Miller Patrick J. O.

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Miller

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Patrick J. O.

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Ascent exhalations of Antarctic fur seals : a behavioural adaptation for breath-hold diving?

(Royal Society, 2005-02-22) Hooker, Sascha K. ; Miller, Patrick J. O. ; Johnson, Mark P. ; Cox, Oliver P. ; Boyd, Ian L.

Novel observations collected from video, acoustic and conductivity sensors showed that Antarctic fur seals consistently exhale during the last 50–85% of ascent from all dives (10–160 m, n > 8000 dives from 50 seals). The depth of initial bubble emission was best predicted by maximum dive depth, suggesting an underlying physical mechanism. Bubble sound intensity recorded from one seal followed predictions of a simple model based on venting expanding lung air with decreasing pressure. Comparison of air release between dives, together with lack of variation in intensity of thrusting movement during initial descent regardless of ultimate dive depth, suggested that inhaled diving lung volume was constant for all dives. The thrusting intensity in the final phase of ascent was greater for dives in which ascent exhalation began at a greater depth, suggesting an energetic cost to this behaviour, probably as a result of loss of buoyancy from reduced lung volume. These results suggest that fur seals descend with full lung air stores, and thus face the physiological consequences of pressure at depth. We suggest that these regular and predictable ascent exhalations could function to reduce the potential for a precipitous drop in blood oxygen that would result in shallow-water blackout.
Caller sex and orientation influence spectral characteristics of “two-voice” stereotyped calls produced by free-ranging killer whales

(Acoustical Society of America, 2007-06) Miller, Patrick J. O. ; Samarra, Filipa I. P. ; Perthuison, Aurelie D.

This study investigates how particular received spectral characteristics of stereotyped calls of sexually dimorphic adult killer whales may be influenced by caller sex, orientation, and range. Calls were ascribed to individuals during natural behavior using a towed beamforming array. The fundamental frequency of both high-frequency and low-frequency components did not differ consistently by sex. The ratio of peak energy within the fundamental of the high-frequency component relative to summed peak energy in the first two low-frequency component harmonics, and the number of modulation bands off the high-frequency component, were significantly greater when whales were oriented towards the array, while range and adult sex had little effect. In contrast, the ratio of peak energy in the first versus second harmonics of the low-frequency component was greater in calls produced by adult females than adult males, while orientation and range had little effect. The dispersion of energy across harmonics has been shown to relate to body size or sex in terrestrial species, but pressure effects during diving are thought to make such a signal unreliable in diving animals. The observed spectral differences by signaler sex and orientation suggest that these types of information may be transmitted acoustically by freely diving killer whales.
Diversity in sound pressure levels and estimated active space of resident killer whale vocalizations

( 2005-12-02) Miller, Patrick J. O.

Signal source intensity and detection range, which integrates source intensity with propagation loss, background noise and receiver hearing abilities, are important characteristics of communication signals. Apparent source levels were calculated for 819 pulsed calls and 24 whistles produced by free-ranging resident killer whales by triangulating the angles-of-arrival of sounds on two beamforming arrays towed in series. Levels in the 1-20 kHz band ranged from 131-168 dB re 1μPa @1m, with differences in the means of different sound classes (whistles: 140.2 ± 4.1 dB; variable calls: 146.6 ± 6.6 dB; stereotyped calls: 152.6 ± 5.9 dB), and among stereotyped call types. Repertoire diversity carried through to estimates of active space, with “long-range” stereotyped calls all containing overlapping, independently-modulated high-frequency components (mean estimated active space of 10-16km in sea state zero) and “short-range” sounds (5-9 km) included all stereotyped calls without a high-frequency component, whistles, and variable calls. Short-range sounds are reported to be more common during social and resting behaviors, while long-range stereotyped calls predominate in dispersed travel and foraging behaviors. These results suggest that variability in sound pressure levels may reflect diverse social and ecological functions of the acoustic repertoire of killer whales.
Understanding the combined effects of multiple stressors: a new perspective on a longstanding challenge

(Elsevier, 2022-01-29) Pirotta, Enrico ; Thomas, Len ; Costa, Daniel P. ; Hall, Ailsa J. ; Harris, Catriona M. ; Harwood, John ; Kraus, Scott D. ; Miller, Patrick J. O. ; Moore, Michael J. ; Photopoulou, Theoni ; Rolland, Rosalind M. ; Schwacke, Lori ; Simmons, Samantha E. ; Southall, Brandon L. ; Tyack, Peter L.

