The common murre (Uria aalge), an auk seabird, reacts to underwater sound

Author Posting. © Acoustical Society of America, 2020. This article is posted here by permission of Acoustical Society of America for personal use, not for redistribution. The definitive version was published in Journal of the Acoustical Society of America 147(6), (2020): 4069, doi:10.1121/10.0001400.Marine mammals have fine-tuned hearing abilities, which makes them vulnerable to human-induced sounds from shipping, sonars, pile drivers, and air guns. Many species of marine birds, such as penguins, auks, and cormorants, find their food underwater where light is often limited, suggesting sound detection may play a vital role. Yet, for most marine birds, it is unknown whether they are using, and can thereby be affected by, underwater sound. The authors conducted a series of playback experiments to test whether Alcid seabirds responded to and were disrupted by, underwater sound. Underwater broadband sound bursts and mid-frequency naval 53 C sonar signals were presented to two common murres (Uria aalge) in a quiet pool. The received sound pressure levels varied from 110 to 137 dB re 1 μPa. Both murres showed consistent reactions to sounds of all intensities, as compared to no reactions during control trials. For one of the birds, there was a clearly graded response, so that more responses were found at higher received levels. The authors' findings indicate that common murres may be affected by, and therefore potentially also vulnerable to, underwater noise. The effect of man-made noise on murres, and possibly other marine birds, requires more thorough consideration.This project was funded by the U. S. Navy's Living Marine Resources Program (BAA N39433015R7203) and Woods Hole Oceanographic Institution. Birds were loaned from Copenhagen Zoo. Work was conducted under permission from the WHOI Institutional Animal Care and Use Committee, and animal permit to University of Southern Denmark No. 2300-50120-00003-09 from the Danish Ministry of Food and Agriculture. Statistical analysis was assisted by Simeon Smeele (MPI Konstanz, Germany) and Owen Jones (University of Southern Denmark).2020-12-2

A field study of auditory sensitivity of the Atlantic puffin, Fratercula Arctica

Author Posting. © Company of Biologists, 2020. This article is posted here by permission of Company of Biologists for personal use, not for redistribution. The definitive version was published in Journal of Experimental Biology (2020): jeb.228270, doi:10.1242/jeb.228270.Hearing is vital for birds as they rely on acoustic communication with parents, mates, chicks, and conspecifics. Amphibious seabirds face many ecological pressures, having to sense cues in air and underwater. Natural noise conditions have helped shape this sensory modality but anthropogenic noise is increasingly impacting seabirds. Surprisingly little is known about their hearing, despite their imperiled status. Understanding sound sensitivity is vital when we seek to manage manmade noise impacts. We measured the auditory sensitivity of nine wild Atlantic puffins, Fratercula arctica, in a capture-and-release setting in an effort to define their audiogram and compare these data to the hearing of other birds and natural rookery noise. Auditory sensitivity was tested using auditory evoked potential (AEP) methods. Responses were detected from 0.5 to 6 kHz. Mean thresholds were below 40 dB re 20 µPa from 0.75 to 3 kHz indicating that these were the most sensitive auditory frequencies, similar to other seabirds. Thresholds in the ‘middle’ frequency range 1-2.5 kHz were often down to 10-20 dB re 20 µPa. Lowest thresholds were typically at 2.5 kHz. These are the first in-air auditory sensitivity data from multiple wild-caught individuals of a deep-diving Alcid seabird. The audiogram was comparable to other birds of similar size, thereby indicating that puffins have fully functioning aerial hearing despite the constraints of their deep-diving, amphibious lifestyles. There was some variation in thresholds, yet animals generally had sensitive ears suggesting aerial hearing is an important sensory modality for this taxon.This work was supported by the U.S. Navy’s Living Marine Resources Program and the Woods Hole Oceanographic Institution.2021-06-1

Decrease Stress; Train Your Animals: The Effect of Handling Methods on Cortisol Levels in Harbour Porpoises (Phocoena phocoena) Under Human Care

Circulating cortisol levels are accepted as a sensitive indicator of acute stress in marine mammals, particularly in relation with capture and handling. The present study provides the first long-term monitoring of cortisol levels in four harbour porpoises held in human care—an adult male and adult female and two juvenile females. It also compares levels in blood obtained after removing the animal from the water (OWR sampling) with levels in blood obtained at poolside under voluntary husbandry behaviours (VHB sampling). Cortisol levels differed significantly between the four porpoises, although they all exhibited quite high variations in cortisol levels, with averages of 64.9 and 70.5 μg/l in the adult male and female, respectively, and 90.7 and 51.4 μg/l in the juvenile females. OWR sampling induced significantly higher cortisol levels than VHB sampling, with a dramatic threefold decrease in circulating cortisol levels obtained under VHB sampling compared to levels obtained under OWR sampling (16.6 and 20.2 μg/l compared with 64.9 and 70.5 μg/l in the adult male and female respectively). Even if the porpoises showed some habituation to handling, regular and frequent handling over several years did not suppress a significant stress response in the porpoises when they were removed from the water, pointing to the advantage of using VHB for limiting stress in husbandry practices

Determination of growth, mass, and body mass index of harbour porpoises (Phocoena phocoena): Implications for conservational status assessment of populations

