Acoustic recording tags provide insight into the springtime acoustic behavior of sei whales in Massachusetts Bay.

The acoustic ecology of sei whales (Balaenoptera borealis) is poorly understood due to limited direct observation of the behavioral context of sound production and individual behavior. Suction cup-attached acoustic recording tags were deployed on sei whales to unambiguously assign call types and explore the acoustic behavior of this endangered species. Twelve tag deployments resulted in ∼173 h of acoustic data and 1030 calls. Sound types included downsweeps and three previously undescribed call types. Knocks were short duration (<1 s), with an average peak frequency of 330 Hz. Pulse type 1 and pulse type 2 calls, typically produced in sequences, were short in duration (0.08 and 0.28 s) and low in average peak frequency (50 and 26 Hz), with relatively high received levels. Average call rates for all call types combined were three calls per hour, but increased during twilight. Sex differences in call type usage included a higher use of pulses by females and knocks by males. Calls were almost exclusively produced at depths <10 m, although whales rarely dove deeper in this study. These data provide a more comprehensive picture of the acoustic and behavioral ecology of sei whales than previously possible, which can inform future conservation efforts for this endangered species.

Phenological changes in North Atlantic right whale habitat use in Massachusetts Bay.

The North Atlantic right whale (Eubalaena glacialis) is one of the world's most highly endangered baleen whales, with approximately 400-450 individuals remaining. Massachusetts Bay (MB) and Cape Cod Bay (CCB) together comprise one of seven areas in the Gulf of Maine where right whales seasonally congregate. Here, we report on acoustically detected presence of right whales in MB over a nearly 6 year period, July 2007-April 2013, a time of both rapid ocean warming throughout the Gulf of Maine and apparent changes in right whale migratory dynamics. We applied an automated detection algorithm to assess hourly presence of right whale "up-calls" in recordings from a 19-channel acoustic array covering approximately 4,000 km2 in MB. Over the survey, up-calls were detected in 95% of 8 day periods. In each year, as expected, we observed a "peak season" of elevated up-call detections in late winter and early spring corresponding to the season when right whales congregate to feed in CCB. However, we also saw an increase in right whale occurrence during time periods thought to be part of the "off-season." With the exception of 2009-2010, when acoustic presence was unusually low, the mean percent of hours in which up-calls were detected increased every year, both during the peak season (from 38% in 2008 to 70% in 2012), and during the summer-fall season (from 2% in 2007 to 13% in 2012). Over the entire study, the peak season start date varied between 17 January and 26 February. Changes in right whale phenology in MB likely reflect broadscale changes in habitat use in other areas within the species range. This study demonstrates the value of continuous long-term survey datasets to detect and quantify shifts in cetacean habitat use as environmental conditions change and the long-term continued survival of right whales remains uncertain.

Exploring movement patterns and changing distributions of baleen whales in the western North Atlantic using a decade of passive acoustic data.

Six baleen whale species are found in the temperate western North Atlantic Ocean, with limited information existing on the distribution and movement patterns for most. There is mounting evidence of distributional shifts in many species, including marine mammals, likely because of climate-driven changes in ocean temperature and circulation. Previous acoustic studies examined the occurrence of minke (Balaenoptera acutorostrata) and North Atlantic right whales (NARW; Eubalaena glacialis). This study assesses the acoustic presence of humpback (Megaptera novaeangliae), sei (B. borealis), fin (B. physalus), and blue whales (B. musculus) over a decade, based on daily detections of their vocalizations. Data collected from 2004 to 2014 on 281 bottom-mounted recorders, totaling 35,033 days, were processed using automated detection software and screened for each species' presence. A published study on NARW acoustics revealed significant changes in occurrence patterns between the periods of 2004-2010 and 2011-2014; therefore, these same time periods were examined here. All four species were present from the Southeast United States to Greenland; humpback whales were also present in the Caribbean. All species occurred throughout all regions in the winter, suggesting that baleen whales are widely distributed during these months. Each of the species showed significant changes in acoustic occurrence after 2010. Similar to NARWs, sei whales had higher acoustic occurrence in mid-Atlantic regions after 2010. Fin, blue, and sei whales were more frequently detected in the northern latitudes of the study area after 2010. Despite this general northward shift, all four species were detected less on the Scotian Shelf area after 2010, matching documented shifts in prey availability in this region. A decade of acoustic observations have shown important distributional changes over the range of baleen whales, mirroring known climatic shifts and identifying new habitats that will require further protection from anthropogenic threats like fixed fishing gear, shipping, and noise pollution.

