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Model‐based acoustic localisation estimates the locations of underwater objects by comparing sensor measurements with model predictions. To obtain high quality predictions, propagation models need to be run for a large set of environmental parameters. However, real‐time Model‐based acoustic localisation estimations using onboard computational resources are often limited. To address this, the authors propose a Quantum annealing (QA) algorithm for enhancing underwater acoustic localisation. A restricted Boltzmann machine (RBM) is trained to predict the probability distribution of underwater targets. Advantage of this approach is that part of the computation is moved to offline‐training. Moreover, the probability distribution can potentially be sampled efficiently using a quantum annealer possibly enabling real‐time accurate target estimations being made onboard.The RBM is applied to a simplified multi‐sensor horizontal localisation problem where a constant and linear acoustic propagation is assumed. Using simulated annealing the authors show that the RBM is able to learn probability distributions that resemble target locations. Preliminary results show that training and sampling the RBM can be done using QA hardware by D‐Wave Systems.However, there remains room for improvement especially in ranging predictions. Further research into possible benefits of QA RBMs is needed to provide theoretical and practical results of a speed‐up. [ABSTRACT FROM AUTHOR]

Artificial light at night (ALAN) is considered as a major threat to biodiversity, especially to nocturnal species, as it reduces availability, quality and functionality of habitats. However, its effects on the way species use landscape elements such as rivers are still largely understudied, especially the effect of crossing infrastructure lighting on bridges. These elements are nevertheless key commuting and foraging habitats in heavily urbanised landscapes for several taxa such as bats that are particularly affected by ALAN. We studied the effects of the illumination of facades and undersides of bridges on the relative abundance of pipistrelle bats, on their 3D distribution and their behavioural response (i.e. flight speed) close to bridges. We set‐up an innovative approach based on a microphone‐array to reconstruct positions and flight trajectories in 3D. We studied the effect of lighting on bats in the close proximity of six similar bridges, mostly differentiated by the presence or absence of lighting (3 lit and 3 unlit). All bridges cross the same waterway, within a uniformly and highly urbanized agglomeration (Toulouse, France). We found that bat activity was 1.7 times lower in lit sites. Bats tended to keep a larger distance, and to fly faster close to illuminated bridges. These results suggest that bridge lighting strongly reduces habitat availability and likely connectivity for bats. In that case, results call for switching off the illumination of such bridges crossing riverine ecosystems to preserve their functionality as habitats and corridors for bats. [ABSTRACT FROM AUTHOR]

Acoustic localisation technology has been widely tested and applied for passive acoustic monitoring and ecological research, however, hardware costs of commercially available devices limit scalability. Furthermore, few studies have explored its use with low-density arrays. We present a low-cost, custom-designed hardware and software system termed 'CARACAL' that is able to extract and localise weak acoustic signals. The key to this is the use of four microphones on each logger, allowing for phase-based measurements and the ability to enhance signal-to-noise ratio through beamforming. As a proof of concept, we test the functionality of the CARACAL system by conducting a gunshot localisation experiment and demonstrate animal call detection and localisation from a lion predation event. Results show the system could locate gunshots with an average accuracy of 33.2 ± 15.3 m within an array of 7 stations 500 m apart. When applied to animal call positioning, we show long range (> 1 km) localisation of three different species' calls, Cape buffalo, chacma baboon and spotted hyaena. With a cost of approximately £150 per unit, the CARACAL system provides a cost-effective solution for acoustic localisation over large areas. The system is open source and can be customised to suit a variety of wildlife research applications. [ABSTRACT FROM AUTHOR]