Wildlife populations and their habitats are exposed to an expanding diversity and intensity of stressors caused by human activities, within the broader context of natural processes and increasing pressure from climate change. Estimating how these multiple stressors affect individuals, populations, and ecosystems is thus of growing importance. However, their combined effects often cannot be predicted reliably from the individual effects of each stressor, and we lack the mechanistic understanding and analytical tools to predict their joint outcomes. We review the science of multiple stressors and present a conceptual framework that captures and reconciles the variety of existing approaches for assessing combined effects. Specifically, we show that all approaches lie along a spectrum, reflecting increasing assumptions about the mechanisms that regulate the action of single stressors and their combined effects. An emphasis on mechanisms improves analytical precision and predictive power but could introduce bias if the underlying assumptions are incorrect. A purely empirical approach has less risk of bias but requires adequate data on the effects of the full range of anticipated combinations of stressor types and magnitudes. We illustrate how this spectrum can be formalised into specific analytical methods, using an example of North Atlantic right whales feeding on limited prey resources while simultaneously being affected by entanglement in fishing gear. In practice, case-specific management needs and data availability will guide the exploration of the stressor combinations of interest and the selection of a suitable trade-off between precision and bias. We argue that the primary goal for adaptive management should be to identify the most practical and effective ways to remove or reduce specific combinations of stressors, bringing the risk of adverse impacts on populations and ecosystems below acceptable thresholds.
Equipment to tag, track and collect biopsies from whales and dolphins: the ARTS, DFHorten and LKDart systems

(BioMed Central, 2022-10-21) Kleivane, Lars ; Kvadsheim, Petter H. ; Bocconcelli, Alex ; Øien, Nils ; Miller, Patrick J. O.

Of all animals considered subjects for instrumentation for behavioral or physiological studies, cetaceans probably represent the greatest challenge to the engineer and biologist. The marine environment being harsh to electronics, evasive behavior during tagging approaches and the short time window available to attach instruments, all imply a need for innovative tagging solutions to facilitate better understanding of their life cycle, migration, physiology, behavior, health and genetics. Several animal-attached tag packages holding specific data loggers, e.g., time depth recorders, position, orientation, acoustic and video recorders for short to medium term studies, as well as tags developed for large scale migration telemetry studies are available as off-the-shelf devices, or in many cases as custom made sensor packages. Deployment of those instruments is often the limiting factor for data collection. The Aerial Remote Tag System (ARTS) is a flexible system which can easily be adapted to deploy different tag sensor packages and biopsy collection devices. This paper presents the history and design of the ARTS, and accessories developed for instrumentation and biopsy sampling of cetaceans, such as the recent developed ARTS–LKDart for biopsy sampling. Deployment of archival tags usually requires radio tracking of the instrumented animal, or at least tracking of the tag for recovery. Thus, we also here describe the automatic digital signal processing radio direction finder, the Direction Finder Horten (DFHorten unit).
Premilinary results of the effects of SURTASS-LFA sonar on singing humpback whales

(Woods Hole Oceanographic Institution, 2000-05) Biassoni, Nicoletta ; Miller, Patrick J. O. ; Tyack, Peter L.

The singing behavior of humpback whales exposed to SURTASS-LFA sonar was monitored in Hawaii during March 1998. An observation vessel towing a hydrophone array followed individual singers continuously recording their songs and the received level of sonar near the whale. At least 2 complete songs were recorded before commencing a 60min 42s long playback, which consisted of ten 42s signals transmitted every 6 min. by a U.S. Navy vessel. Observations continued into the post-exposure period. Song spectrograms were broken into themes and phrases using visual analysis and aurol scoring. 23 focal follows were conducted; 5 were control follows with no playback. In 9 follows the whale sang throughout the playback, in 4 the whale stopped singing when it joined another whale and in 5 it stopped presumably in response to the playback. We recorded at least one complete song in all three experimental conditions from six individuals. These singers sang longer sonsgs during (13.75min) than before (10.68min) or after (10.58min) the playback (model III ANOVA, p=0.047, n=6). No differences were found in theme order. Song cessation and song duration responses did not scale with sonar received level. High variability in individual responses may indicate that some males were more sensitive to the sonar than others.
Changes in dive behavior during naval sonar exposure in killer whales, long-finned pilot whales, and sperm whales

(Frontiers Media, 2012-10-11) Sivle, L. D. ; Kvadsheim, P. H. ; Fahlman, Andreas ; Lam, F. P. A. ; Tyack, Peter L. ; Miller, Patrick J. O.

