Observations of the daytime boundary layer in deep alpine valleys

Peer reviewe

Observations of the daytime boundary layer in deep alpine valleys

Peer reviewe

Robust sound event detection in bioacoustic sensor networks

Bioacoustic sensors, sometimes known as autonomous recording units (ARUs), can record sounds of wildlife over long periods of time in scalable and minimally invasive ways. Deriving per-species abundance estimates from these sensors requires detection, classification, and quantification of animal vocalizations as individual acoustic events. Yet, variability in ambient noise, both over time and across sensors, hinders the reliability of current automated systems for sound event detection (SED), such as convolutional neural networks (CNN) in the time-frequency domain. In this article, we develop, benchmark, and combine several machine listening techniques to improve the generalizability of SED models across heterogeneous acoustic environments. As a case study, we consider the problem of detecting avian flight calls from a ten-hour recording of nocturnal bird migration, recorded by a network of six ARUs in the presence of heterogeneous background noise. Starting from a CNN yielding state-of-the-art accuracy on this task, we introduce two noise adaptation techniques, respectively integrating short-term (60 milliseconds) and long-term (30 minutes) context. First, we apply per-channel energy normalization (PCEN) in the time-frequency domain, which applies short-term automatic gain control to every subband in the mel-frequency spectrogram. Secondly, we replace the last dense layer in the network by a context-adaptive neural network (CA-NN) layer. Combining them yields state-of-the-art results that are unmatched by artificial data augmentation alone. We release a pre-trained version of our best performing system under the name of BirdVoxDetect, a ready-to-use detector of avian flight calls in field recordings.Comment: 32 pages, in English. Submitted to PLOS ONE journal in February 2019; revised August 2019; published October 201

Field validation of radar systems for monitoring bird migration

This is the author accepted manuscript. The final version is available from Wiley via the DOI in this record.Advances in information technology are increasing the use of radar as a tool to investigate and monitor bird migration movements. We set up a field campaign to compare and validate outputs from different radar systems. Here we compare the pattern of nocturnal bird migration movements recorded by four different radar systems at a site in southern Sweden. Within the range of the weather radar (WR) Ängelholm, we operated a "BirdScan" (BS) dedicated bird radar, a standard marine radar (MR), and a tracking radar (TR). The measures of nightly migration intensities, provided by three of the radars (WR, BS, MR), corresponded well with respect to the relative seasonal course of migration, while absolute migration intensity agreed reasonably only between WR and BS. Flight directions derived from WR, BS and TR corresponded very well, despite very different sample sizes. Estimated mean ground speeds differed among all four systems. The correspondence among systems was highest under clear sky conditions and at high altitudes. Synthesis and applications. While different radar systems can provide useful information on nocturnal bird migration, they have distinct strengths and weaknesses, and all require supporting data to allow for species level inference. Weather radars continuously detect avian biomass flows across a wide altitude band, making them a useful tool for monitoring and predictive applications at regional to continental scales that do not rely on resolving individuals. BirdScan and marine radar's strengths are in local and low altitude applications, such as collision risks with man-made structures and airport safety, although marine radars should not be trusted for absolute intensities of movement. In quantifying flight behaviour of individuals, TR is the most informative.We acknowledge the support provided by COST – European Cooperation in Science and Technology through the Action ES1305 ‘European Network for the Radar Surveillance of Animal Movement’ (ENRAM) in facilitating this collaboration. The study received financial support from Gyllenstierna Krapperup ́s Foundation and the Centre for Animal Movement Research (CAnMove) financed by a Linnaeus grant (349-2007-8690) from the Swedish Research Council and Lund University

Improving the efficiency and accuracy of nocturnal bird Surveys through equipment selection and partial automation