Acoustically advertising male harbour seals in southeast Alaska do not make biologically relevant acoustic adjustments in the presence of vessel noise.

Aquatically breeding harbour seal (Phoca vitulina) males use underwater vocalizations during the breeding season to establish underwater territories, defend territories against intruder males, and possibly to attract females. Vessel noise overlaps in frequency with these vocalizations and could negatively impact breeding success by limiting communication space. In this study, we investigated whether harbour seals employed anti-masking strategies to maintain communication in the presence of vessel noise in Glacier Bay National Park and Preserve, Alaska. Harbour seals in this location did not sufficiently adjust source levels or acoustic parameters of vocalizations to compensate for acoustic masking. Instead, for every 1 dB increase in ambient noise, signal excess decreased by 0.84 dB, indicating a reduction in communication space when vessels passed. We suggest that harbour seals may already be acoustically advertising at or near a biologically maximal sound level and therefore lack the ability to increase call amplitude to adjust to changes in their acoustic environment. This may have significant implications for this aquatically breeding pinniped, particularly for populations in high noise regions.

Animal-borne tags provide insights into the acoustic communication of southern right whales (Eubalaena australis) on the calving grounds.

This study investigated the repertoire, call-type variability and call rates of southern right whales on a calving ground off Brazil in the western South Atlantic. Acoustic tag data were collected from four lactating females and one juvenile. Pulsive, hybrid, and upcalls showed the greatest variability among call-types with up to 23% of non-standard forms detected. Quiet sounds (grunt, single, and double pulse) were detected for the first time in this species on the calving grounds. Although the sample size was limited, results suggest that social interaction increased call-type diversity and call rates, in line with other acoustic studies on right whales.

Acoustic crypsis in communication by North Atlantic right whale mother-calf pairs on the calving grounds.

Mammals with dependent young often rely on cryptic behaviour to avoid detection by potential predators. In the mysticetes, large baleen whales, young calves are known to be vulnerable to direct predation from both shark and orca predators; therefore, it is possible that mother-calf pairs may show cryptic behaviours to avoid the attention of predators. Baleen whales primarily communicate through low-frequency acoustic signals, which can travel over long ranges. In this study, we explore the potential for acoustic crypsis, a form of cryptic behaviour to avoid predator detection, in North Atlantic right whale mother-calf pairs. We predicted that mother-calf pairs would either show reduced calling rates, reduced call amplitude or a combination of these behavioural modifications when compared with other demographic groups in the same habitat. Our results show that right whale mother-calf pairs have a strong shift in repertoire usage, significantly reducing the number of higher amplitude, long-distance communication signals they produced when compared with juvenile and pregnant whales in the same habitat. These observations show that right whale mother-calf pairs rely upon acoustic crypsis, potentially to minimize the risk of acoustic eavesdropping by predators.

North Atlantic right whale (Eubalaena glacialis) acoustic behavior on the calving grounds.

Passive acoustic monitoring is a common method for detection of endangered North Atlantic right whales. This study reports on the acoustic behavior of right whales on the winter calving grounds to assess their acoustic detectability in this habitat. In addition to known call types, previously undescribed low amplitude short broadband signals were detected from lactating females with calves. The production of higher amplitude tonal calls occurred at lower rates for lactating females than from other age/sex classes suggesting that passive acoustic monitoring may be less effective in detecting mother-calf pairs in this critical habitat area.

Frogs adapt to physiologically costly anthropogenic noise.

Human activities impose novel pressures on amphibians, which are experiencing unprecedented global declines, yet population-level responses are poorly understood. A growing body of literature has revealed that noise is an anthropogenic stressor that impacts ecological processes spanning subcellular to ecosystem levels. These consequences can impose novel selective pressures on populations, yet whether populations can adapt to noise is unknown. We tested for adaptation to traffic noise, a widespread sensory 'pollutant'. We collected eggs of wood frogs (Rana sylvatica) from populations from different traffic noise regimes, reared hatchlings under the same conditions, and tested frogs for differences in sublethal fitness-relevant effects of noise. We show that prolonged noise impaired production of antimicrobial peptides associated with defence against disease. Additionally, noise and origin site interacted to impact immune and stress responses. Noise exposure altered leucocyte production and increased baseline levels of the stress-relevant glucocorticoid, corticosterone, in frogs from quiet sites, but noise-legacy populations were unaffected. These results suggest noise-legacy populations have adapted to avoid fitness-relevant physiological costs of traffic noise. These findings advance our understanding of the consequences of novel soundscapes and reveal a pathway by which anthropogenic disturbance can enable adaptation to novel environments.