Anthropogenic underwater sound in the environment might potentially affect the behavior of marine mammals enough to have an impact on their reproduction and survival. Diving behavior of four killer whales (Orcinus orca), seven long-finned pilot whales (Globicephala melas), and four sperm whales (Physeter macrocephalus) was studied during controlled exposures to naval sonar [low frequency active sonar (LFAS): 1–2 kHz and mid frequency active sonar (MFAS): 6–7 kHz] during three field seasons (2006–2009). Diving behavior was monitored before, during and after sonar exposure using an archival tag placed on the animal with suction cups. The tag recorded the animal's vertical movement, and additional data on horizontal movement and vocalizations were used to determine behavioral modes. Killer whales that were conducting deep dives at sonar onset changed abruptly to shallow diving (ShD) during LFAS, while killer whales conducting deep dives at the onset of MFAS did not alter dive mode. When in ShD mode at sonar onset, killer whales did not change their diving behavior. Pilot and sperm whales performed normal deep dives (NDD) during MFAS exposure. During LFAS exposures, long-finned pilot whales mostly performed fewer deep dives and some sperm whales performed shallower and shorter dives. Acoustic recording data presented previously indicates that deep diving (DD) is associated with feeding. Therefore, the observed changes in dive behavior of the three species could potentially reduce the foraging efficiency of the affected animals.
Estimated tissue and blood N2 levels and risk of decompression sickness in deep-, intermediate-, and shallow-diving toothed whales during exposure to naval sonar

(Frontiers Media, 2012-05-10) Kvadsheim, P. H. ; Miller, Patrick J. O. ; Tyack, Peter L. ; Sivle, L. D. ; Lam, F. P. A. ; Fahlman, Andreas

Naval sonar has been accused of causing whale stranding by a mechanism which increases formation of tissue N2 gas bubbles. Increased tissue and blood N2 levels, and thereby increased risk of decompression sickness (DCS), is thought to result from changes in behavior or physiological responses during diving. Previous theoretical studies have used hypothetical sonar-induced changes in both behavior and physiology to model blood and tissue N2 tension (PN2), but this is the first attempt to estimate the changes during actual behavioral responses to sonar. We used an existing mathematical model to estimate blood and tissue N2 tension (PN2) from dive data recorded from sperm, killer, long-finned pilot, Blainville’s beaked, and Cuvier’s beaked whales before and during exposure to Low- (1–2 kHz) and Mid- (2–7 kHz) frequency active sonar. Our objectives were: (1) to determine if differences in dive behavior affects risk of bubble formation, and if (2) behavioral- or (3) physiological responses to sonar are plausible risk factors. Our results suggest that all species have natural high N2 levels, with deep diving generally resulting in higher end-dive PN2 as compared with shallow diving. Sonar exposure caused some changes in dive behavior in both killer whales, pilot whales and beaked whales, but this did not lead to any increased risk of DCS. However, in three of eight exposure session with sperm whales, the animal changed to shallower diving, and in all these cases this seem to result in an increased risk of DCS, although risk was still within the normal risk range of this species. When a hypothetical removal of the normal dive response (bradycardia and peripheral vasoconstriction), was added to the behavioral response during model simulations, this led to an increased variance in the estimated end-dive N2 levels, but no consistent change of risk. In conclusion, we cannot rule out the possibility that a combination of behavioral and physiological responses to sonar have the potential to alter the blood and tissue end-dive N2 tension to levels which could cause DCS and formation of in vivo bubbles, but the actually observed behavioral responses of cetaceans to sonar in our study, do not imply any significantly increased risk of DCS.
Modeling acoustic propagation of airgun array pulses recorded on tagged sperm whales (Physeter macrocephalus)

(Acoustical Society of America, 2006-12) DeRuiter, Stacy L. ; Tyack, Peter L. ; Lin, Ying-Tsong ; Newhall, Arthur E. ; Lynch, James F. ; Miller, Patrick J. O.