This thesis was submitted for the degree of Engineering Doctorate and awarded by Brunel University.Birds are a key environmental asset and this is recognised through comprehensive legislation and policy ensuring their protection and conservation. Many species are active at night and surveys are required to understand the implications of proposed developments such as towers and reduce possible conflicts with these structures. Night vision devices are commonly used in nocturnal surveys, either to scope an area for bird numbers and activity, or in remotely sensing an area to determine potential risk. This thesis explores some practical and theoretical approaches that can improve the accuracy, confidence and efficiency of nocturnal bird surveillance. As image intensifiers and thermal imagers have operational differences, each device has associated strengths and limitations. Empirical work established that image intensifiers are best used for species identification of birds against the ground or vegetation. Thermal imagers perform best in detection tasks and monitoring bird airspace usage. The typically used approach of viewing bird survey video from remote sensing in its entirety is a slow, inaccurate and inefficient approach. Accuracy can be significantly improved by viewing the survey video at half the playback speed. Motion detection efficiency and accuracy can be greatly improved through the use of adaptive background subtraction and cumulative image differencing. An experienced ornithologist uses bird flight style and wing oscillations to identify bird species. Changes in wing oscillations can be represented in a single inter-frame similarity matrix through area-based differencing. Bird species classification can then be automated using singular value decomposition to reduce the matrices to one-dimensional vectors for training a feed-forward neural network

The use of a shiphandling simulator to complement practical training at the Saudi Border Guard Naval Institute [SBGNI]

The dissertation introduces the use of a shiphandling simulator to complement the theoretical training of students at the Saudi Border Guard Naval Institute. A review of the requirements of the 1995 STCW Convention in regard to the use of simulators for training and assessment and the implementation of a quality standard system is undertaken. The training of students and also of experienced mariners is a task for which simulators have become an increasingly valuable tool. The use of simulators for training purposes is especially important for MET institutions in which the practical training of students on board training ships is decreasing and in those areas in which the use of real vessels for training shows a risk to the mariner, to the vessel, to property and to the environment. The background to the development and use of simulators is considered at length and the possibility of having simulators for both training and assessment of performance at the Institute is discussed. One of the conclusions is that trainees at the Institute can be trained in manoeuvring conditions that would take many years to encounter in real life, and that due to the modernisation of the fleet, the experienced mariner can benefit from this type of training when required to transfer to ships of different size, type, propulsion, manoeuvring systems and modem navigational equipment The dissertation concludes that a change is appropriate, if the SBGNI wants to modernise the programs and curriculum and that the actual theoretical training does not guarantee the ability to perform. This would be the role of simulation, to produce practical situations so that trainees could gain experience under controlled and repeatable conditions

The role of seas as a geographical barrier for migratory landbirds. An approach to the Bay of Biscay.

131 p.The East-Atlantic flyway represents one of the main bird migration routes worldwide, comprising the Bay of Biscayas an inherent geographical barrier. So far, the significance of the Bay of Biscay for migrants and its potentialimpact on migratory routes have not received much attention in research. The general aim of this thesis is to unravelthe role of the Bay of Biscay as a geographic barrier both at a small and large scale shaping the nocturnalmigration of landbirds moving along the East-Atlantic flyway. All observation tools available in the study regiondeemed suitable for nocturnal studies were employed: operational wind profiler and weather radars, thermalimaging and moonwatching. Previous knowledge from visual observations and bird ringing available in literaturewas also taken into account. Furthermore, in a pioneer approach, the study assessed the potential use ofwind profiler data in an ornithological context. An objective qualitative and quantitative approach validated bythermal imaging was established to extract migration parameters.Migration traffic rates, flight directions and altitudes obtained by the two types of radars and thermal imagingfor various sites along the bay are provided and discussed in a meteorological and ecological context. Verticalhistorical wind profiler and current thermal imaging data indicated pronounced broad-front migration in earlyspring vs. more eastward (i.e. sea-avoidance) migration in autumn. Moonwatching provided additional informationon bird composition and confirmed predominance of passerines. Finally, horizontal weather radar datarevealed a north-south gradient along the French coast in spring, with higher intensity in the south-easternstudy area close to the main migration axis of the East-Atlantic flyway.Aranzadi Zientzia Elkarte

WiseEye: next generation expandable and programmable camera trap platform for wildlife research

Funding: The work was supported by the RCUK Digital Economy programme to the dot.rural Digital Economy Hub; award reference: EP/G066051/1. The work of S. Newey and RJI was part funded by the Scottish Government's Rural and Environment Science and Analytical Services (RESAS). Details published as an Open Source Toolkit, PLOS Journals at: http://dx.doi.org/10.1371/journal.pone.0169758Peer reviewedPublisher PD