Article

Visualization of temporal change in soundscape power of a Michigan lake habitat over a 4-year period

January 2013
Ecological Informatics 21

DOI:10.1016/j.ecoinf.2013.11.004

Project: Soundscape Ecology

Authors:

Stuart H Gage

Michigan State University

Anne C. Axel

Marshall University

Soundscape Ecology is an emerging area of science that does not focus on the identification of species in the soundscape but attempts to characterize sounds by organizing them into those produced by biological organisms such as birds, amphibians, insects or mammals; physical environmental factors such as thunder, rainfall or wind; and sounds produced by human entities such as airplanes, automobiles or air conditioners. The soundscape changes throughout the day and throughout the seasons. The soundscape components that create the sound occur at different frequencies. A set of metrics termed soundscape power was computed and visualized to examine the patterns of daily and seasonal change in the soundscape.

Acoustic Footprint of Snowmobile Noise and Natural Quiet Refugia in an Alaskan Wilderness

Article

Full-text available

Sep 2020
NAT AREA J

Assessing soundscape disturbance through hierarchical models and acoustic indices: A case study on a shelterwood logged northern Michigan forest

Article

Jun 2020
ECOL INDIC

Assessing the effects of anthropogenic disturbances on wildlife and natural resources is a necessary conservation task. The soundscape is a critical habitat component for acoustically communicating organisms, but the use of the soundscape as a tool for assessing disturbance impacts has been relatively unexplored until recently. Here we present a broad modeling framework for assessing disturbance impacts on soundscapes, which we apply to quantify the influence of a shelterwood logging on soundscapes in northern Michigan. Our modeling approach can be broadly applied to assess anthropogenic disturbance impacts on soundscapes. The approach accommodates inherent differences in control and treatment sites to improve inference about treatment effects, while also accounting for extraneous variables (e.g., rain) that influence acoustic indices. Recordings were obtained at 13 sites before and after a shelterwood logging. Four sites were in the logging region and nine sites served as control recordings outside the logging region. We quantify the soundscapes using common acoustic indices (Normalized Difference Soundscape Index (NDSI), Acoustic Entropy (H), Acoustic Complexity Index (ACI), Acoustic Evenness Index (AEI)) and Welch Power Spectral Density (PSD) values. We build two hierarchical Bayesian models to quantify the changes in the soundscape over the study period. Our analysis reveals no long-lasting effects of the shelterwood logging on the soundscape as measured by the NDSI, but analysis of H, AEI, and PSD suggest changes in the evenness of sounds across the frequency spectrum, indicating a potential shift in the avian species communicating in the soundscapes as a result of the logging. Further, our analysis confirms previous findings that the ACI does not accurately reflect changes in landscape configuration. Multiple model validation techniques (i.e., comparison of parameter estimates and the widely applicable information criterion (WAIC)) reveal our proposed hierarchical Bayesian models outperform more simple models used for hypothesis testing. Acoustic recordings, in conjunction with this modeling framework, can deliver cost efficient assessment of disturbance impacts on the landscape and underlying biodiversity as represented through the soundscape.

Ornithophony in the soundscape of Anaikatty Hills, Coimbatore, Tamil Nadu, India

Article

Full-text available

Sep 2019

An attempt has been made to understand the extent of ornithophony (vocalization of birds) in the soundscape of Anaikatty Hills. The study was limited to 13 hours of daylight from dawn to dusk (06.00–19.00 h) between January 2015 and October 2016. Six replicates of 5-minute bird call recordings were collected from each hour window in 24 recording spots of the study area. Each 5-minute recording was divided into 150 ‘2-sec’ observation units for the detailed analysis of the soundscape. A total of 78 recordings amounting to 390 minutes of acoustic data allowed a preliminary analysis of the ornithophony of the area. A total of 62 bird species were heard vocalizing during the study period and contributed 8,629 units. A total of 73.75% acoustic space was occupied by birds, among which the eight dominant species alone contributed to 63.65% of ornithophony. The remaining 26% of acoustic space was occupied by other biophonies (12.60%), geophony (5.57%), indistinct sounds (7.66%), and anthropogenic noise (0.41%). Passerines dominated the vocalizations with 7,269 (84.24%) and non-passerines with 1,360 (15.76%) units. Birds vocalized in all 13 observation windows, with a peak in the first three hours of the day (06.00–09.00 h). Vocalizations of non-passerines were prominent in the dusk hours (18.00–19.00 h).

What does Atlantic Forest soundscapes can tell us about landscape?

Article

Full-text available

Feb 2021

The ecoacoustics approach for environmental recordings analysis is used to understand and identify big ecological patterns related to different sound sources, like animals, humans and the environment itself. Sounds can vary according to several features that can be on its surroundings or far away, therefore they are very much reliant on scale. Because humans are changing the environment so much and we cannot account for all those changes in the same speed as they happen, we need fast evaluation tools, such as remote sensing and acoustic monitoring (considered the equivalent of spatial remote sensing for sounds). Considering that the scale of effect was never measured for soundscapes before, we aimed to see in what scale different acoustic indices were responsive. Also, we tested how acoustic indices are influenced by natural vegetation cover. We recorded environmental sounds in Atlantic Forest fragments during three months on the rainy season. Then we calculated different acoustic indices and the percentage of natural vegetation cover in different scales. Our results corroborated our initial hypotheses: different indices respond to different scales and their medians varied according to the amount of vegetation cover on the surroundings. More studies are needed with less fragmented areas, to test indices behaviour in a continuum, but we consider this work an important starting point to understand acoustic indices behaviour in tropical areas, especially in such degraded and threatened area as Atlantic Forest.

Assessing soundscape disturbance through hierarchical models and acoustic indices: a case study on a shelterwood logged northern Michigan forest

Preprint

Nov 2019

Assessing the effects of anthropogenic disturbances on wildlife is a necessary conservation task. The soundscape is a critical habitat component for acoustically communicating organisms, but the use of the soundscape as a tool for assessing disturbance impacts has been relatively unexplored until recently. Here we present a broad modeling framework for assessing disturbance impacts on soundscapes, which we apply to quantify the influence of a shelterwood logging on soundscapes in northern Michigan. Our modeling approach can be broadly applied to assess anthropogenic disturbance impacts on soundscapes. The approach accommodates inherent differences in control and treatment sites to improve inference about treatment effects, while also accounting for extraneous variables (e.g., rain) that influence acoustic indices. Recordings were obtained at 13 sites before and after a shelterwood logging. Four sites were in the logging region and nine sites served as control recordings outside the logging region. We quantify the soundscapes using common acoustic indices (Normalized Difference Soundscape Index (NDSI), Acoustic Entropy (H), Acoustic Complexity Index (ACI), Acoustic Evenness Index (AEI), Welch Power Spectral Density (PSD)) and build two hierarchical Bayesian models to quantify the changes in the soundscape over the study period. Our analysis reveals no long-lasting effects of the shelterwood logging on the soundscape diversity as measured by the NDSI, but analysis of H, AEI, and PSD suggest changes in the evenness of sounds across the frequency spectrum, indicating a potential shift in the avian species communicating in the soundscapes as a result of the logging. Acoustic recordings, in conjunction with this modeling framework, can deliver cost efficient assessment of disturbance impacts on the landscape and underlying biodiversity as represented through the soundscape.

Soundscapes of urban parks: An innovative approach for ecosystem monitoring and adaptive management

Article

Full-text available

May 2022

Urban foresters are addressing the challenge of urban biodiversity loss through management plans in the context of rapid urbanization. Protecting the integrity of the urban ecosystem requires long-term monitoring and planning for resilience as well as effective management. The soundscape assessment has attracted attention in this field, but applying the soundscape assessment in urban ecological monitoring requires a protocol that links soundscapes to the impact of resource management on biodiversity over time. The effective processing and visualization of large-scale data also remains an important challenge. The aim of this study was to better understand the relationship between soundscape and physical environment, and examine the feasibility of this innovative soundscape approach in highly urbanized areas. Soundscape recordings were collected for 20 urban parks twice on 4 consecutive days in Spring. A total of 691,200 min of sound material were automatically obtained. In order to track the spatio-temporal patterns of a soundscape and determine its potential suitability for ecosystem monitoring, our study characterized soundscape information by adopting 4 widely used acoustic indices: acoustic diversity index (ADI), bioacoustic index (BIO), normalized difference vegetation index (NDSI), and power spectral density (PSD). Daily patterns of PSD have provided a potential connection between soundscapes and bird songs, and 1–2 kHz presented a similar pattern that was linked to human activity. Through further modeling, we tested the relationship of soundscapes to physical environment characteristics. The results showed the importance of habitat vegetation structure for acoustic diversity. More vertical heterogeneity, with an uneven canopy height or multilayered vegetation, was associated with more acoustic diversity. This suggests that clearing ground cover may have a significant negative impact on wildlife. Our results suggest that soundscape approaches provide a way to quickly synthesize large-scale recording data into meaningful patterns that can track changes in bird songs and ecosystem conditions. The proposed approach would enable regular assessment of urban parks and forests to inform adaptive planning and management strategies that can maintain or enhance biodiversity.

Apport de la bioacoustique pour le suivi d’une espèce discrète : le Loup gris (Canis lupus)

Thesis

Nov 2018

Morgane Papin

Le nombre croissant de travaux réalisés ces dernières années a montré que la bioacoustique est particulièrement intéressante pour le suivi d’espèces discrètes. L’émergence de dispositifs d’enregistrement autonomes, associée à de nouvelles méthodes d’analyse, ont récemment participé à l’accroissement des études dans ce domaine. Au cours des 30 dernières années, le Loup gris (Canis lupus), mammifère carnivore aux mœurs discrètes connu pour ses hurlements de longue portée, a fait l’objet de nombreuses études acoustiques. Ces dernières visaient notamment à améliorer son suivi, qui s’avère complexe du fait des grandes capacités de déplacement des loups, de l’étendue de leurs territoires et de la diversité des milieux dans lesquels ils vivent. Cependant, la bioacoustique passive a jusqu’alors très peu été exploitée pour le suivi du Loup. C’est dans ce contexte que la présente thèse s’est organisée autour de trois axes de recherche. Les deux premiers axes portent sur l’apport de la bioacoustique passive pour le suivi du Loup gris en milieu naturel. En combinant des analyses acoustiques, statistiques et cartographiques, le premier objectif a été d’élaborer une méthode pour l’échantillonnage spatial de vastes zones d’étude, afin d’y détecter des hurlements de loups à l’aide de réseaux d’enregistreurs autonomes. Ce même dispositif a ensuite permis, dans un second temps, de tester la possibilité de localiser les loups grâce à leurs hurlements. Les expérimentations conduites en milieu de moyenne montagne (Massif des Vosges) et de plaine (Côtes de Meuse), sur deux zones d’étude de 30 km² et avec un réseau de 20 enregistreurs autonomes, ont permis de démontrer l’intérêt de la bioacoustique passive pour le suivi du Loup gris. En effet, près de 70% des émissions sonores (son synthétique aux propriétés similaires à celles de hurlements de loups) ont été détectés par au moins un enregistreur autonome en milieu de moyenne montagne et plus de 80% en milieu de plaine, pour des distances enregistreurs– source sonore atteignant respectivement plus de 2.7 km et plus de 3.5 km. Grâce à un modèle statistique et à un Système d’Information Géographique, la probabilité de détection des hurlements a pu être cartographiée sur les deux zones. En moyenne montagne, elle était forte à très forte (>0.5) sur 5.72 km² de la zone d’étude, contre 21.43 km² en milieu de plaine. Les sites d’émission ont été localisés avec une précision moyenne de 315 ± 617 (SD) m, réduite à 167 ± 308 (SD) m après l’application d’un seuil d’erreur temporelle défini d’après la distribution des données. Le troisième axe de travail porte quant à lui sur l’application d’indices de diversité acoustique pour estimer le nombre d’individus participant à un chorus et ainsi contribuer au suivi de l’effectif des meutes. Les valeurs obtenues pour les six indices (H, Ht, Hf, AR, M et ACI) étaient corrélées avec le nombre de loups hurlant dans les chorus artificiels testés. De bonnes prédictions de l’effectif ont été obtenues sur des chorus réels avec l’un de ces indices (ACI). L’influence de plusieurs biais sur la précision des prédictions de chacun des six indices a ensuite pu être étudiée, montrant que trois d’entre eux y étaient relativement peu sensibles (Hf, AR et ACI). Finalement, les résultats obtenus avec les enregistreurs autonomes montrent le potentiel des méthodes acoustiques passives pour la détection de la présence de loups mais aussi pour les localiser avec une bonne précision, dans des milieux contrastés et à de larges échelles spatiale et temporelle. L’utilisation des indices de diversité acoustique ouvre également de nouvelles perspectives pour l’estimation de l’effectif des meutes. Prometteuses, l’ensemble des méthodes émergeant de ce travail nécessite à présent quelques investigations complémentaires avant d’envisager une application concrète pour le suivi du Loup gris dans son milieu naturel.

