns of multiple song types over 13 consecutive years. Song arrangements in each year displayed clear ‘small-world’ network structure, characterized by clusters of highly connected sounds. Transitions between these connected sounds further suggested a combinatio...
This report aims to compare recent population estimates of southern hemisphere breeding stock D h... more 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 practicality of current survey designs, and serves as a reference point for future improvement in whale monitoring strategies (location of surveys, field protocols, etc.).
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Papers by Rebecca Dunlop