Longitudinal data on individual growth and seasonal changes in body mass, girth, and blubber thickness are rarely available for cetaceans, making it difficult to assess their population composition and individual nutritional condition. During different time intervals from 1997 to 2020, we collected longitudinal data on length, body mass, girth,and blubber thickness from seventeen harbour porpoises (Phocoena phocoena) in human care. We compared Gompertz and von Bertalanffy growth curves to collected length data at age 0–4 years for five individuals with known dates of birth. Von Bertalanffy had the lowest AICc value and was used to predict the birth year of twelve animals which age had previously been estimated based on tooth ring analysis and ossification of flipper bones. The growth curve was accurate within 1 yr. of age estimates. Within the first year, the calves grew 66%, attaining 84% of their adult length, and reached asymptotic length at age 3–4. For adults, there were large seasonal variations in body mass, body mass index, girth, and blubber thickness, with up to 28% of variation in body mass between seasons. We predicted individual body mass within ± 2 kg using measurements of length and girth, allowing estimation of body mass index of individuals with unknown mass. Our findings enable monitoring and assessments of population composition as well as nutritional condition of individual harbour porpoises, which is crucial for assessing conservational status and guiding management

In-air hearing of the great cormorant (Phalacrocorax carbo)

Many aquatic birds use sounds extensively for in-air communication. Regardless of this, we know very little about their hearing abilities. The in-air audiogram of a male adult great cormorant (Phalacrocorax carbo) was determined using psychophysical methods (method of constants). Hearing thresholds were derived using pure tones of five different frequencies. The lowest threshold was at 2 kHz: 18 dB re 20 µPa rms. Thresholds derived using signal detection theory were within 2 dB of the ones derived using classical psychophysics. The great cormorant is more sensitive to in-air sounds than previously believed and its hearing abilities are comparable to several other species of birds of similar size. This knowledge is important for our understanding of the hearing abilities of other species of sea birds. It can also be used to develop cormorant deterrent devices for fisheries, as well as to assess the impact of increasing in-air anthropogenic noise levels on cormorants and other aquatic birds

Field-based hearing measurements of two seabird species

Author Posting. © Company of Biologists, 2019. This article is posted here by permission of Company of Biologists for personal use, not for redistribution. The definitive version was published in Journal of Experimental Biology 222 (2019): jeb190710. doi:10.1242/jeb.190710.Hearing is a primary sensory modality for birds. For seabirds, auditory data is challenging to obtain and hearing data are limited. Here, we present methods to measure seabird hearing in the field, using two Alcid species: the common murre Uria aalge and the Atlantic puffin Fratercula arctica. Tests were conducted in a portable semi-anechoic crate using physiological auditory evoked potential (AEP) methods. The crate and AEP system were easily transportable to northern Iceland field sites, where wild birds were caught, sedated, studied and released. The resulting data demonstrate the feasibility of a field-based application of an established neurophysiology method, acquiring high quality avian hearing data in a relatively quiet setting. Similar field methods could be applied to other seabirds, and other bird species, resulting in reliable hearing data from a large number of individuals with a modest field effort. The results will provide insights into the sound sensitivity of species facing acoustic habitat degradation.This work was supported by the U.S. Navy's Living Marine Resources Program and the Woods Hole Oceanographic Institution.2020-01-0

Haematology and clinical blood chemistry in harbour porpoises (Phocoena phocoena) from the inner Danish waters

Harbour porpoises (Phocoena phocoena) in the Baltic Sea are under increasing pressure from anthropogenic activities, which affect the overall health of populations. Individuals’ haematologic and biochemistry parameters are known to be linked to a population’s health status and are therefore useful tools for cross-population comparisons and to assess health patterns of a population through time. However, it is often difficult to acquire data representing the full range of values and assess the influence of intrinsic and extrinsic factors. Here, we present the range of haematology and blood chemistry values obtained from 46 wild (n = 54 blood samples) individuals incidentally caught in pound-nets and five porpoises in long-term human care (n = 449 blood samples) from an outdoor semi-open facility in Denmark. Although it was not possible to formally test the differences between samples from free-ranging and captive individuals, lymphocyte values were lower for free-ranging animals whereas eosinophils and white blood cell values were higher in captive individuals. Aspartate aminotransferase and alanin aminotransferase values were also lower for captive individuals compared to free-ranging ones. Age group did not influence any of the blood parameters tested for free-ranging individuals. Sodium values were higher for males compared to females. Values were higher and lower in the fall for platelets and lactic acid dehydrogenase, respectively, compared to the other seasons. Based on samples yielded by individuals in long-term human care, haemoglobin, mean cell volume, white blood cells, absolute lymphocyte count, and alkaline phosphatase values were all influenced by health status based on clinical examination. These are therefore candidate parameters to assess health status of wild porpoises. Our results underline that it is essential to obtain ranges of reference values for all haematologic and biochemistry markers in order to assess health status of free-ranging individuals. Individuals in human care provide the opportunity to observe biological and ecological determinates (e.g. age, season) of long-term biomarker response patterns and to assess the suite of biomarkers best suited to predict individual health status

The Self-Stranding Behavior of a Killer Whale (<i>Orcinus orca</i>) in Inner Danish Waters and Considerations concerning Human Interference in Live Strandings

The rescue attempts of stranded whales and euthanasia considerations must include condition assessments of the individual involved, but this is challenged by our insufficient knowledge about the health statuses of these whales. Here, we describe three separate strandings of a young male killer whale (Orcinus orca) in shallow Danish waters during 2021–2022. During the first two stranding events, the whale exhibited remarkable behavior and, after refloating attempts and several kilometers of swimming, it returned to shallow water. This suggests that it actively chose to be in this shallow water, perhaps to ensure free airways and respiration. During the last stranding, it stayed in shallow water for 30 days, during which, euthanasia was considered due to its seemingly worsened condition, including a collapsed dorsal fin. However, suddenly, the whale swam away and, a year later, he was seen alive, confirming that euthanasia would have been the wrong decision. This case raises an important question as to when and under what circumstances active human interventions, such as refloating attempts, should be launched and when euthanasia should be carried out. Every stranding is unique and decisions should be based on thorough considerations of the animal’s health and the chance of a successful rescue