An Ecoacoustic Snapshot of a Subarctic Coastal Wilderness: Aialik Bay, Alaska 2019

Article

Full-text available

Jan 2022

Timothy Mullet

I recorded the ambient sounds at three locations in the wilderness of Aialik Bay in Kenai Fjords National Park, Alaska between 25 June and 21 September 2019. My aim was to capture an ecoacoustic snapshot of the coastal soundscape to provide a comparable baseline for evaluating wilderness characteristics defined by the Wilderness Act of 1964. I visually and empirically characterized the Aialik Bay wilderness soundscape using the acoustic metrics of soundscape power (normalized watts/kHz) and Normalized Difference Soundscape Index (NDSI) from 5373 five-minute recordings, combined with visual and aural spectral examination of 4386 recordings. Soundscape power exhibited similar patterns across frequency intervals with sound sources primarily occurring in the low-frequency (1–2 kHz) and mid-frequency (2–5 kHz) intervals. Significant differences within frequency intervals between sites suggested the presence of distinct sonotopes. Low-frequency sounds were dominant across all three sites with peak soundscape power values across study days and 24 h timeframes attributed to wind and occasional periods of technophony emitted from commercial tour boats and private boating activities. Low-frequency geophony from wave action was ever present. Technophony exhibited some predictable patterns consistent with the timing of sightseeing boat tours. Peak values of soundscape power at mid-frequencies were attributed to the geophony of rain. Although biophonies were less common than geophonies, the choruses of songbirds were prevalent in July and promptly occurred daily between 0300 and 0600. Biophonies generally declined over the course of the day. All sites displayed negative NDSI values over most study days and consistently negative values over 24 h time frames, indicating a soundscape primarily influenced by low-frequency geophony and periods of technophony. However, NDSI values showed patterns and peaks similar to biophonies at mid-frequency intervals indicating biophony was still a notable contribution to this geophony-dominant soundscape. Despite the acoustic footprint of motorboat noise detected at all sample sites, the soundscape of the Aialik Bay wilderness was dominated by the natural sounds of geophony, biophony, and occasional periods of natural quiet indicative of a wilderness only partially impacted by technophony.

Long-term deep learning-facilitated environmental acoustic monitoring in the Capital Region of New York State

Article

Feb 2021
ECOL INFORM

The effect of anthropogenic activity on animal communication is of increasing ecological concern. Passive acoustic recording offers a robust, minimally disruptive, long-term approach to monitoring species interactions, particularly because many indicator species of environmental health factors such as biodiversity, habitat quality, and pollution produce distinct vocalizations. Machine learning algorithms have been used in recent decades to automatically analyze the large quantities of audio data that result. In this study, a microphone array was used to collect continuous audio data at a site in the Capital Region of New York State for twelve months, resulting in over 8000 h of recordings. A 19-class database containing a variety of bio- and anthrophony was used to train a convolutional neural network in order to generate a reliable record of species-specific calling activity for the entire study period. These results were used to calculate an acoustics-based pseudo-species richness and abundance distribution. Additionally, heatmap plots were used to visualize (i) the time of day (x), sound category (y), and predicted number of sonic events for an average 30-day period and (ii) the day of the year (x), time of day (y), and predicted number of sonic events for each sound category. The correlations between these sonic events and various abiotic factors such as number of daylight hours, temperature, and weather activity were also examined.

The quantitative relation between ambient soundscapes and landscape development intensity in North Central Florida

Article

Full-text available

Jan 2020
LANDSCAPE ECOL

Context It is widely accepted that wildlife is subjected to detrimental human noise within urban landscapes but little is known about how the intensity of land use changes soundscapes. Objectives The objective of this research was to produce quantitative associations between characteristics of ambient soundscapes and land use intensity. These relations were used to examine the 2 kHz demarcation between anthrophony and biophony and compare the impact of different sized contributing areas on ambient soundscape characteristics. Methods This study related the surrounding land use intensity of 67 sites in north central Florida (USA) to several metrics describing their recorded soundscapes. Land use intensity was measured remotely at three scales using the landscape development intensity index (LDI). Results The analysis revealed that the LDI index had a statistically significant effect on soundscape characteristics after controlling for important factors such as climate, season, and attenuation due to hard ground. The trends between LDI and soundscape confirmed that human generated sounds are loud, continuous, and occupy low frequencies. The evenness of the sound distribution decreased with landscape intensity and LDI correlated significantly with sound below 3 kHz. Land use intensity within a 100 and 500-m radius contributing area were most closely related to soundscape metrics. Conclusions LDI is a tool with the potential to predict the extent and intensity of anthropogenic noise disturbance on wildlife from remote sensing data. The utility of this tool allows for widespread application to identify and mitigate conflicts in the acoustic realm between human noise and wildlife.

Paisagem sonora da trilha do Capão do Tigre - UFPR, Curitiba, Paraná

Conference Paper

Full-text available

Jul 2018

Resumo A paisagem sonora é composta pelo total de sons presentes em um ambiente, podendo ser naturais ou artificiais, incluindo-se a capacidade física dos componentes presentes em transmiti-la. Este trabalho teve como objetivo caracterizar a paisagem sonora de uma trilha situada em um fragmento florestal urbano (Capão do Tigre) de Curitiba, Paraná. A coleta dos dados foi realizada durante o outono/2018, em 14 pontos diferentes na floresta, na parte interna e externa. Foi utilizado um decibelímetro modelo DEC-470 para a avaliação da pressão sonora. Foram coletados os níveis do som ambiente com compensação em A (simulando a recepção humana) (dB (A)) e equivalente (dBeq) e realizada a classificação do som em cada ponto de coleta. Foi observada diferença significativa das condições do som, sendo os maiores níveis de pressão sonora observados nos pontos P1 e P11 com 75,5 e 76,5 dB (A), respectivamente. Nesses pontos também foram encontrados os maiores valores de dBeq (56,2 e 56,1 dBeq), os quais encontram-se acusticamente poluídos. Os valores mínimos registrados foram nos pontos P4 (36,2 dB (A)) e P10 (36,7 dB (A)). Os menores valores de dBeq foram registrados nos pontos P3, P4, P7 e P8 com 46,4, 46,9, 47,1 e 47,6 dBeq. Também foi observada diferença entre os valores medidos externa e internamente, com valor médio de 5,9 dBeq. O ambiente sonoro da trilha apresenta diferentes tipos de sons em sua composição, com predominância de sons artificiais provenientes de tráfego (uma rodovia próxima a floresta) e sons bióticos de animais, na sua maioria pássaros. Palavras-chave: Fragmento florestal urbano; Ruído sonoro; Vegetação. 1. Introdução A paisagem sonora é composta pelo total de sons presentes em um ambiente, podendo ser naturais ou artificiais, incluindo-se a capacidade física dos componentes presentes em transmiti-los (GOSWAMI, 2011; FARINA; PIERETTI, 2012; MOLINA et al., 2013). Nos ambientes naturais, a paisagem sonora pode ser constituída unicamente por sons naturais ou pela sobreposição desses com os de atividades humanas (MOLINA et al., 2013), compostos principalmente por sons desagradáveis, os quais constituem os ruídos sonoros. Os elementos que compõe uma paisagem sonora são estritamente conectados, uma vez que os padrões de vegetação, as infraestruturas e a distribuição de animais influenciam na produção e propagação dos sons (FARINA; PIERETTI, 2012). A vegetação é o elemento mais eficiente na atenuação do ruído nas áreas urbanas, devido a capacidade que as folhas das plantas possuem de absorver o ruído e de transmitir o som para outras superfícies, alterando a sua direção e misturando sons indesejados com outros mais agradáveis (YANG et al., 2011; CHOUDHURY, 2013). A paisagem sonora das cidades é um indicativo da qualidade de vida nesses ambientes (GOSWAMI, 2011). Brambilla et al. (2013) acrescentam que os benefícios à saúde devem ser preservados e melhorados, especialmente nas áreas verdes urbanas, pois constituem ilhas de atenuação de ruído sonoro cercadas por áreas poluídas sonoramente. Além disso, as áreas verdes podem fornecer conforto sonoro, ao promover sensação de relaxamento e bem-estar à população (YANG et al., 2011). Segundo Curitiba (2002), o som é a vibração acústica capaz de provocar sensações auditivas, enquanto que o ruído é o som que pode causar perturbação ao sossego público ou efeitos psicológicos e fisiológicos negativos em seres humanos e animais. Curitiba (2002) ainda define a poluição sonora

Gaps in terrestrial soundscape research: It´s time to focus on tropical wildlife.

Article

Full-text available

Oct 2020

Data selection in frog chorusing recognition with acoustic indices

Article

Sep 2020
ECOL INFORM

This research explores the data selection problem in acoustic recognition of two co-existing sibling frog species from long-duration field recordings. This study explores the data selection problem in species recognition with machine learning, including instance selection and acoustic index feature selection. Our target species are two co-existing frog species. The Wallum Sedgefrog (Litoria olongburensis) is the most threatened acid frog species, facing habitat loss and degradation across much of their distribution, in addition to further pressures associated with anecdotally-recognised competition from it's sibling species, the Eastern Sedgefrog (Litoria fallax). Monitoring the calling behaviours of these two species is essential for informing L. olongburensis management and protection, and for obtaining ecological information about the process and implications of their competition. In order to recognise them from recordings, automated recognisers, instead of manual surveys, are required due to the overwhelmingly large volume of acoustic data. However, it costs much time and effort to annotate acoustic data, which results in a lack of labelled data for training recognisers. In addition, the composition of field audio recordings is complex and varies according to weather conditions, seasonal changes and animal activities. In this case, the chorusing behaviours of these two frog species can be greatly affected by weather conditions, for example, rains. Since we can only select limited amount of data from a very diverse data pool to annotate, it is important to explore how the selection of instances and features affects the performance of recognisers. In this paper, we selected two 24-h audio datasets from different weather conditions as our dataset. We first give a detailed visual comparison of them with false-colour spectrograms. Then we use datasets from individual days, their combination and a synthetic set constructed from them to evaluate the impact of different training instances on the recognition performance. We also analyses the effectiveness of acoustic index features. The experimental results show that models trained on data of a vocalisation-intense day or a normal day do not work well on each other. However, extra data from a normal-day dataset does help the recognition on a vocalisation-intense day, especially when the composition of the training set is consistent with the real-life weather condition ratio. Generally, including more data in training set is helpful, but limiting vocalisation-intense data as their ratio in real life help optimise the performance of recognisers. As for the selection of acoustic index features, a good recognition performance on different chorusing behaviours requires different sets of features.