Source levels and call parameters of harbor seal breeding vocalizations near a terrestrial haulout site in Glacier Bay National Park and Preserve.

Source levels of harbor seal breeding vocalizations were estimated using a three-element planar hydrophone array near the Beardslee Islands in Glacier Bay National Park and Preserve, Alaska. The average source level for these calls was 144 dBRMS re 1 µPa at 1 m in the 40-500 Hz frequency band. Source level estimates ranged from 129 to 149 dBRMS re 1 µPa. Four call parameters, including minimum frequency, peak frequency, total duration, and pulse duration, were also measured. These measurements indicated that breeding vocalizations of harbor seals near the Beardslee Islands of Glacier Bay National Park are similar in duration (average total duration: 4.8 s, average pulse duration: 3.0 s) to previously reported values from other populations, but are 170-220 Hz lower in average minimum frequency (78 Hz).

Evidence for ship noise impacts on humpback whale foraging behaviour.

Noise from shipping activity in North Atlantic coastal waters has been steadily increasing and is an area of growing conservation concern, as it has the potential to disrupt the behaviour of marine organisms. This study examines the impacts of ship noise on bottom foraging humpback whales (Megaptera novaeangliae) in the western North Atlantic. Data were collected from 10 foraging whales using non-invasive archival tags that simultaneously recorded underwater movements and the acoustic environment at the whale. Using mixed models, we assess the effects of ship noise on seven parameters of their feeding behaviours. Independent variables included the presence or absence of ship noise and the received level of ship noise at the whale. We found significant effects on foraging, including slower descent rates and fewer side-roll feeding events per dive with increasing ship noise. During 5 of 18 ship passages, dives without side-rolls were observed. These findings indicate that humpback whales on Stellwagen Bank, an area with chronically elevated levels of shipping traffic, significantly change foraging activity when exposed to high levels of ship noise. This measureable reduction in within-dive foraging effort of individual whales could potentially lead to population-level impacts of shipping noise on baleen whale foraging success.

Anthropogenic Noise and Physiological Stress in Wildlife.

The ecological impacts of increasing levels of anthropogenic noise in marine and freshwater systems are of growing public interest. Recent emphasis on the physiological approaches to identifying the impacts of noise has led to increased recognition that anthropogenic noise is an environmental stressor. We briefly review the research on noise-induced physiological stress. Additionally, we summarize findings from a controlled playback experiment that explored the relationship between traffic noise and physiological stress in anurans (frogs and toads), an aquatic group that relies on acoustic communication for survival and reproduction.

Humans, Fish, and Whales: How Right Whales Modify Calling Behavior in Response to Shifting Background Noise Conditions.

This study investigates the role of behavioral plasticity in the variation of sound production of southern right whales (Eubalaena australis) in response to changes in the ambient background noise conditions. Data were collected from southern right whales in Brazilian waters in October and November 2011. The goal of this study was to quantify differences in right whale vocalizations recorded in low background noise as a control, fish chorus noise, and vessel noise. Variation in call parameters were detected among the three background noise conditions and have implications for future studies of noise effects on whale sound production.

Quantitative analysis of the acoustic repertoire of southern right whales in New Zealand.

Quantitatively describing the acoustic repertoire of a species is important for establishing effective passive acoustic monitoring programs and developing automated call detectors. This process is particularly important when the study site is remote and visual surveys are not cost effective. Little is known about the vocal behavior of southern right whales (Eubalaena australis) in New Zealand. The aim of this study was to describe and quantify their entire vocal repertoire on calving grounds in the sub-Antarctic Auckland Islands. Over three austral winters (2010-2012), 4349 calls were recorded, measured, and classified into 10 call types. The most frequently observed types were pulsive, upcall, and tonal low vocalizations. A long tonal low call (≤15.5 s duration) and a very high call (peak frequency ∼750 Hz) were described for the first time. Random Forest multivariate analysis of 28 measured variables was used to classify calls with a high degree of accuracy (82%). The most important variables for classification were maximum ceiling frequency, number of inflection points, duration, and the difference between the start and end frequency. This classification system proved to be a repeatable, fast, and objective method for categorising right whale calls and shows promise for other vocal taxa.