In 2002 and 2003, tagged sperm whales (Physeter macrocephalus) were experimentally exposed to airgun pulses in the Gulf of Mexico, with the tags providing acoustic recordings at measured ranges and depths. Ray trace and parabolic equation (PE) models provided information about sound propagation paths and accurately predicted time of arrival differences between multipath arrivals. With adequate environmental information, a broadband acoustic PE model predicted the relative levels of multipath arrivals recorded on the tagged whales. However, lack of array source signature data limited modeling of absolute received levels. Airguns produce energy primarily below 250 Hz, with spectrum levels about 20–40 dB lower at 1 kHz. Some arrivals recorded near the surface in 2002 had energy predominantly above 500 Hz; a surface duct in the 2002 sound speed profile helps explain this effect, and the beampattern of the source array also indicates an increased proportion of high-frequency sound at near-horizontal launch angles. These findings indicate that airguns sometimes expose animals to measurable sound energy above 250 Hz, and demonstrate the influences of source and environmental parameters on characteristics of received airgun pulses. The study also illustrates that on-axis source levels and simple geometric spreading inadequately describe airgun pulse propagation and the extent of exposure zones.
Stroke frequency, but not swimming speed, is related to body size in free-ranging seabirds, pinnipeds and cetaceans

(Royal Society, 2006-12-05) Sato, Katsufumi ; Watanuki, Yutaka ; Takahashi, Akinori ; Miller, Patrick J. O. ; Tanaka, Hideji ; Kawabe, Ryo ; Ponganis, Paul J. ; Handrich, Yves ; Akamatsu, Tomonari ; Watanabe, Yuuki ; Mitani, Yoko ; Costa, Daniel P. ; Bost, Charles-Andre ; Aoki, Kagari ; Amano, Masao ; Trathan, Phil N. ; Shapiro, Ari D. ; Naito, Yasuhiko

It is obvious, at least qualitatively, that small animals move their locomotory apparatus faster than large animals: small insects move their wings invisibly fast, while large birds flap their wings slowly. However, quantitative observations have been difficult to obtain from free-ranging swimming animals. We surveyed the swimming behaviour of animals ranging from 0.5kg seabirds to 30000kg sperm whales using animal-borne accelerometers. Dominant stroke cycle frequencies of swimming specialist seabirds and marine mammals were proportional to mass−0.29 (R2=0.99, n=17 groups), while propulsive swimming speeds of 1–2ms−1 were independent of body size. This scaling relationship, obtained from breath-hold divers expected to swim optimally to conserve oxygen, does not agree with recent theoretical predictions for optimal swimming. Seabirds that use their wings for both swimming and flying stroked at a lower frequency than other swimming specialists of the same size, suggesting a morphological trade-off with wing size and stroke frequency representing a compromise. In contrast, foot-propelled diving birds such as shags had similar stroke frequencies as other swimming specialists. These results suggest that muscle characteristics may constrain swimming during cruising travel, with convergence among diving specialists in the proportions and contraction rates of propulsive muscles.
Maintaining contact : design and use of acoustic signals in killer whales, Orcinus orca

(Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 2000-09) Miller, Patrick J. O.