Acoustic complexity indices reveal the acoustic communities of the old- growth Mediterranean forest of Sasso Fratino Integral Natural Reserve (Central Italy)

Article

Full-text available

Sep 2020

The Sasso Fratino Integral Natural Reserve (Central Italy), a rare example of climax Mediterranean forest, provides an extraordinary opportunity to create an important soundscape reference of old-growth forest. In this study, we describe the soundscape of three localities (Lama, Sasso 950, Sasso 1400) representative of a gradient of variety and complexity of habitats, recorded during the period 10 May to 9 June 2017. Our results reveal temporal partitioning into acoustically homogeneous periods across 24 h suggesting that soniferous species (mainly birds) adopt ecological routines in which their acoustic activity is organized according to specific transient physiological needs. We processed multi-temporal aggregates of 1, 5, 10, and 15 s recordings and calculated the Acoustic Signature (AS) with four new indices: Ecoacoustic Events (EE), Acoustic Signature Dissimilarity (ASD), and their fractal dimensions (D EE and D ASD), derived from the Acoustic Complexity Index (ACI). The use of the EE and ASD greatly improved the AS interpretation, adding further details such as the emergence of a clear sequence of patterns consistent with the daily evolution of the overall soundscape. D EE and D ASD confirm the patterns observed using the AS, but provide more clarity and detail about the great acoustic complexity that exists across temporal scales in this old-growth forest. The temporal turnover of different acoustic communities occurs as a result of a gradual shift of different homogenous acoustic properties. We conclude that soniferous species use distinct, species-specific temporal resolutions according to their physiological and ecological needs and that the fractal approach used here provides a novel tool to overcome the difficulties associated with describing multi-temporal acoustic patterns.

A new soundscape analysis tool: Soundscape Analysis and Mapping System (SAMS)

Article

Dec 2020
APPL ACOUST

Biogeographical and analytical implications of temporal variability in geographically diverse soundscapes

Article

May 2020
ECOL INDIC

Unprecedented rates of biodiversity loss and intensifying human attempts to rectify the biodiversity crisis have heightened the need for standardized, large-scale, long-duration biodiversity monitoring at fine temporal resolution. While some innovative technologies such as passive acoustic monitoring are well suited for such monitoring challenges, many questions remain as to how they should be scaled out and optimally implemented across ecosystems. Our research questions center on temporal sampling regimes—how frequently and how long one should collect data to represent biodiversity conditions over a given timeframe. Addressing this concern in the context of passive acoustic monitoring, we investigated whether temporal soundscape variability—the characteristic short-term acoustic change in an environment—is consistent across ecosystems and times of day, and we considered how various temporal subsampling schemes affect the representativeness of resultant acoustic index values, relative to continuous sampling. We quantified soundscape variability at eight sites across four continents based on temporal autocorrelation ranges and standard deviations of acoustic index values, and we created a heuristic model to classify types of soundscape variability based on those two variables. Drawing on values derived from three distinct acoustic indices, we found that the characteristic temporal variability of soundscapes varied between sites and times of day (dawn, daytime, dusk, and nighttime). Some sites exhibited little difference in variability between times of day whereas other sites exhibited greater within-site differences between times of day than many inter-site differences. Daytime soundscapes generally tended to exhibit more temporal variability than nighttime soundscapes. We also compared potential subsampling schemes that could be advantageous in terms of power, data storage, and data analysis costs by modeling subsample error as a function of total analysis time and number of subsamples within a larger block of time. Greater numbers of evenly distributed subdivisions drastically increased the representativeness of a sampling scheme, while increases in subsample duration yielded fairly minimal gains in representativeness between 33 and 67% of the full time one wishes to represent. Generally, our results show that for a long-term, fine temporal resolution monitoring program, one should record in evenly distributed durations at least as short as 1 min while only recording up to a third of the time one wishes to represent. While more continuous monitoring can be advantageous and necessary in many cases, current economic and logistical limitations in power, data storage, and analysis capabilities will often warrant optimized subsampling designs.

A soundscape assessment of the Sasso Fratino Integral Nature Reserve in the Central Apennines, Italy

Article

Dec 2019

Ecoacoustics investigates natural and anthropogenic sounds and their relationship with the environment. It is a powerful tool for biodiversity monitoring, management and conservation and also with regards to the global climate change issue. This study, based on data collected in 2017, describes for the first time the soundscape of the Sasso Fratino Integral Nature Reserve (INR) in Italy, an area characterised by the almost absence of anthropogenic noise, where we selected three recording sites within and adjacent the reserve. We adopted a double approach: one qualitative, based on visual screening of compact daily spectrograms; the other quantitative, by generating acoustic indices. In general, all sites are characterised by quiet nights and very acoustically dense daylight hours, with a composite biophony occupying the range 1500–9000 Hz. Moreover, the principal component analysis shows that the sites inside and outside the reserve are well differentiated and distinctly clustered, which could be due to their spatial heterogeneity and to the biophony’s different contributions. In this case, our results agree with the recognition of sonic patterns, or sonotopes, related to the different overlapping of biotic and abiotic sonic agents. The long-term acoustic data collection allows a reference repository to be built for monitoring the INR’s biophony status and evolution: as any human presence or intervention is currently prohibited, only external global changes could be considered as possible factors influencing any shift in the species’ presence and distribution inside the reserve.

Recognition of Frog Chorusing with Acoustic Indices and Machine Learning

Conference Paper

Full-text available

Feb 2020

This research explores the recognition of choruses of two co-existing sibling frog species in long-duration field recordings using false-colour spectrograms and acoustic indices. Acid frogs are a group of endemic frogs that are particularly sensitive to habitat change and competition from other species. The Wallum Sedgefrog (Litoria olongburensis) is the most threatened acid frog species facing habitat loss and degradation across much of their distribution, in addition to further pressures associated with anecdotally-recognised competition from their sibling species, the Eastern Sedgefrogs (Litoria fallax). Monitoring the calling behaviours of these two species is essential for informing L. olongburensis management and protection, and for obtaining ecological information about the process and implications of their competition. Considering the cryptic nature of L. olongburensis and the sensitivity of their habitat to human disturbance, passive acoustic monitoring is a suitable method for monitoring this species. However, manually processing the large quantities of acoustic data collected using these methods is time-consuming and not feasible in the long-term. Therefore, there is a high demand for automated acoustic recognition tools to efficiently search months of recordings and identify target species. Our research provides more insight on how to choose acoustic features that efficiently recognise species from large-scale field-collected recordings at a larger scale. The experimental results show that these techniques are useful in identifying choruses of the two competitive frog species with an accuracy of 76.7% on identifying four acoustic patterns (whether the two species occurred).

Acoustic Complexity Index to assess Benthic Biodiversity of a Partially Protected Area in the Southwest of the UK

Article

Dec 2019
ECOL INDIC

Practical Issues in Studying Natural Vibroscape and Biotic Noise

Chapter

Nov 2019

In nature, vibrational communication takes place in an ecological context and in a complex vibrational environment that can be a major driver of evolution. Vibroscape is a collection of biological, geophysical and anthropogenic vibrations emanating from a given landscape to create unique vibrational patterns across a variety of spatial and temporal scales. Here, we discuss basic concepts and propose some basic terminology in this field of research. Vibroscape is virtually unexplored so far and we also provide some guidelines on how to approach fieldwork associated with vibroscape studies, as well as analyses of recordings obtained in the field. Vibroscape research is still facing technical challenges; however, we urge further studies in this area in order to provide much needed information on natural vibrational communities and sources of biotic, as well as anthropogenic vibratory noise.

Gaps in terrestrial soundscape research: It's time to focus on tropical wildlife

Article

Nov 2019

There has been a body of research examining the sounds produced in landscapes. These sounds are commonly defined as soundscapes, however, the term is often used in different contexts. To understand how the various meanings attributed to soundscapes, we identified how soundscapes are represented in the scientific literature and identified current knowledge gaps in soundscape research focusing on terrestrial environments. We conducted a quantitative review of published papers with the keyword soundscape available at Web of Science and Scopus databases. A total of 1,309 abstracts and a subset of about 5% (N=68) complete papers and reviews published from 1985 to 2017 were read and analysed, identifying types of sound, types of environment and focal species studied, as well as study regions and climates. By identifying the current focus of research, we also identified gaps and research opportunities. Research was biased towards temperate regions, terrestrial environments, and the impacts on humans in urban areas. Although most of the world’s biodiversity is concentrated in tropical wilderness areas, these regions had fewer studies attributed to them. Given the importance of tropical landscapes for biodiversity conservation, we strongly suggest that more research should be undertaken in the tropics, with a particular focus on wildlife in these regions. Furthermore, soundscape research (methods and tools) should increasingly target the anthropogenic impacts on wildlife, including behavioural and physiological changes, alongside the current focus on human-sound interactions and the approach used by bioacoustics methods.

How well do acoustic indices measure biodiversity? Computational experiments to determine effect of sound unit shape, vocalization intensity, and frequency of vocalization occurrence on performance of acoustic indices

Article

Nov 2019
ECOL INDIC

Passive acoustic monitoring of biotic sounds is increasingly popular in conservation biology. Among vocalizing animals, birds are most frequently studied and multiple acoustic indices have been proposed for rapid acoustic assessment of avian diversity. Preliminary results suggest that several indices can be used as proxies for bird species richness, however it is still unclear to what extent different conditions of bird vocalizations affect the relationship between indices and bird species richness-should it matter if the bird vocalizations contain different sound unit shapes, or if the frequency of vocalization occurrence differs, or if the vocalizations are made with various intensities? In this work, seven commonly used acoustic indices were tested using three controlled computational experiments with real-world recordings to provide an objective measure of each index's performance for answering the aforementioned questions. In the experiments, different options of sound unit shape and frequency of vo-calization occurrence were precisely controlled and intensity variations were expressed as different signal-to-noise ratios (SNR) of the vocalizations. The first experiment showed that three indices (the acoustic entropy index (H), acoustic diversity index (ADI), and acoustic evenness index (AEI)) performed better than the other four, showing moderate correlations with avian species richness. The second experiment revealed that ADI for each sound unit shape tended towards a constant value with increasing frequency of vocalization occurrence while the influence from frequency of vocalization occurrence on H and AEI varied with different sound unit shape options. Our third experiment showed that the vocalization intensity affected the values of these three indices while the performance disparity among different sound unit shapes for only ADI explicitly appeared a decreasing tendency with increasing vo-calization intensities. We conclude that ADI, among the tested indices, is relatively more robust with regard to bird species richness surveys when sound unit shape, frequency of vocalization occurrence, and vocalization intensity are considered. Meanwhile, since multiple indices are usually applied together to provide a comprehensive observation, the above acoustic dimensions should be taken into account especially in comparative research of different bird communities.

Anthropogenic noise does not surpass land cover in explaining habitat selection of Greater Prairie-Chicken (Tympanuchus cupido)

Article

Full-text available

Oct 2019
CONDOR

Over the last century, increasing human populations and conversion of grassland to agriculture have had severe consequences for numbers of Greater Prairie-Chicken (Tympanuchus cupido). Understanding Greater Prairie-Chicken response to human disturbance, including the effects of anthropogenic noise and landscape modification, is vital for conserving remaining populations because these disturbances are becoming more common in grassland systems. Here, we evaluate the effect of low-frequency noise emitted from a wind energy facility on habitat selection. We used the Normalized Difference Soundscape Index, a ratio of human-generated and biological acoustic components, to determine the impact of the dominant acoustic characteristics of habitat relative to physical landscape features known to influence within–home range habitat selection. Female Greater Prairie-Chickens avoided wooded areas and row crops but showed no selection or avoidance of wind turbines based on the availability of these features across their home range. Although the acoustic environment near the wind energy facility was dominated by anthropogenic noise, our results show that acoustic habitat selection is not evident for this species. In contrast, our work highlights the need to reduce the presence of trees, which have been historically absent from the region, as well as decrease the conversion of grassland to row-crop agriculture. Our findings suggest physical landscape changes surpass altered acoustic environments in mediating Greater Prairie-Chicken habitat selection.