Vocalizations produced by southern right whale (Eubalaena australis) mother-calf pairs in a calving ground off Brazil.

Aiming to gather information on southern right whale (Eubalaena australis) mother-calf pairs' vocal behavior, archival acoustic recorders were deployed at a calving area off Brazil. Manual inspection of spectrograms revealed seven call classes: upcall, downcall, down-upcall, tonal variable, tonal constant, hybrid, and pulsive calls, which are consistent with those previously described for this species in Argentina. Gunshots and warbles, vocalizations described from other right whale species, were not detected. Mean values of start, end, maximum, minimum and peak frequencies, frequency bandwidth and duration were calculated for each call class. Start and end frequencies, frequency bandwidth and duration of upcalls recorded off Brazil were compared to those from other right whale populations and species. Only mean duration of upcalls from Brazil were significantly different from upcalls from all other populations. Differences in call duration may be driven by differences in demographic factors or background noise features among study areas. The repertoire characterization presented in this study will contribute to increase the utility of passive acoustic monitoring as a tool for conservation and research of southern right whales off Brazil as it provides important baseline information on the vocal behavior of this species.

Modification of spectral features by nonhuman primates.

Ackermann et al. discuss the lack of evidence for vocal control in nonhuman primates. We suggest that nonhuman primates may be capable of achieving greater vocal control than previously supposed. In support of this assertion, we discuss new evidence that nonhuman primates are capable of modifying spectral features in their vocalizations.

Surgical Intervention is Associated with Improved Outcomes in Patients with Symptomatic Cervical Spine Tarlov Cysts: Results from a Prospective Cohort Study.

BACKGROUND: Tarlov cysts are known contributors to radiculopathy but are often misdiagnosed and mismanaged due to a paucity of information. This is particularly true of cervical spine Tarlov cysts because most attention has been focused on sacral cysts. In this study, we describe our longitudinal experience with patients who underwent surgery for cervical spine Tarlov cysts. We hypothesized that patients undergoing surgical treatment for cervical spine Tarlov cysts would report improvement following surgery. METHODS: We conducted a prospective study of patients who underwent surgical treatment for cervical Tarlov cysts between 2010 and 2021. The Short-Form 36-item survey (SF-36) was administered at the preoperative and follow-up visits. Repeated measures analyses were used to assess changes from preoperatively to postoperatively. RESULTS: A total of 37 patients with cervical spine cysts were included in the study. Follow-up data were available for 27 patients with a median follow-up of 1 year. Of the cohort, 97.3% were women, with an average age of 47.5 ± 10.3 years. Patients reported statistically significant improvement in 2 of the 4 SF-36 physical health domains (physical function, P< 0.001; and bodily pain, P < 0.001) and 2 of the 4 mental health domains (vitality/energy, P < 0.003; and social functioning, P = 0.007). Patients also reported less interference in work, education, and retirement activities at follow-up (P = 0.017). CONCLUSIONS: Our longitudinal series consisted of patients with symptomatic cervical spine Tarlov cysts, which, to the best of our knowledge, is the largest series described. Significant improvements in the SF-36 domains were documented, indicating these patients can be successfully treated surgically.

Surgical Intervention is Associated with Improvement in Health-Related Quality of Life Outcomes in Patients with Symptomatic Sacral Tarlov Cysts: Results from a Prospective Longitudinal Cohort Study.

OBJECTIVE: The treatment of symptomatic Tarlov cysts remains a controversial topic within neurosurgery. We describe our experience with patients who underwent surgical intervention for sacral Tarlov cysts at a single institution. General and disease-specific outcome measures were used to assess health-related quality of life. METHODS: Patients who underwent surgical treatment for one or more sacral Tarlov cysts between 2018 and 2021 were included. The Tarlov Cyst Quality of Life (TCQoL), a validated disease-specific measure, was the primary outcome of the study. Secondary outcomes included general outcome measures: 36-Item Short Form Survey, the Oswestry Disability Index, and Visual Analog Scale. Patients were followed at 3, 6, and 12 months postoperatively. Repeated measures analyses were used to assess change from preoperative to 12 months postoperative. RESULTS: Data were obtained from 144 patients who underwent surgery for sacral Tarlov cysts, average age 52.3 ± 11.3 years, 90.3% female. Patients reported significant mean improvement on the TCQoL over time (preoperative 3.2 ± 0.1; 3-month postoperative 2.1 ± 0.1; 6-month 1.9 ± 0.1; 12-month 1.9 ± 0.1; P < 0.001). Patient age and duration of symptoms were not associated with outcome. A total of 82.3% of patients reported improvement on TCQoL. There was not a significant difference in the proportion of patients reporting improvement on TCQoL by cyst size (small 90.9% vs. large 77.9%; P = 0.066). CONCLUSIONS: Our longitudinal series demonstrated patient-reported improvement following surgery for symptomatic sacral Tarlov cysts using a validated disease-specific health-related quality of life scale through 12 months after surgery. Patient age and preoperative duration of symptoms were not correlated with outcome.