This thesis presents data on the structure and use of acoustic signals produced by free-ranging resident killer whales. The analysis focuses on signal features that might be useful for animals to maintain contact and coordinate activities with preferred associates, including: distinctiveness by group or individual, call amplitude, and directionality cues that might cue the direction-of-movement of the signaler. Research was conducted in Haro and Johnstone Straits off Vancouver Island, British Columbia, where killer whales have been the focus of a long-term photo-identification effort. Extensive previous research on this population has demonstrated stable kin-based matrilineal social groups and pod-specific calling behavior. Individually-distinctive markings and pigmentation patterns were used to identify groups or individuals from which sounds were recorded. Recordings from each of the three matrilineal groups composing pod Al were made when each subgroup was isolated from the two other subgroups. Analysis of call use and structure revealed subgroup-specificity that was qualitatively similar to previously observed differences between pods, although more subtle. This finding suggests that pod-specific calling arises primarily as a consequence of accumulated drift or divergence of calls between highly cohesive matrilineal subgroups as they gradually separate into different pods. A new towed array beamforming system was developed to identify vocalizing killer whales concurrent with focal behavioral observations. Carefully positioning the array relative to the animals and linking visual observations of whale position with the angle-of-arrival of sounds on the towed array allows reliable identification of signalers in many circumstances. Using this new system, a sample of 140 calls was recorded from identified individuals within W-pod to compare the call-type repertoires of individuals within a matrilineal subgroup. The three individuals composing W-pod shared at least four different call types and call-type frequency did not differ by individual, suggesting each matrilineal group member uses the same call types in a similar fashion. To measure signal source levels, the range from the array to a signaler was calculated by triangulating the angles-of-arrival of the sound on two beamforming arrays towed in series. Source levels of 819 calls and 24 whistles were combined with a model of sound propagation and perception to estimate the maximum range at which another killer whale could detect each sound in quiet conditions. The estimated maximum range of detectability of all sounds ranged from 4.5 to 26.2 km, suggesting killer whales can maintain acoustic contact with each other over long ranges. Whistles and variable calls have a smaller active space than stereotyped calls which appear to consist of two groups: long- and short-range call types with a mean estimated active space of 14.5 and 8.8 km, respectively. Directionality features of calls were described by recording sounds in front of, and behind, groups of animals as they passed the towed-array system. The frequency structure of the sample of 263 calls recorded in these conditions was clearly dependent on the orientation of the signaler to the receiver, with high-frequency components strongly attenuated when the whales were oriented away from the array. This directionality pattern appears to provide a simple and reliable cue of the direction-of-movement of signalers, and may be an important structural feature of calls helping killer whales regulate their spacing relative to each other.
Managing the effects of multiple stressors on wildlife populations in their ecosystems: developing a cumulative risk approach

(The Royal Society, 2022-11-30) Tyack, Peter L. ; Thomas, Len ; Costa, Daniel P. ; Hall, Ailsa J. ; Harris, Catriona M. ; Harwood, John ; Kraus, Scott D. ; Miller, Patrick J. O. ; Moore, Michael ; Photopoulou, Theoni ; Pirotta, Enrico ; Rolland, Rosalind M. ; Schwacke, Lori H. ; Simmons, Samantha E. ; Southall, Brandon L.

Assessing cumulative effects of human activities on ecosystems is required by many jurisdictions, but current science cannot meet regulatory demands. Regulations define them as effect(s) of one human action combined with other actions. Here we argue for an approach that evaluates the cumulative risk of multiple stressors for protected wildlife populations within their ecosystems. Monitoring effects of each stressor is necessary but not sufficient to estimate how multiple stressors interact to affect wildlife populations. Examining the mechanistic pathways, from cellular to ecological, by which stressors affect individuals can help prioritize stressors and interpret how they interact. Our approach uses health indicators to accumulate the effects of stressors on individuals and to estimate changes in vital rates, driving population status. We advocate using methods well-established in human health and integrating them into ecosystem-based management to protect the health of commercially and culturally important wildlife populations and to protect against risk of extinction for threatened species. Our approach will improve abilities to conserve and manage ecosystems but will also demand significant increases in research and monitoring effort. We advocate for increased investment proportional to the economic scale of human activities in the Anthropocene and their pervasive effects on ecology and biodiversity.
Sperm whale behaviour indicates the use of echolocation click buzzes 'creaks' in prey capture

(Royal Society, 2004-10-25) Miller, Patrick J. O. ; Johnson, Mark P. ; Tyack, Peter L.

During foraging dives, sperm whales (Physeter macrocephalus) produce long series of regular clicks at 0.5-2 s intervals interspersed with rapid-click buzzes called 'creaks'. Sound, depth and orientation recording Dtags were attached to 23 whales in the Ligurian Sea and Gulf of Mexico to test whether the behaviour of diving sperm whales supports the hypothesis that creaks are produced during prey capture. Sperm whales spent most of their bottom time within one or two depth bands, apparently feeding in vertically stratified prey layers. Creak rates were highest during the bottom phase: 99.8% of creaks were produced in the deepest 50% of dives, 57% in the deepest 15% of dives. Whales swam actively during the bottom phase, producing a mean of 12.5 depth inflections per dive. A mean of 32% of creaks produced during the bottom phase occurred within 10 s of an inflection (13× more than chance). Sperm whales actively altered their body orientation throughout the bottom phase with significantly increased rates of change during creaks, reflecting increased manoeuvring. Sperm whales increased their bottom foraging time when creak rates were higher. These results all strongly support the hypothesis that creaks are an echolocation signal adapted for foraging, analogous to terminal buzzes in taxonomically diverse echolocating species.

Miller Patrick J. O.

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