The Call of the Wild: investigating the potential for ecoacoustic methods in mapping wilderness areas

Article

Aug 2019
SCI TOTAL ENVIRON

The critical importance of wilderness areas (WAs) for biodiversity conservation and human well-being is well established yet mapping criteria on which WA management policies are based take neither into account. Current WA mapping methods are framed in terms of absence of anthropogenic influence, and created using visual satellite data, obviating consideration of the ecological or anthropogenic value of WAs. In this paper we suggest that taking the acoustic environment into account could address this lacuna. We report the first investigation into the potential for ecoacoustic methods to complement existing geophysical approaches. Participatory walks, including in situ questionnaires and ecoacoustic surveys were carried out at points along transects traversing urban-wilderness gradients at four study sites in the Scottish Highlands and French Pyrenees. The relationships between a suite of six acoustic indices (AIs), wilderness classifications and human subjective ratings were examined. We observed significant differences between five out of six AIs tested across wilderness classes, demonstrating significant differences in the soundscape across urban-wild gradients. Strong, significant correlations between AIs, wilderness classes and human perceptions of wildness were observed, although magnitude and direction of correlations varied across sites. Finally, a compound acoustic index is shown to strongly predict mapped wildness classes (up to 95% variance explained MSE 0.22); perceived wilderness and biodiversity are even more strongly predicted. Together these results demonstrate that the acoustic environment varies significantly along urban-wild gradients; AIs reveal details of environmental variation excluded under current methods, and capture key facets of the human experience of wildness. An important next step is to ascertain the ecological and anthropogenic relevance of these differences, and develop new automated acoustic analysis methods suited to mapping the environmental characteristics of WAs. Taken together, our results suggest that future management of WAs could benefit from ecoacoustic methods to take the biosphere and anthroposphere into account.

Biogeographical and analytical implications of temporal variability in geographically diverse soundscapes

Article

Sep 2020
ECOL INDIC

Extreme environmental conditions lead to a collapsed avian soundscapes; an agent- based model

Preprint

Full-text available

Apr 2022

Climate change is increasing aridity in grassland and desert habitats across the southwestern United States, reducing available resources and drastically changing the breeding habitat of many bird species. Increases in aridity reduce sound propagation distances, potentially impacting habitat soundscapes, and could lead to a breakdown of the avian soundscapes in the form of loss of vocal culture, reduced mating opportunities, and local population extinctions. We developed an agent-based model to examine how changes in aridity will affect both sound propagation and the ability of territorial birds to audibly contact their neighbors. We simulated vocal signal attenuation under a variety of environmental scenarios for the south central semi-arid prairies of the United States, ranging from contemporary weather conditions to predicted droughts under climate change. We also simulated how changes in physiological conditions, mainly evaporative water loss (EWL), would affect singing behavior. Under contemporary and climate change induced drought conditions, we found significantly fewer individuals successfully contacted all adjacent neighbors than did individuals in either the contemporary or predicted climate change conditions. We also found that at higher sound frequencies and higher EWL, fewer individuals were able to successfully contact all their neighbors, particularly in the drought and climate change drought conditions. These results indicate that climate change-mediated aridification may disrupt the avian soundscape, such that vocal communication no longer effectively functions for mate attraction or territorial defense. As climate change progresses increased aridity in current grasslands may favor shifts toward low frequency songs, colonial resource use, and altered songbird community compositions.

How are nature-based solutions contributing to priority societal challenges surrounding human well-being in the United Kingdom: a systematic map

Article

Full-text available

Dec 2020

Background The concept of nature-based solutions (NBS) has evolved as an umbrella concept to describe approaches to learning from and using nature to create sustainable socio-ecological systems. Furthermore, NBS often address multiple societal challenges that humans are facing in the medium to long-term and as such can enhance human well-being (HWB). This study was commissioned to fulfil the need for a targeted systematic evidence map on the linkage between NBS and HWB to support focused research going forward that addresses the key knowledge needs of policy makers in the UK and beyond. Methods A consultation with policy makers and government agency staff (n = 46), in the four component parts of the UK (England, Wales, Scotland, Northern Ireland) was conducted in spring 2019. This identified four key societal challenges of operational experience lacking a scientific evidence base. Three of these challenges related to management issues: NBS cost-efficacy, governance in planning, environmental justice. The fourth challenge related to the acoustic environment (soundscape). Using systematic methods, this study searched for and identified studies that assessed NBS on HWB with regard to these four selected societal challenges. Review findings A total of 7287 articles were returned from the systematic search and screened for suitability at the level of title and abstract. A total of 610 articles passed screening criteria to warrant full text screening. Of these, 115 studies met the full text criteria for eligibility in the final systematic map database. Included studies were coded for twelve NBS interventions and ten HWB related outcome categories. Most of the evidence reviewed referred to natural, blue or green infrastructure in the urban environment and focused on economic, material and health aspects of HWB. Less than 2% of studies identified in the searches robustly reported the role of NBS actions or interventions on HWB compared with non-NBS actions or interventions Conclusion This systematic map found the evidence base is growing on NBS-HWB linkages, but significant biases persist in the existing literature. There was a bias in favour of the urban environment and restoration studies focused on conservation aspects, with only a few studies investigating the full suite of advantages to HWB that can be delivered from NBS actions and interventions. The soundscape was the least studied of the societal challenges identified as being of key importance by policy makers, with cost-efficiency the most reported. There was a lack of robust long-term studies to clearly test the potential of NBS regarding the HWB outcomes compared with non-NBS alternatives. This lack of robust primary knowledge, covering all four key societal challenges identified, confirms that the knowledge gaps identified by the policy makers persist, and highlights a clear research need for long-term, transdisciplinary studies that focus on comparisons between NBS and non-NBS alternatives

Intersections of Soundscapes and Conservation: Ecologies of Sound in Naturecultures

Article

Mar 2019

Temporal Soundscape Patterns in a Panamanian Tree Diversity Experiment: Polycultures Show an Increase in High Frequency Cover

Article

Full-text available

Feb 2022

In this ecoacoustic study we used the setting of a tropical tree diversity planted forest to analyze temporal patterns in the composition of soundscapes and to test the effects of tree species richness on associated biodiversity measured as acoustic diversity. The analysis of soundscapes offers easy, rapid and sustainable methods when assessing biodiversity. During the last years the quantification of regional or global acoustic variability in sounds and the analysis of different soundscapes has been evolving into an important tool for biodiversity conservation, especially since case studies confirmed a relationship between land-use management, forest structure and acoustic diversity. Here we analyzed soundscapes from two seasons (dry and rainy season) and aurally inspected a subset of audio recordings to describe temporal patterns in soundscape composition. Several acoustic indices were calculated and we performed a correlation analysis and a non-metric multidimensional scaling analysis to identify acoustic indices that: (i) were complementary to each other and such represented different aspects of the local soundscapes and (ii) related most strongly to differences in acoustic composition among tree species richness, season and day phase. Thus, we chose “High Frequency Cover,” “Bioacoustic Index,” and “Events Per Second” to test the hypothesis that acoustic diversity increases with increasing tree species richness. Monocultures differed significantly from polycultures during night recordings, with respect to High Frequency Cover. This index covers sounds above 8 kHz and thus represents part of the orthopteran community. We conclude that increasing tree species richness in a young tropical forest plantation had positive effects on the vocalizing communities. The strongest effects were found for acoustic activity of the orthopteran community. In contrast to birds, orthopterans have smaller home ranges, and are therefore important indicator species for small scale environmental conditions.

Towards a multisensor station for automated biodiversity monitoring

Article

Full-text available

Jan 2022
BASIC APPL ECOL

Rapid changes of the biosphere observed in recent years are caused by both small and large scale drivers, like shifts in temperature, transformations in land-use, or changes in the energy budget of systems. While the latter processes are easily quantifiable, documentation of the loss of biodiversity and community structure is more difficult. Changes in organismal abundance and diversity are barely documented. Censuses of species are usually fragmentary and inferred by often spatially, temporally and ecologically unsatisfactory simple species lists for individual study sites. Thus, detrimental global processes and their drivers often remain unrevealed. A major impediment to monitoring species diversity is the lack of human taxonomic expertise that is implicitly required for large-scale and fine-grained assessments. Another is the large amount of personnel and associated costs needed to cover large scales, or the inaccessibility of remote but nonetheless affected areas. To overcome these limitations we propose a network of Automated Multisensor stations for Monitoring of species Diversity (AMMODs) to pave the way for a new generation of biodiversity assessment centers. This network combines cutting-edge technologies with biodiversity informatics and expert systems that conserve expert knowledge. Each AMMOD station combines autonomous samplers for insects, pollen and spores, audio recorders for vocalizing animals, sensors for volatile organic compounds emitted by plants (pVOCs) and camera traps for mammals and small invertebrates. AMMODs are largely self-containing and have the ability to pre-process data (e.g. for noise filtering) prior to transmission to receiver stations for storage, integration and analyses. Installation on sites that are difficult to access require a sophisticated and challenging system design with optimum balance between power requirements, bandwidth for data transmission, required service, and operation under all environmental conditions for years. An important prerequisite for automated species identification are databases of DNA barcodes, animal sounds, for pVOCs, and images used as training data for automated species identification. AMMOD stations thus become a key component to advance the field of biodiversity monitoring for research and policy by delivering biodiversity data at an unprecedented spatial and temporal resolution.

The stability of ecosystems under global environmental change

Thesis

Full-text available

Jan 2022

Samuel RP-J Ross

Through global environmental change, humans are modifying the planet at an unprecedented rate and scale, triggering the ongoing biodiversity and climate crises. Ecological stability and the consistency of nature’s contributions to people are fundamental to the continued sustainability of human societies. Stability is a complex and multidimensional concept including components such as variability in time and space and the resistance to and recovery from disturbances. Global change has the potential to destabilise ecosystems, but the form and strength of the relationship between different global change drivers and dimensions of stability remains understudied, precluding general or mechanistic understanding. Here, I combine theory, a field experiment, and observational data from a high-resolution acoustic monitoring network to reveal the potential for multiple global change drivers to erode multidimensional ecological stability. Critically, I also show how biodiversity and natural habitats can buffer the destabilising effects of global environmental change on ecosystems and soundscapes, providing vital insurance against disturbance. In an era characterised by unrelenting global change and intensifying disturbance regimes, my results provide a key step towards a generalisable understanding—and ultimately management—of the stability of ecosystems and their contributions to human wellbeing.

Multi-Index Ecoacoustics Analysis for Terrestrial Soundscapes: A New Semi-Automated Approach Using Time-Series Motif Discovery and Random Forest Classification

Article

Full-text available

Dec 2021

High rates of biodiversity loss caused by human-induced changes in the environment require new methods for large scale fauna monitoring and data analysis. While ecoacoustic monitoring is increasingly being used and shows promise, analysis and interpretation of the big data produced remains a challenge. Computer-generated acoustic indices potentially provide a biologically meaningful summary of sound, however, temporal autocorrelation, difficulties in statistical analysis of multi-index data and lack of consistency or transferability in different terrestrial environments have hindered the application of those indices in different contexts. To address these issues we investigate the use of time-series motif discovery and random forest classification of multi-indices through two case studies. We use a semi-automated workflow combining time-series motif discovery and random forest classification of multi-index (acoustic complexity, temporal entropy, and events per second) data to categorize sounds in unfiltered recordings according to the main source of sound present (birds, insects, geophony). Our approach showed more than 70% accuracy in label assignment in both datasets. The categories assigned were broad, but we believe this is a great improvement on traditional single index analysis of environmental recordings as we can now give ecological meaning to recordings in a semi-automated way that does not require expert knowledge and manual validation is only necessary for a small subset of the data. Furthermore, temporal autocorrelation, which is largely ignored by researchers, has been effectively eliminated through the time-series motif discovery technique applied here for the first time to ecoacoustic data. We expect that our approach will greatly assist researchers in the future as it will allow large datasets to be rapidly processed and labeled, enabling the screening of recordings for undesired sounds, such as wind, or target biophony (insects and birds) for biodiversity monitoring or bioacoustics research.