Caller identification and characterization of individual humpback whale acoustic behaviour.

Acoustic recording tags provide fine-scale data linking acoustic signalling with individual behaviour; however, when an animal is in a group, it is challenging to tease apart calls of conspecifics and identify which individuals produce each call. This, in turn, prohibits a robust assessment of individual acoustic behaviour including call rates and silent periods, call bout production within and between individuals, and caller location. To overcome this challenge, we simultaneously instrumented small groups of humpback whales on a western North Atlantic feeding ground with sound and movement recording tags. This approach enabled a comparison of the relative amplitude of each call across individuals to infer caller identity for 97% of calls. We recorded variable call rates across individuals (mean = 23 calls/h) and groups (mean = 55 calls/h). Calls were produced throughout dives, and most calls were produced in bouts with short inter-call intervals of 2.2 s. Most calls received a likely response from a conspecific within 100 s. This caller identification (ID) method facilitates studying both individual- and group-level acoustic behaviour, yielding novel results about the nature of sequence production and vocal exchanges in humpback whale social calls. Future studies can expand on these caller ID methods for understanding intra-group communication across taxa.

Acoustic behavior of humpback whale calves on the feeding ground: Comparisons across age and implications for vocal development.

Studying sound production at different developmental stages can provide insight into the processes involved in vocal ontogeny. Humpback whales (Megaptera novaeangliae) are a known vocal learning species, but their vocal development is poorly understood. While studies of humpback whale calves in the early stages of their lives on the breeding grounds and migration routes exist, little is known about the behavior of these immature, dependent animals by the time they reach the feeding grounds. In this study, we used data from groups of North Atlantic humpback whales in the Gulf of Maine in which all members were simultaneously carrying acoustic recording tags attached with suction cups. This allowed for assignment of likely caller identity using the relative received levels of calls across tags. We analyzed data from 3 calves and 13 adults. There were high levels of call rate variation among these individuals and the results represent preliminary descriptions of calf behavior. Our analysis suggests that, in contrast to the breeding grounds or on migration, calves are no longer acoustically cryptic by the time they reach their feeding ground. Calves and adults both produce calls in bouts, but there may be some differences in bout parameters like inter-call intervals and bout durations. Calves were able to produce most of the adult vocal repertoire but used different call types in different proportions. Finally, we found evidence of immature call types in calves, akin to protosyllables used in babbling in other mammals, including humans. Overall, the sound production of humpback whale calves on the feeding grounds appears to be already similar to that of adults, but with differences in line with ontogenetic changes observed in other vocal learning species.

Deployment of biologging tags on free swimming large whales using uncrewed aerial systems.

Suction-cup-attached biologging tags have led to major advances in our understanding of large whale behaviour. Getting close enough to a whale at sea to safely attach a tag is a major limiting factor when deploying these systems. Here we present an uncrewed aerial system (UAS)-based tagging technique for free-swimming large whales and provide data on efficacy from field testing on blue (Balaenoptera musculus) and fin (B. physalus) whales. Rapid transit speed and the bird's-eye view of the animal during UAS tagging contributed to the technique's success. During 8 days of field testing, we had 29 occasions when a focal animal was identified for attempted tagging and tags were successfully attached 21 times. The technique was efficient, with mean flight time of 2 min 45 s from launch to deployment and a mean distance of 490 m from the launch vessel to tagged animal, reducing potential adverse effects resulting from close approaches for tagging. These data indicate that UAS are capable of attaching biologging tags to free-swimming large whales quickly and from large distances, potentially increasing success rates, decreasing attempt times, and reducing animal disruption during tagging.