Quantitative Assessment of Grassland Quality: Acoustic Determination of Population Sizes of Orthopteran Indicator Species

Fischer, Franz Peter; Schulz, Ulrich; Schubert, Holger; Knapp, Petra; Schmoger, Marcus

doi:10.2307/2269442

Cited by 16 publications

(23 citation statements)

References 11 publications

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“…Density estimates based exclusively on acoustic data have already been presented for some taxonomic groups including insects (e.g. Fischer et al ., 1997), cetaceans (e.g. Marques et al ., 2009), birds (e.g.…”

Section: Discussionmentioning

confidence: 99%

“…Gardiner, Hill & Chesmore (2005) suggested acoustics-based distance sampling methods might be a plausible way to estimate grasshopper density [note that Fischer et al . (1997) had already presented such an example]. Some studies (e.g.…”

Section: Discussionmentioning

confidence: 99%

“…A similar approach, also requiring accounting for sex ratio and availability was presented by Fischer et al . (1997) to estimate grasshopper abundance.…”

Section: Estimating Density Using Fixed Passive Acoustics: Examplmentioning

confidence: 99%

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Estimating animal population density using passive acoustics

et al. 2012

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Reliable estimation of the size or density of wild animal populations is very important for effective wildlife management, conservation and ecology. Currently, the most widely used methods for obtaining such estimates involve either sighting animals from transect lines or some form of capture-recapture on marked or uniquely identifiable individuals. However, many species are difficult to sight, and cannot be easily marked or recaptured. Some of these species produce readily identifiable sounds, providing an opportunity to use passive acoustic data to estimate animal density. In addition, even for species for which other visually based methods are feasible, passive acoustic methods offer the potential for greater detection ranges in some environments (e.g. underwater or in dense forest), and hence potentially better precision. Automated data collection means that surveys can take place at times and in places where it would be too expensive or dangerous to send human observers.Here, we present an overview of animal density estimation using passive acoustic data, a relatively new and fast-developing field. We review the types of data and methodological approaches currently available to researchers and we provide a framework for acoustics-based density estimation, illustrated with examples from real-world case studies. We mention moving sensor platforms (e.g. towed acoustics), but then focus on methods involving sensors at fixed locations, particularly hydrophones to survey marine mammals, as acoustic-based density estimation research to date has been concentrated in this area. Primary among these are methods based on distance sampling and spatially explicit capture-recapture. The methods are also applicable to other aquatic and terrestrial sound-producing taxa.We conclude that, despite being in its infancy, density estimation based on passive acoustic data likely will become an important method for surveying a number of diverse taxa, such as sea mammals, fish, birds, amphibians, and insects, especially in situations where inferences are required over long periods of time. There is considerable work ahead, with several potentially fruitful research areas, including the development of (i) hardware and software for data acquisition, (ii) efficient, calibrated, automated detection and classification systems, and (iii) statistical approaches optimized for this application. Further, survey design will need to be developed, and research is needed on the acoustic behaviour of target species. Fundamental research on vocalization rates and group sizes, and the relation between these and other factors such as season or behaviour state, is critical. Evaluation of the methods under known density scenarios will be important for empirically validating the approaches presented here.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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Estimating animal population density using passive acoustics

et al. 2012

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“…Fischer et al (1997) used a conceptually similar approach, taking grasshoppers as indicators of conservation interest in dry grassland vegetation. Fischer et al (1997) used a conceptually similar approach, taking grasshoppers as indicators of conservation interest in dry grassland vegetation.…”

Section: Discussionmentioning

confidence: 99%

Prediction of Habitat Quality Using Ordination and Neural Networks

Ejrnæs¹,

Aude²,

Nygaard³

et al. 2002

Ecological Applications

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The development of an automatic classification model for prediction of conservation value is described. The classifier combines ordination and neural network (NN). The classifier was trained to predict the probability of a sample being of potential conservation interest. The neural network was trained on a priori classified data and used sample scores derived from ordination for prediction. The complexity of the NN classifier and the selection of the optimal ordination method were guided by cross-validation of a series of candidate models.The conservation value of a test data set was predicted by the NN classifier, and this classification was evaluated in terms of species richness, nativeness, rarity, and ␤ diversity. Finally, we evaluated the capability of the approach to handle new samples not included in the ordination. These samples were derived from habitats of threatened vascular plants, and they were all successfully predicted to be valuable.It is shown that the combination of ordination and neural networks successfully reproduces the a priori classification. It is further demonstrated on a test data set which the classifier discriminates with respect to traditional measures of conservation interest such as rarity, nativeness, and diversity. The developed method may be seen as a promising approach to assessment of biological integrity at the scale of plant communities, and further opportunities for its application are suggested.

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“…Within each study and control plot, we surveyed the Orthoptera for 12 min, at each of the four sides of the plots. Abundance of the male individuals of the Orthoptera species was estimated by acoustic sampling of the species-specific stridulation (Fischer et al 1997). The abundance of Miramella alpina, a species belonging to the family Catantopidae (Orthoptera: Acridoidea) whose stridulation is not audible to humans, was estimated by visual sampling.…”

Section: Orthoptera Samplingmentioning

confidence: 99%

Direct and indirect effects of ski run management on alpine Orthoptera

et al. 2011

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Alpine landscapes are heavily influenced by ski run management, which can have severe impacts on alpine biodiversity. To assess these impacts on alpine Orthoptera, we compared species richness and species abundance in 41 plot pairs on ski runs and adjacent off-slope control plots in three ski resorts in Austria and Germany. A mixed modelling approach was used to assess the impacts of ski run preparation, artificial snowmaking and environmental variables such as altitude, cover of dwarf shrubs and the application of fertilizer. Ski run plots showed a significantly lower species richness and number of individuals than control plots. Moreover, artificial snow led to a further decrease in species number. Hierarchical variance partitioning revealed that Orthoptera community composition is best predicted by environmental variables indirectly related to ski run management (fertilization, cover of dwarf shrubs) and to altitude. Only one out of five species significantly decreased in abundance after artificial snow-making. Other species were more sensitive to fertilizing and altitude. Dwarf shrubs were negatively associated with ski run management but positively associated with abundance of three species and species richness. Our data provide evidence for both direct and indirect consequences of ski runs and artificial snow-making on alpine Orthoptera. Overall, Orthoptera communities are suitable indicators for human-induced changes in alpine environments. In particular, a shift towards generalist species such as Chorthippus parallelus along with a decrease in typical alpine species gives cause for concern as this implies a homogenisation of biodiversity owing to ski run management.

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Quantitative Assessment of Grassland Quality: Acoustic Determination of Population Sizes of Orthopteran Indicator Species

Cited by 16 publications

References 11 publications

Estimating animal population density using passive acoustics

Estimating animal population density using passive acoustics

Prediction of Habitat Quality Using Ordination and Neural Networks

Direct and indirect effects of ski run management on alpine Orthoptera

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