Expanding NEON biodiversity surveys with new instrumentation and machine learning approaches

Article

Full-text available

Nov 2021

A core goal of the National Ecological Observatory Network (NEON) is to measure changes in biodiversity across the 30‐yr horizon of the network. In contrast to NEON’s extensive use of automated instruments to collect environmental data, NEON’s biodiversity surveys are almost entirely conducted using traditional human‐centric field methods. We believe that the combination of instrumentation for remote data collection and machine learning models to process such data represents an important opportunity for NEON to expand the scope, scale, and usability of its biodiversity data collection while potentially reducing long‐term costs. In this manuscript, we first review the current status of instrument‐based biodiversity surveys within the NEON project and previous research at the intersection of biodiversity, instrumentation, and machine learning at NEON sites. We then survey methods that have been developed at other locations but could potentially be employed at NEON sites in future. Finally, we expand on these ideas in five case studies that we believe suggest particularly fruitful future paths for automated biodiversity measurement at NEON sites: acoustic recorders for sound‐producing taxa, camera traps for medium and large mammals, hydroacoustic and remote imagery for aquatic diversity, expanded remote and ground‐based measurements for plant biodiversity, and laboratory‐based imaging for physical specimens and samples in the NEON biorepository. Through its data science‐literate staff and user community, NEON has a unique role to play in supporting the growth of such automated biodiversity survey methods, as well as demonstrating their ability to help answer key ecological questions that cannot be answered at the more limited spatiotemporal scales of human‐driven surveys.

A Terminology Standard for Underwater Acoustics and the Benefits of International Standardization

Article

Full-text available

Nov 2021
IEEE J OCEANIC ENG

Applications of underwater acoustics include sonar, communication, geophysical imaging, acoustical oceanography, and bioacoustics. Specialists typically work with little interdisciplinary interaction, and the terminology they employ has evolved separately in each discipline, to the point that transdisciplinary misunderstandings are common. Furthermore, increasing societal concern about possible detrimental effects of underwater noise on aquatic animals has led national and international regulators to require monitoring of underwater noise, with a consequent need for interdisciplinary harmonization of terminology. By adopting a common language, we facilitate the effective communication of concepts and information in underwater acoustics, whether for research, technology, or regulation. In the words of William H. Taft, “Don't write so that you can be understood, write so that you can't be misunderstood.” Clear definitions of widely used terms are needed, such as those used for the characterization of sound fields (e.g., “soundscape” and “ambient noise”), sound sources (“source level” and “source waveform”), sound propagation (“transmission loss” and “propagation loss”), and sound reception (“hearing threshold” and “frequency weighting function”). Terms that are used synonymously in one application have different meanings in another (examples include “hearing threshold” versus “detection threshold” and “transmission loss” versus “propagation loss”). Distinct definitions for these and many other acoustic terms are provided in a standard published in April 2017 by the International Organization for Standardization, ISO 18405. This article summarizes ISO 18405 and the process that led to the published definitions, including the reasons for omitting some terms.

Loss of winter wonderland: proximity to different road types has variable effects on winter soundscapes

Article

Full-text available

Oct 2021

ContextMost data collection and analyses in soundscape ecology have focused on summer or breeding seasons in urban or protected landscapes, missing important acoustic dynamics in winter, non-breeding periods and in agricultural landscapes, a land-use that constitutes 39% of ice-free surface globally.Objectives To address these gaps, we examined the variation of winter soundscapes across a rural agricultural landscape of Nebraska, USA. We compared high and low traffic sites, testing if traffic levels affected soundscape structure.Methods We recorded sound over two winters at 19 sites located adjacent to major and minor roadways. We calculated eight unique soundscape indexes to quantify the soundscape over time as a function of traffic and land cover. We applied filters at 80, 1000, and 2000 Hz.ResultsWe found clear statistical differences between high and low traffic sites in 7 of 8 soundscape indexes. Soundscape varied throughout the day, but not throughout the season. There was a clear negative correlation between technophony (human-derived sounds) and biophony (ecologically derived sounds) across sites. We found that not all indices may be suitable for all ecosystems.Conclusions We quantified the effects of noise pollution on the soundscape of understudied habitats during winter months. By using soundscape indexes as surrogates for biodiversity, acoustic sampling could be an effective method for monitoring biodiversity when traditional methods may be ineffective or too costly. However, caution needs to be taken when choosing indices.

Environmental sound as a mirror of landscape ecological integrity in monitoring programs

Article

Full-text available

Jun 2021

tSoundscape research has acquired a paramount role in biodiversity conservation as it may provide timelyand reliable information about the ecological integrity. The relationship between soundscape complexityand ecological integrity in highly biodiverse environments, as well as the factors affecting this relation-ship require a thorough understanding. We determined how the soundscape relates to the landscapeecological integrity at different spatial and temporal scales in a montane forest in the northern Andes ofColombia. Between May–July 2018 we obtained acoustic recordings from 31 sampling sites in the pro-tected area of a hydropower plant, and estimated nine acoustic indices and an ecological integrity index(EII) derived from fragmentation, connectivity, and habitat quality. Five of the acoustic indices, linked tothe evenness of the acoustic signals and levels of the biophonic signals, were associated with changesin the EII and indicated the presence of more even, saturated, and acoustically rich soundscapes in siteswith higher integrity. Relationships between acoustic indices and the EII were stronger at a smaller spa-tial scale (100 m) and responded to daily variation of the soundscape, with the strongest associationsoccurring mainly from sunrise to noon. We show that acoustic indices measuring the evenness of theacoustic activity distribution and the number of frequency peaks reliably reflect the changes in the eco-logical integrity, and can be integrated with remote sensing as a tool for landscape management. Ourresults highlight the soundscape analysis as a feasible approach for the monitoring and conservationplanning of acoustically unknown and threatened Andean landscapes.

Looking for the -scape in the sound: Discriminating soundscapes categories in the Sonoran Desert using indices and clustering

Article

Full-text available

Aug 2021
ECOL INDIC

Soundscapes are increasingly used as innovative entry doors in environmental studies. Facing huge libraries of sound files which cannot be processed manually, acoustic indices provide an overview to the information contained in them, as well as to allow for automatic processing. Studies dealing with such indices have, however, focused more on specific topics or indices than on the overall characteristics of the soundscapes they were analyzing. The aim of this paper is to propose a holistic approach to soundscapes. Our hypothesis is that sufficient number and variety of indices can help frame the characteristics of sound environments and that the use of clustering algorithms allows us to group them in families and study the distribution of those across space and time, revealing a geography that will not necessarily coincide with the obvious landscape/visual geography. To demonstrate this point, we have run indices analysis and classification on a soundscapes database recorded in the Sonoran Desert region (Southeastern Arizona, USA). The results show that sound indices reveal temporal variations and patterns of soundscapes and point out to sometimes surprising similarities between otherwise different environments. As sound indices capture a wealth of information which characterizes the environment at a given place and time, they could be used as proxies to continuous monitoring without having to store extreme amounts of data.

It Often Howls More than It Chugs: Wind versus Ship Noise Under Water in Australia’s Maritime Regions

Article

Full-text available

Apr 2021

Marine soundscapes consist of cumulative contributions by diverse sources of sound grouped into: physical (e.g., wind), biological (e.g., fish), and anthropogenic (e.g., shipping)—each with unique spatial, temporal, and frequency characteristics. In terms of anthropophony, shipping has been found to be the greatest (ubiquitous and continuous) contributor of low-frequency underwater noise in several northern hemisphere soundscapes. Our aim was to develop a model for ship noise in Australian waters, which could be used by industry and government to manage marine zones, their usage, stressors, and potential impacts. We also modelled wind noise under water to provide context to the contribution of ship noise. The models were validated with underwater recordings from 25 sites. As expected, there was good congruence when shipping or wind were the dominant sources. However, there was less agreement when other anthropogenic or biological sources were present (i.e., primarily marine seismic surveying and whales). Off Australia, pristine marine soundscapes (based on the dominance of natural, biological and physical sound) remain, in particular, near offshore reefs and islands. Strong wind noise dominates along the southern Australian coast. Underwater shipping noise dominates only in certain areas, along the eastern seaboard and on the northwest shelf, close to shipping lanes.

What does resilience sound like? Coral reef and dry forest acoustic communities respond differently to Hurricane Maria

Article

Full-text available

Apr 2021
ECOL INDIC

Disturbance regimes and biodiversity—two factors that govern the stability of ecosystems—are changing rapidlydue to anthropogenic forces including climate change. Determining whether ecosystems retain their structure and function through intensifying disturbance regimes is an urgent task. However, quantitatively assessing the resilience of natural systems is a complex and challenging endeavor, especially for animal communities, for which datasets around disturbance events are scarce. Here, we apply an emerging remote sensing tech-nology—the recording and analysis of soundscapes—to quantify the resilience of Puerto Rican coral reef and dry forest animal communities in relation to Hurricane Maria, which struck the island in September 2017. Using recordings collected between March 2017 and January 2018 at three terrestrial and three marine sites, we measured three dimensions of resilience—the magnitude of the impacts (resistance), the spatial pattern of the impacts (heterogeneity), and the diversity and timeline of functional responses (recovery)—across eight sound types representing different broad taxonomic groups. While the coral reef communities exhibited high resistance to the storm, all sound types within the dry forest were significantly impacted, with two of the three insect choruses and bird vocalizations at dawn declining approximately 50% in the weeks following Hurricane Maria. The mid-frequency insect sound type returned to pre-storm levels after 56 days, while bird vocalizations returned after 67 days, though seasonal and lunar patterns underscored the importance of long-term data for accurately measuring trajectories of recovery. This study demonstrates that soundscape methodologies can help to quantify elusive dimensions of animal community resilience in order to better understand how biodiversity and ecosystem functioning will change under novel disturbance regimes.

Mapping ecoacoustic hot spots and moments of biodiversity to inform conservation and urban planning

Article

Full-text available

Jul 2021
ECOL INDIC

As the rate of urbanisation continues to increase, widespread habitat clearing within peri-urban landscapes contributes to significant environmental impacts, including loss of biological diversity. Acoustic recording has recently been identified as an effective tool for monitoring biodiversity and ecosystem health. With increasing pressure from urbanisation, it is critical that spatial and temporal variability in biodiversity is mapped across future development sites to enable sound decision-making and to deliver ecological urban design outcomes. This study used ecoacoustic monitoring to map biodiversity patterns in space and time to identify hot spots and hot moments of biodiversity activity across a peri-urban landscape in south-east Queensland, Australia. In this study, a hot spot represents an increase in acoustic activity at a given spatial location, whereas hot moments represent an increase in acoustic activity at a given time point. An acoustic index (Acoustic Complexity Index, ACI) was used as a proxy for biodiversity and visualised through spatial interpolation. The acoustic data were statistically modelled using Boosted Regression Trees (BRT). This approach enabled predictors related to acoustic complexity to be identified, including vegetation and landform. Results of this study have shown that ecoacoustic data can be used to map hot spots and hot moments of biodiversity and support more informed conservation decision-making in future urban planning frameworks, to avoid or mitigate negative impacts on biodiversity.

