Using Predicted Patterns of 3D Prey Distribution to Map King Penguin Foraging Habitat

King penguins (Aptenodytes patagonicus) are an iconic Southern Ocean species, but the prey distributions that underpin their at-sea foraging tracks and diving behaviour remain unclear. We conducted simultaneous acoustic surveys off South Georgia and tracking of king penguins breeding ashore there in Austral summer 2017 to gain insight into habitat use and foraging behaviour. Acoustic surveys revealed ubiquitous deep scattering layers (DSLs; acoustically detected layers of fish and other micronekton that inhabit the mesopelagic zone) at c. 500 m and shallower ephemeral fish schools. Based on DNA extracted from penguin faecal samples, these schools were likely comprised of lanternfish (an important component of king penguin diets), icefish (Channichthyidae spp.) and painted noties (Lepidonotothen larseni). Penguins did not dive as deep as DSLs, but their prey-encounter depth-distributions, as revealed by biologging, overlapped at fine scale (10s of m) with depths of acoustically detected fish schools. We used neural networks to predict local scale (10 km) fish echo intensity and depth distribution at penguin dive locations based on environmental correlates, and developed models of habitat use. Habitat modelling revealed that king penguins preferentially foraged at locations predicted to have shallow and dense (high acoustic energy) fish schools associated with shallow and dense DSLs. These associations could be used to predict the distribution of king penguins from other colonies at South Georgia for which no tracking data are available, and to identify areas of potential ecological significance within the South Georgia and the South Sandwich Islands marine protected area.

The history of hydroacoustic surveys on small pelagic fishes in the European Mediterranean Sea

The study of small pelagic fish by hydroacoustic methods in the Mediterranean Sea began in the Adriatic in the 1950’s. Since 2009, internationally coordinated, extensive, regular surveys have been conducted in the framework of the MEDIAS - Mediterranean International Acoustic Surveys – action, under the EU Data Collection Framework, to provide inputs for the management of small pelagics, particularly European anchovy (Engraulis encrasicolus) and European sardine (Sardina pilchardus). The surveys cover EU Mediterranean waters and monitor the distribution and abundance of small pelagic species using a common protocol. The hydroacoustic surveys, historically conducted by each Country separately, have since been standardized and harmonized. This is a review of the evolution of the surveys from the beginning up to the present and discusses the future prospects. It reports the historical time series of anchovy, sardine and other small pelagics in different areas and describes the spatial and temporal distribution of small pelagic species in decadal maps of the major areas of their distribution in the European Mediterranean Sea. Furthermore, it discusses the use of MEDIAS data for stock assessment purposes, the collection of auxiliary information for an ecosystem-based management approach, the need for further standardization and future challenges.

Pooling and Comparing Noise Annoyance Scores and “High Annoyance” (HA) Responses on the 5-Point and 11-Point Scales: Principles and Practical Advice

The use of different noise annoyance scales across studies and socio-acoustic surveys, in particular the popular 5-point verbal and 11-point numerical scales, has made the evaluation, comparison, and pooling of noise annoyance responses among studies a taxing issue. This is particularly the case when “high annoyance” (HA) responses need to be compared and when the original studies used different scales; thus, there are different so-called cutoff points that define the part of the scale that indicates the HA status. This paper provides practical guidance on pooling and comparing the respective annoyance data in both the linear and logistic regression context in a statistically adequate manner. It caters to researchers who want to carry out pooled analyses on annoyance data that have been collected on different scales or need to compare exposure–HA relationships between the 5-point and 11-point scales. The necessary simulation of a cutoff point non-native to an original scale can be achieved with a random assignment approach, which is exemplified in the paper using original response data from a range of recent noise annoyance surveys. A code example in the R language is provided for easy implementation of the pertinent procedures with one’s own survey data. Lastly, the not insignificant limitations of combining and/or comparing responses from different noise annoyance scales are discussed.

Record of bats and their echolocation calls from southern Dolakha, central Nepal

With 52 species, bats make up almost a quarter of all the mammal species in Nepal, and yet remains the least understudied group of mammals. Owing to its diverse geography and climate, more species of bats potentially occur in the country, and acoustic surveys could improve the knowledge of their ecology. So, a study was conducted in Sailung and Melung Rural Municipalities of Dolakha district of Nepal, with the objectives of assessing bat species richness and preparing digital records of their echolocation calls. Using mist-netting and roost survey during three periods in 2018 (late March, late May to early June and mid-November), 10 species of bats were recorded: Cynopterus sphinx, Lyroderma lyra, Rhinolophus ferrumequinum, Rhinolophus luctus, Rhinolophus pearsonii, Rhinolophus sinicus, Hipposideros armiger, Myotis formosus, Myotis sp. and Nyctalus noctula. Ten roosts (mostly caves) were located. Echolocation calls of six of these species were documented, including signals of three species described for the first time in Nepal. This study also reports the fifth record of Myotis formosus in Nepal and new locality record of the species after two decades. The echolocation calls documented hereafter may serve as a reference for species identification for non-invasive studies of bats.

The Effect of an Alternative Definition of “Percent Highly Annoyed” on the Exposure–Response Relationship: Comparison of Noise Annoyance Responses Measured by ICBEN 5-Point Verbal and 11-Point Numerical Scales

Since the development of the 5-point verbal and 11-point numerical scales for measuring noise annoyance by the ICBEN Team 6, these scales have been widely used in socio-acoustic surveys worldwide, and annoyance responses have been easily compared internationally. However, both the top two categories of the 5–point verbal scale and the top three ones of the 11-point numerical scale are correspond to high annoyance, so it is difficult to precisely compare annoyance responses. Therefore, we calculated differences in day–evening–night-weighted sound pressure levels (Lden) by comparing values corresponding to 10% highly annoyed (HA) on Lden_%HA curves obtained from measurements in 40 datasets regarding surveys conducted in Japan and Vietnam. The results showed that the Lden value corresponding to 10% HA using the 5-point verbal scale was approximately 5 dB lower than that of the 11-point numerical scale. Thus, some correction is required to compare annoyance responses measured by the 5-point verbal and the 11-point numerical scales. The results of this study were also compared with those of a survey in Switzerland.