Silent winters and rock-and-roll summers: The long-term effects of changing oceans on marine fish vocalization

Article

Full-text available

Jun 2021
ECOL INDIC

The analysis of temporal trends and spatial patterns of marine sounds can provide crucial insights to assess the abundance, distribution, and behavior of fishes and of many other species. However, data on species-specific temporal and seasonal changes are still extremely limited. We report here the result of the longest recording ever conducted (five years, from 2014 to 2018) on fish vocalization. Findings from the Eastern Taiwan Strait (ETS) revealed a periodic fish chorusing pattern, with peaks in summer and almost complete silence, for ~2 months, during winter. Chorusing pattern was influenced by abiotic parameters, including temperature, tides and moon phase. We also report, for the first time, that extreme weather events (e.g., typhoons, storms with sediment resuspension) caused the cessation of the chorusing. The chorusing pattern explored in this long-term study provides important baseline data to understand the impact of climate change and of climate-driven extreme/episodic events on the phenology of fishes; this work also provides evidence that changes in the ambient conditions might significantly alter the phenology of vocalizing marine species.

Ecoacoustics and Multispecies Semiosis: Naming, Semantics, Semiotic Characteristics, and Competencies

Article

Full-text available

Apr 2021

Biosemiotics to date has focused on the exchange of signals between organisms, in line with bioacoustics; consideration of the wider acoustic environment as a semiotic medium is under-developed. The nascent discipline of ecoacoustics, that investigates the role of environmental sound in ecological processes and dynamics, fills this gap. In this paper we introduce key ecoacoustic terminology and concepts in order to highlight the value of ecoacoustics as a discipline in which to conceptualise and study intra- and interspecies semiosis. We stress the inherently subjective nature of all sensory scapes (vivo-, land-, vibro- and soundscapes) and propose that they should always bear an organismic attribution. Key terms to describe the sources (geophony, biophony, anthropophony, technophony) and scales (sonotopes, soundtopes, sonotones) of soundscapes are described. We introduce epithets for soundscapes to point to the degree to which the global environment is implicated in semiosis (latent, sensed and interpreted soundscapes); terms for describing key ecological structures and processes (acoustic community, acoustic habitat, ecoacoustic events) and examples of ecoacoustic events (choruses and noise) are described. The acoustic eco-field is recognized as the semiotic model that enables soniferous species to intercept core resources like food, safety and roosting places. We note that whilst ecoacoustics to date has focused on the critical task of the development of metrics for application in conservation and biodiversity assessment, these can be enriched by advancing conceptual and theoretical foundations. Finally, the mutual value of integrating ecoacoustic and biosemiotics perspectives is considered.

Changes on soundscapes reveal impacts of wildfires in the fauna of a Brazilian savanna

Article

Jan 2021
SCI TOTAL ENVIRON

Wildfire is a natural process in Brazilian savannas, but human activities alter fire regimes and threaten biodiversity. In this study, weused an ecoacoustics approach to assess fauna responses and recovery after wildfire in a Brazilian savanna. Six passive acoustic monitoring devices were used to record soundscapes before and after a wildfire a at burned and non-burned sites for one year and one month (September 2012 to September 2013). Power Spectral Density and the Acoustic Complexity Index were used to track biophony. Before the fire, the two sites had similar biophonic patterns (PSD: T=1136, Z=1.52, P=0.12; ACI: T=1117, Z=1.10 , P=0.26) and soniferous species richness (Site 1=52 and Site 2=49). However, in the first two sessions of recordings after the fire, biophony became higher at the burned site during the day (PSD: T=211 and 233; Z=4.13 and 6.41; ACI: T=120 and 469, Z=5.14 and 7.07; all P<0.00). During the night, biophony was usually higher at the non-burned site until May 2013 (PSD: T=0 to 453; Z=3.30 to 5.90; ACI: T=333 to 491, Z=3.80 to 4.93; all P<0.00). Biophony became similar (P=0.17 to 0.38) at the two sites or higher (P=0.00 to 0.01) at the burned site from July to September 2013 (PSD: T=55 to 1167; Z=1.35 to 6.89; ACI: T=719 to 1365, Z=0.87 to 3.04). After the fire, a reduction of soniferous species at the burned site was observed for insects and bats. Both biophonic activity and soniferous species showed a tendency to recover one year after the fire, but there were still less species in September 2013 (non-burned=43 and burned=37) when compared to September 2012 at both sites (Site 1= 52 and Site 2=49). Our results showed that changes in the natural regimes of fire can negatively impact the biodiversity and reinforce the need for monitoring protocols and inspection of wildfires.

Vegetation structure and temporality influence the dominance, diversity, and composition of forest acoustic communities

Article

Feb 2021
FOREST ECOL MANAG

Bioacoustic methods analyze sounds to monitor wildlife in forests, providing novel perspectives to understand the relationship between forest vegetation structure and wildlife species. Bioacoustic studies differ from traditional field surveys that are often more visual and require work in the daytime. A sampling of acoustic signals is possible to explore the diurnal variation of the forest ecosystem. Normalized difference soundscape index (NDSI), acoustic diversity index (ADI), and power spectral density (PSD) were chosen as acoustic indices to quantify the dominance, diversity, and composition of the biophony of forest settings. Biophony was recorded in ten south subtropical evergreen broad-leaved forest sites in Shenzhen, China. Composition structure (species richness), horizontal structure (vegetation density and canopy cover), and vertical structure (tree height diversity and each layer height) were used to evaluate the structure of vegetation. Linear Mixed Models (LMMs) were applied to examine the effects of different vegetation structures on biophony between day and night. The relationships between various biophonic frequency bands and vegetation structural variables during day and night were estimated by redundancy analysis (RDA). Results showed that different sound frequencies and vocalization behavior of vocalizing species determine the variance between the forest sound environment during day and night. Forest canopy and understory have a significant influence on biophonic diversity and dominance separately. The vocalizing species' preferences for different habitats were affected by the same vegetation structure variables across diurnal variation. Canopy cover and understory species richness had a significant positive effect on low-frequency biophony, and tree height diversity was found to have a significant positive impact on high-frequency biophony. Finally, tree height diversity was the core variable in the forest acoustic environment, and higher tree height diversity resulted in a more dominant and diverse biophony. This study shows the potential of bioacoustic methods to reveal the day-night dynamics of vocalizing species, using easily measured acoustic variables that can help with the timely evaluation of potential impacts of vegetation structure on forest animal communities.

Passive acoustic monitoring as a potential tool to survey animal and ecosystem processes in freshwater environments

Article

Jun 2019

Biodiversity in freshwater habitats is decreasing faster than in any other type of environment, mostly as a result of human activities. Monitoring these losses can help guide mitigation efforts. In most studies, sampling strategies predominantly rely on collecting animal and vegetal specimens. Although these techniques produce valuable data, they are invasive, time‐consuming and typically permit only limited spatial and temporal replication. There is need for the development of complementary methods. As observed in other ecosystems, freshwater environments host animals that emit sounds, either to communicate or as a by‐product of their activity. The main freshwater soniferous groups are amphibians, fish, and macroinvertebrates (mainly Coleoptera and Hemiptera, but also some Decapoda, Odonata, and Trichoptera). Biophysical processes such as flow or sediment transport also produce sounds, as well as human activities within aquatic ecosystems. Such animals and processes can be recorded, remotely and autonomously, and provide information on local diversity and ecosystem health. Passive acoustic monitoring (PAM) is an emerging method already deployed in terrestrial environments that uses sounds to survey environments. Key advantages of PAM are its non‐invasive nature, as well as its ability to record autonomously and over long timescales. All these research topics are the main aims of ecoacoustics, a new scientific discipline investigating the ecological role of sounds. In this paper, we review the sources of sounds present in freshwater environments. We then underline areas of research in which PAM may be helpful emphasising the role of PAM for the development of ecoacoustics. Finally, we present methods used to record and analyse sounds in those environments. Passive acoustics represents a potentially revolutionary development in freshwater ecology, enabling continuous monitoring of dynamic bio‐physical processes to inform conservation practitioners and managers.

A novel frog chorusing recognition method with acoustic indices and machine learning

Article

Jun 2021
FUTURE GENER COMP SY

This study aims to recognise frog choruses using false-colour spectrograms and machine learning algorithms with acoustic indices. This can be a useful solution for improving the efficiency of long-term acoustic monitoring. Acid frogs, our target species, are a group of endemic frogs that are particularly sensitive to habitat change and competition from other species. The Wallum Sedgefrog (Litoria olongburensis) is the most threatened acid frog species facing habitat loss and degradation across much of their distribution, in addition to further pressures associated with anecdotally-recognised competition from their sibling species, the Eastern Sedgefrogs (Litoria fallax). Monitoring the calling behaviours of these two species is essential for informing L. olongburensis management and protection, and for obtaining ecological information about the process and implications of their competition. Considering the cryptic nature of L. olongburensis and the sensitivity of their habitat to human disturbance, passive acoustic monitoring is a suitable method for monitoring this species. However, manually processing this overwhelmingly large quantities of acoustic data collected is time-consuming and not feasible in the long-term. Therefore, there is a high demand for automated acoustic recognition methods to efficiently search long-duration recordings and identify target species. In this study, we propose a two-step scheme for quickly identifying frog choruses, which is first narrowing down the search scope by inspecting long-duration false-colour spectrograms and then recognising target acoustic signals using machine learning and acoustic indices. This method is efficient, time-saving and general, which means it can easily adopted to other species. Our research also provides insights on how to choose acoustic features that efficiently recognise species from larger scale field-collected recordings. The experimental results show that these techniques are useful in identifying choruses of the two competitive frog species with an accuracy of 76.7% on identifying four acoustic patterns (whether the two species occurred).

The Tallgrass Prairie Soundscape; Employing an Ecoacoustic Approach to Understand Grassland Response to Prescribed Burns and the Spatial and Temporal Patterns of Nechrophilous Invertebrate Communities

Thesis

Full-text available

Jul 2018

Sarah Dodgin

Tallgrass prairies are rapidly vanishing biodiversity hotspots for native and endemic species, yet little is known regarding how spatial and temporal variation of prairie soundscapes relates to seasonal changes, disturbance patterns and biological communities. Ecoacoustics, the study of environmental sounds using passive acoustics as a non-invasive tool for investigating ecological complexity, allows for long-term data to be captured without disrupting biological communities. Two studies were carried out by employing ecoacoustic methodology to study grassland carrion food webs and to capture the phenology of a grassland soundscape following a prescribed burn. Both studies were conducted at the Nature Conservancy’s Tallgrass Prairie Preserve (36°50’N, 96°25’W) and used six acoustic indices to quantify the ratio of technophony to biophony, acoustic complexity, diversity, evenness, entropy, and biological acoustic diversity from over 70,000 sound recordings. Acoustic index values were used to determine the relationship between Nicrophorus burying beetle species composition and the prairie soundscape (Chapter 1) and to determine if prescribed burning changes the composition of the soundscape over time (Chapter 2). In Chapter 1, I found that associations between Nicrophorus burying beetles and the soundscape were unique to particular species, acoustic indices and times of day. For example, N. americanus trap rates showed a positive correlation to areas of increased acoustic complexity specifically at dawn. In addition to positive associations with the soundscape, we found that N. marginatus was consistently negatively correlated to higher levels of biophony, while N. tomentosus was consistently positively correlated to places with higher levels of biophony. Although reproduction of all species examined is dependent upon securing small carrion for reproduction, I found that known habitat and activity segregation of five Nicrophorus beetle species may be reflective of the soundscape. Finally, I show that favorable habitat for a critically endangered necrophilous insect, the American burying beetle (Nicrophorus americanus) can be identified by the acoustic signature extracted from a short temporal window of its grassland ecosystem soundscape. Using the same suite of acoustic indices from Chapter 1, in Chapter 2 I examined acoustic recordings at a much larger time scale to determine distinctive acoustic events driven by biophony and geophony across a 23-week period. In addition to examining acoustic changes over time, I examined differences between 11 burned and unburned pastures. Results from this study indicate that prescribed burning does alter the soundscape, especially early in the post-burn period, but the effects are ameliorated by a significant increase in biophony as the growing and breeding season progressed into the warmer summer months. Both studies demonstrate that passive acoustic recording is a reliable method to assess relationships to acoustic communities over space and time.

Acoustic auto-encoders for biodiversity assessment

Article

Mar 2021
ECOL INFORM

Continuous audio recordings are playing an ever more important role in conservation and biodiversity monitoring, however, listening to these recordings is often infeasible, as they can be thousands of hours long. Automating analysis using machine learning algorithms requires a feature representation. In this paper we propose a technique for learning a general feature representation from unlabelled audio using auto-encoders, which can be used for analysing environmental audio on a small timescale. We start by segmenting the audio data into non-overlapping 1-s long chunks and generating audio spectrograms. These audio spectrograms are then used to train a basic auto-encoder, with the output of the encoder network being used to generate the feature representation. We have found that at a 1-s timescale, our feature representation offers marginal improvements over “acoustic indices”, a common representation for analysing environmental audio.

Application of a sample space for the characterization of shaded coffee plantation soundscape

Article

Jun 2020
ECOL INFORM

J. Almeira

The plot of the frequencies that build soundscapes (power spectrum) has been used to show some of their distinctive characteristics. The application of a discretized sample space is proposed to describe, in a concise manner, the contribution of different frequency signals in a soundscape on a yearly scale. A sample space composed of frequency and intensity combinations was used to describe the shapes of power spectrums and their recurrence. The number of elements of the sample space was set so that each element had a low probability of being found in random samples. In this way, the statistical confidence in the occurrence and recurrence of the elements is increased, making it possible to validate traits in the soundscape. According to their occurrence, it was established that there are “base”, “temporary” and “sporadic” combinations of frequency-intensity. When the relative frequencies of the frequency-intensity combinations were plotted versus the number of analyzed power spectrums, it was observed that few combinations predominate in the soundscape. Further, the distribution of the relative frequencies of the combinations tends to stabilize with time; a potential function described the relative frequency of the combinations. It was found that a logarithmic accumulation curve described the relationship between the analyzed power spectrums and the detected combinations in each of the proposed frequency sections; such a function was useful to validate the sampling method.

Soundscape dynamics of a cold protected forest: dominance of aircraft noise

Article

Full-text available

Feb 2022
LANDSCAPE ECOL

Context One mainstay of soundscape ecology is to understand acoustic pattern changes, in particular the relative balance between biophony (biotic sounds), geophony (abiotic sounds), and anthropophony (human-related sounds). However, little research has been pursued to automatically track these three components. Objectives Here, we introduce a 15-year program that aims at estimating soundscape dynamics in relation to possible land use and climate change. We address the relative prevalence patterns of these components during the first year of recording. Methods Using four recorders, we monitored the soundscape of a large coniferous Alpine forest at the France-Switzerland border. We trained an artificial neural network (ANN) with mel frequency cepstral coefficients to systematically detect the occurrence of silence and sounds coming from birds, mammals, insects (biophony), rain (geophony), wind (geophony), and aircraft (anthropophony). Results The ANN satisfyingly classified each sound type. The soundscape was dominated by anthropophony (75% of all files), followed by geophony (57%), biophony (43%), and silence (14%). The classification revealed expected phenologies for biophony and geophony and a co-occurrence of biophony and anthropophony. Silence was rare and mostly limited to night time. Conclusions It was possible to track the main soundscape components in order to empirically estimate their relative prevalence across seasons. This analysis reveals that anthropogenic noise is a major component of the soundscape of protected habitats, which can dramatically impact local animal behavior and ecology.

Classification and regression trees: A powerful yet simple technique for ecological data analysis

Article

Full-text available

Jan 2002
ECOLOGY

Atlas of the vegetation of madagascar

Article

Full-text available

Jan 2007

Madagascar is home to more than 10 000 plant species, 80% of which occur nowhere else in the world. With natural vegetation ranging from rainforest to unique spiny forest, Madagascar’s range of plant diversity makes it one of the world's most important biodiversity hotspots. In common with many other tropical countries, the flora of Madagascar is extremely threatened not only by habitat destruction for agriculture, fuelwood, building materials and so on, but also, in the case of certain species, by over-collection for the horticultural trade. The CEPF Madagascar Vegetation Mapping Project is a three-year project (2003–2006), funded by the Critical Ecosystem Partnership Fund (CEPF) and managed jointly by The Royal Botanic Gardens, Kew, Missouri Botanical Garden, and Conservation International’s Center for Applied Biodiversity Science. The project is innovative in a number of ways. It employs state-of-the art remote sensing technology and methodologies to delimit Madagascar’s vegetation. It represents an all-inclusive collaboration between specialists from a wide range of botanical and conservation institutions, which has ensured the most thoroughly ground-truthed vegetation map ever compiled for Madagascar. Finally, through a series of workshops, it incorporates detailed consultations with the conservation community to ensure that the final products are of maximum relevance and utility to conservation planners and managers. An accurate and updated vegetation map is imperative for conservation planning and natural resource management in Madagascar. It is also essential that the data on which such a map is based be made freely available, so that conservation organisations, government departments, academic institutions and other stakeholders can use them as an up-to-date standard dataset on which to base their activities. The electronic version of this atlas is available on Kew’s website (www.vegmad.org), and local experts were invited to continually improve and update the map. In order for a vegetation map to fulfil its intended role it must accurately delimit areas with various vegetation types as they currently exist, and assign those areas to objective categories that can be easily recognised in the field and that reliably reflect fundamental biological differences (primarily structural features, for example, physiognomy). Madagascar is becoming increasingly aware of the need to protect its biodiversity. The most immediate use of this vegetation map in conservation is likely to be by protected area managers who wish to understand the flora of their designated areas. It will also provide a valuable baseline for monitoring longer-term changes in vegetation inside and outside protected areas. However, Madagascar also provides an exceptionally high rate of species discovery and description, and this atlas will be used by field biologists attempting to identify potential sampling sites for biodiversity surveys, which will in turn yield data that is critical for biogeographic research and conservation planning. At the 2003 World Parks Congress, Madagascar’s President Marc Ravalomanana emphasised his country’s commitment to conservation by announcing its intent to triple the size of its existing protected area network. This admirable effort to prevent the extinction of many of Madagascar’s endemic species has become known as the ‘Durban Vision’. In order to ensure effective preservation of Madagascar’s biodiversity, the identification of sites for these new protected areas should follow a systematic process. A recent workshop on systematic conservation planning (November 2005, Antananarivo) highlighted the importance of using habitat types and indicators of habitat quality in addition to species distribution data when conducting conservation prioritisation analyses, concluding that this is the best way to produce robust conservation solutions. Because only a small proportion of Madagascar’s species have had their distributions documented, the vegetation types identified by this mapping project are good surrogates for habitat diversity and for the majority of the biota, which is so little known. In addition, conservation practitioners, including NGOs and donors, need information on trends in natural vegetation cover and quality in order to assess the outcomes of their conservation work. The Convention on Biological Diversity includes trends in the extent of habitats among its headline indicators for tracking progress towards the 2010 target (SBSTTA, 2004). The immediate focus of the Durban Vision group will be on establishing new protected areas (map 1) in remaining native vegetation, although subsequent attention could productively turn to managing that vegetation, and the habitat quality categories in the atlas provide valuable information. The atlas also provides important up-to-date information on native vegetation cover and quality, which maximises its potential to aid planning for future habitat restoration activities.

Soundscape Characteristics Of An Environment A New Ecological Indicator Of Ecosystem Health

Chapter

Full-text available

Dec 2007

Determinants of group size in primates: the importance of travel costs. In: Boinski S,Garber PA, editors.On the move: how and why animals travel in groups

Article

Full-text available

Assessment of ecosystem biodiversity by acoustic diversity indices

Article

Full-text available

May 2001
J ACOUST SOC AM

Assessment of ecosystem biodiversity by measurement of acoustic diversity was explored [B. L. Krause, Explorers J., Winter, 156–160 (1993)]. Specific acoustic indices (e.g., based on frequency spectrum) were developed and correlated with standard diversity indices (e.g., standard species abundance indices). Necessary technological infrastructures and analytic processes to measure acoustic dynamics of ecological biodiversity were explored. An automated web‐based infrastructure capable of capturing, processing, and relaying real‐time field measurements from multiple ecosystems to desktop and home computers was developed, tested, and implemented. Key infrastructure components were remote field instrumentation, remote computer processing, wireless digital relay instrumentation, Internet server, and automation, relational database, and website software. A dynamic digital library of ecological acoustic samples, correlated ecosystem attributes, and acoustic analysis methodologies was established. Library resources, including digital sound files captured from ecosystems, were made available to researchers and the public over the Internet [N. Metzger and M. Blumenthal, Realizing Info. Future, NAP, 113–119 (1994)]. Indices of acoustic ecosystem diversity were refined through application on existing digital ecosystem sound recordings and digital sounds captured from multiple ecosystems. The performance of these indices was compared to standard biodiversity indices applied to the same ecosystems.

The classification of natural and anthropogenic vegetation in Madagascar

Chapter

Full-text available

Jan 1997

Bioacoustics: Habitat Ambience & Ecological Balance

Article

Full-text available

Dec 1987

Bernie Krause

The first iteration of the niche hypothesis and the foundational concepts for the field of Soundscape Ecology.

Anthropogenic sound and marine mammal health: Measures of the nervous and immune systems before and after intense sound exposure

Article

Full-text available

Jul 2004

Anthropogenic sound is a potential stressor for marine mammals that may affect health, as has been demonstrated in other mammals. Therefore, we have initiated investigations on the effects of intense underwater sounds on nervous system activation and immune function in marine mammals. Blood samples were obtained before and after sound exposures (single underwater impulsive sounds (up to 200 kPa) produced from a seismic water gun and (or) single pure tones (up to 201 dB re 1 µPa) resembling sonar "pings" from a white whale, Delphinapterus leucas, and a bottlenose dolphin, Tursiops truncatus, to measure neural-immune parameters. Norepinephrine, epinephrine, and dopamine levels increased with increasing sound levels and were significantly higher after high-level sound exposures (>100 kPa) compared with low-level sound exposures (100 kPa) qu'après une exposition à un son de basse intensité (

Interplay of Phenology and Reproduction in Ring-Tailed Lemurs: Implications for Ring-Tailed Lemur Conservation

Article

Full-text available

Apr 1998
FOLIA PRIMATOL

Michelle Sauther

Data are presented on ring-tailed lemur feeding ecology and resource use at the Beza Mahafaly Special Reserve in southwestern Madagascar. The phenological availability of food resources was sampled monthly from 199 trees and 31 species. Results indicate that Lemur catta feeding ecology is finely tuned to the seasonal nature of specific food resources. Key species provide important food items during critical periods of the reproductive cycle. During a drought year, mortality for mothers and infants increased dramatically, providing indirect evidence that this species is highly dependent on the phenological reliability of food resources. These results indicate that in such highly seasonal habitats, the loss of any key species could have enormous impact on ring-tailed lemur demography and survival.

A toolbox for animal call recognition

Article

Full-text available

Jun 2012
BIOACOUSTICS

Monitoring the natural environment is increasingly important as habit degradation and climate change reduce the world's biodiversity. We have developed software tools and applications to assist ecologists with the collection and analysis of acoustic data at large spatial and temporal scales. One of our key objectives is automated animal call recognition, and our approach has three novel attributes. First, we work with raw environmental audio, contaminated by noise and artefacts and containing calls that vary greatly in volume depending on the animal's proximity to the microphone. Second, initial experimentation suggested that no single recognizer could deal with the enormous variety of calls. Therefore, we developed a toolbox of generic recognizers to extract invariant features for each call type. Third, many species are cryptic and offer little data with which to train a recognizer. Many popular machine learning methods require large volumes of training and validation data and considerable time and expertise to prepare. Consequently we adopt bootstrap techniques that can be initiated with little data and refined subsequently. In this paper, we describe our recognition tools and present results for real ecological problems.

Density as a Misleading Indicator of Habitat Quality

Article

Full-text available

Oct 1983

Beatrice Van Horne

Current methods of evaluating wildlife habitat for management,purposes can be arranged in a hierarchy of increasing generality. The most general level is evaluation of wildlife habitat for entire com- munities on the basis of inferences drawn from vegetational structure. At the base of the hierarchy the high resolution studies, upon which accuracy at the higher hierarchical levels depends, usually assume that habitat quality for a species is positively correlated with the density of the species. If habitat quality for a wildlife species is a measure of the importance of habitat type in maintaining a particular species, habitat quality should be defined in terms of the survival and production characteristics, as well as the density, of the species occupying that habitat. Situations in which habitat quality thus defined is not expected to be positively

Global land cover classi cation at 1km spatial resolution using a classification tree approach

Article

Full-text available

Apr 2000
INT J REMOTE SENS

This paper on reports the production of a 1 km spatial resolution land cover classification using data for 1992-1993 from the Advanced Very High Resolution Radiometer (AVHRR). This map will be included as an at-launch product of the Moderate Resolution Imaging Spectroradiometer (MODIS) to serve as an input for several algorithms requiring knowledge of land cover type. The methodology was derived from a similar effort to create a product at 8 km spatial resolution, where high resolution data sets were interpreted in order to derive a coarse-resolution training data set. A set of 37 294 x 1 km pixels was used within a hierarchical tree structure to classify the AVHRR data into 12 classes. The approach taken involved a hierarchy of pair-wise class trees where a logic based on vegetation form was applied until all classes were depicted. Multitemporal AVHRR metrics were used to predict class memberships. Minimum annual red reflectance, peak annual Normalized Difference Vegetation Index (NDVI), and minimum channel three brightness temperature were among the most used metrics. Depictions of forests and woodlands, and areas of mechanized agriculture are in general agreement with other sources of information, while classes such as low biomass agriculture and high-latitude broadleaf forest are not. Comparisons of the final product with regional digital land cover maps derived from high-resolution remotely sensed data reveal general agreement, except for apparently poor depictions of temperate pastures within areas of agriculture. Distinguishing between forest and non-forest was achieved with agreements ranging from 81 to 92% for these regional subsets. The agreements for all classes varied from an average of 65% when viewing all pixels to an average of 82% when viewing only those 1 km pixels consisting of greater than 90% one class within the high-resolution data sets.

How Far to the Nearest Road?

Article

Full-text available

Apr 2003
FRONT ECOL ENVIRON

Ecological impacts from roads may be the rule rather than the exception in most of the conterminous United States. We measured the proportion of land area that was located within nine distances from the nearest road of any type, and mapped the results for 164 ecoregions and 2108 watersheds nationwide. Overall, 20% of the total land area was within 127 m of a road, and the proportion increased rapidly with distance, so that 83% was within 1061 m of a road, and only 3% was more than 5176 m away. For forest land area only, the proportions differed by less than 2% for all distances. Regions with more than 60% of their total land area within 382 m of a road may be at greatest risk of cumulative ecological impacts from roads. These regions include nearly all coastal zones, as well as substantial portions of the southeast US and the basins of the Ohio, Brazos, Colorado, Sacramento, and San Joaquin Rivers.

Soundscape Ecology: The Science of Sound in the Landscape

Article

Full-text available

Mar 2011
BIOSCIENCE

This article presents a unifying theory of soundscape ecology, which brings the idea of the soundscape—the collection of sounds that emanate from landscapes—into a research and application focus. Our conceptual framework of soundscape ecology is based on the causes and consequences of biological (biophony), geophysical (geophony), and human-produced (anthrophony) sounds. We argue that soundscape ecology shares many parallels with landscape ecology, and it should therefore be considered a branch of this maturing field. We propose a research agenda for soundscape ecology that includes six areas: (1) measurement and analytical challenges, (2) spatial-temporal dynamics, (3) soundscape linkage to environmental covariates, (4) human impacts on the soundscape, (5) soundscape impacts on humans, and (6) soundscape impacts on ecosystems. We present case studies that illustrate different approaches to understanding soundscape dynamics. Because soundscapes are our auditory link to nature, we also argue for their protection, using the knowledge of how sounds are produced by the environment and humans.

A near-real time forest-cover map of Madagascar derived from SPOT-4 VEGETATION data

Article

Full-text available

Nov 2000
INT J REMOTE SENS

Using SPOT-4 VEGETATION data for near-real time mapping is new. In this Letter, a robust technique for cloud decontamination of the ten-day composites is presented. A forest-cover map of Madagascar is derived from monthly images from October 1998 to September 1999 with a user's accuracy of 87.8%.

Distribution of Migratory Landbirds Along the Northern Lake Huron Shoreline

Article

Full-text available

Aug 2011

The distribution of landbirds during migration in forested landscapes of eastern North America is poorly known. We describe (1) the distribution of landbirds in northern white cedar (Thuja occidentalis) dominated forests as a function of distance from northern Lake Huron in Michigan during spring and autumn migration, and (2) discuss factors that may affect the distribution of these migrants. Both long- and short-distance migrants in spring and fall were concentrated within 0.4 km of the Lake Huron shoreline. This pattern was particularly pronounced during spring when aquatic-hatched insects such as midges and their predators (e.g., spiders) are most common and occur in largest numbers near the shoreline. Both long- and short-distance migrant abundance was associated with midge abundance, after controlling for date, during spring migration but not during fall migration. Migrants may concentrate near the shoreline because of the barrier effect of Lake Huron and relatively abundant food resources, especially during spring migration. Terrestrial habitats adjacent to bodies of water, where aquatic-dependent invertebrates are relatively abundant may provide important stopover sites for landbird migrants. Our results suggest coastal areas within the Great Lakes region provide critical stopover habitat for landbird migrants and should be a focus of conservation efforts, especially given the increasing development pressure that threatens these areas.

Fifty Years of Deforestation and Forest Fragmentation in Madagascar

Article

Full-text available

Dec 2007
ENVIRON CONSERV

Tropical deforestation is a key contributor to species extinction and climate change, yet the extent of tropical forests and their rate of destruction and degradation through fragmentation remain poorly known. Madagascar's forests are among the most biologically rich and unique in the world but, in spite of longstanding concern about their destruction, past estimates of forest cover and deforestation have varied widely. Analysis of aerial photographs (c. 1953) and Landsat images (c. 1973, c. 1990 and c. 2000) indicates that forest cover decreased by almost 40% from the 1950s to c. 2000, with a reduction in 'core forest' > 1 km from a non-forest edge of almost 80%. This forest destruction and degradation threaten thousands of species with extinction. Country-wide coverage of high-resolution validated forest cover and deforestation data enables the precise monitoring of trends in habitat extent and fragmentation critical for assessment of species' conservation status.

Sources, Sinks, and Population Regulation

Article

Full-text available

Nov 1988

H. Ronald Pulliam

Animal and plant populations often occupy a variety of local areas and may experience different local birth and death rates in different areas. When this occurs, reproductive surpluses from productive source habitats may maintain populations in sink habitats, where local reproductive success fails to keep pace with local mortality. For animals with active habitat selection, an equilibrium with both source and sink habitats occupied can be both ecologically and evolutionarily stable. If the surplus population of the source is large and the per capita deficit in the sink is small, only a small fraction of the total population will occur in areas where local reproduction is sufficient to compensate for local mortality. In this sense, the realized niche may be larger than the fundamental niche. Consequently, the particular species assemblage occupying any local study site may consist of a mixture of source and sink populations and may be as much or more influenced by the type and proximity of other habitats a...

Introduction to Distance Sampling: Estimating Abundance of Biological Populations

Book

Full-text available

Jan 2001

This book is available for purchase, The 1993 version is available on the page at http://distancesampling.org/whatisds.html

Monitoring flight calls of migrating birds from an oil platform in the northern Gulf of Mexico

Article

Full-text available

Aug 2007
J FIELD ORNITHOL

Millions of birds migrate across the Gulf of Mexico each year. However, most studies of migration in this region involve sampling onshore locations during the day, potentially underrepresenting the diversity and abundance of migrants passing the region. We evaluated a potential solution to this problem by recording the flight calls of passing migrants from an oil platform located southeast of the Alabama coast in the Gulf of Mexico. We detected 2762 calls during 30 nights from 9 September to 2 November 1999, and were able to identify 2329 calls to species. Flight calls by nine species of birds represented 23% of all identified calls. The greatest number of calls during one night (1017 calls) and during a 1-h period (257 calls) were recorded on 10 September. The greatest number of calls was recorded 8 h after sunset, with a secondary peak 2 h after sunset. The peak prior to sunrise may indicate the formation of flocks at dawn, and the peak after sunset may have been caused by the first wave of migrants reaching the platform. However, call counts varied extensively, with 98% of all calls recorded during 13 nights and 40% on a single night, possibly resulting from hourly and nightly differences in bird numbers aloft, atmospheric conditions, and artificial lighting conditions. Although recording on oil platforms can be difficult because of mechanical, wind, and wave noise, our results suggest great potential for describing the species composition of passing vocal migrants and the temporal patterns of flight-calling behavior if quiet recording locations can be found. Moreover, flight call monitoring could be a critically important tool for bird conservation in this region, given recent proposals to develop wind power and the potential bird mortality associated with such developments.

The Soundscape: Our Sonic Environment and the Tuning of the World

Book

Jan 1999

R. Murray Schafer

Ecological effects of snowmobiles

Article

Jan 1972
Can Field Nat

From space to species: Ecological applications for remote sensing

Article

Jan 2003
TRENDS ECOL EVOL

Random forests

Article

Jan 2001

Radar observations of bird migration over the Great Lakes

Article

Apr 2003
AUK

The Great Lakes and nearby agricultural midwestern United States together represent a geographical challenge to migratory land birds during flight and stopover. We explored large-scale migratory responses of land birds encountering the Great Lakes as revealed by weather surveillance radars (WSR-88D) and two smaller specialized radars. Those responses reveal comprehensive landscape- or regional-scale migratory patterns that would otherwise have been difficult to infer. Analysis of radar echoes showed birds crossed the Great Lakes in large numbers, although we also found evidence of birds avoiding lake crossing in some locations. Around dawn, birds over water in numerous locations frequently exhibited an increase in migratory height (dawn ascent) and often an accompanying reorientation toward nearest land if they were within ∼28 km of shore. Those behavioral responses to the Great Lakes influence the resulting distribution of birds stopping over in the intervening terrestrial landscapes.

Analysis and interpretation of variability in soundscape along an urban–rural gradient

Article

Dec 2011
LANDSCAPE URBAN PLAN

Urbanization has not only altered land cover types, but also changed acoustic environments to which animals must adapt or emigrate for effective communication. Although many studies have addressed the effects of urban noise on acoustic communication of vocal organisms, little work has been done to understand the acoustic characteristics and the interaction between biological and anthropogenic sounds across urban–rural landscapes. The objectives of this study were to investigate the spatial and temporal patterns of soundscape characteristics along an urban–rural gradient, and how soundscape properties are related to avian species community. We established 17 locations across the city of Lansing, Michigan from February to December 2006 to record environmental sounds. A multilevel regression model (MLRM) was used to understand the variability of acoustic power of biological and anthropogenic sounds (biophony and anthrophony) with temporal and spatial data structures. Canonical Correspondence Analysis (CCA) was employed to investigate how bird species respond along an environmental gradient.

Handbook for Acoustic Ecology

Article

Dec 1981

Barry Truax

The Great Animal Orchestra: Finding the Origins of Music in the World's Wild Places

Book

Mar 2012

Visualization of temporal change in soundscape power of a Michigan lake habitat over a 4-year period

Abstract

No full-text available