Anthropogenic noise is associated with changes in acoustic but not visual signals in red-winged blackbirds

Some birds in noisy areas produce songs with higher frequency and/or amplitude and altered timing compared to individuals in quiet areas. These changes may function to increase the efficacy of acoustic signals by reducing masking by noise. We collected audio recordings of red-winged blackbirds and measured noise levels. We found that males in noisier places produced songs with fewer syllables and slower repeat rate of elements in some components (rattles). Birds may also improve the efficacy of communication in noise by increasing usage of other signaling modalities. Red-winged blackbirds also perform a visual display in different intensities while singing. We also tested whether this species performs the visual display in different intensities according to current noise levels, and predicted that if the efficacy of songs is impaired in noisy places, males would compensate by performing a more intense visual display. For this, we also collected visual recordings from the same males from which we obtained acoustic recordings. We found no association between acoustic noise and the intensity of the visual display; thus, our results do not support the idea that males are using the visual display as a backup signal to communicate under acoustic noise. We discuss some possible explanations of this negative finding and for the observed noise-related changes in song length and rattle rate in the context of communication under noise

Seasonal variability in habitat structure may have shaped acoustic signals and repertoires in the black-capped and boreal chickadees

Many songbird species have evolved multiple vocalizations, or repertoires, that function to communicate various biological signals. More diverse repertoires may have evolved in response to the effects of seasonal variation in habitat structure on signal transmission. Such changes in habitat necessarily occur for migrating species, but they also occur for resident species that occupy deciduous forests. The black-capped chickadee (P. atricapillus), possesses a chick-a-dee call and a fee-bee song, but the closely related boreal chickadee (P. borealis) lacks a song. Consistent with the habitat variability hypothesis, the black-capped chickadee possesses a larger repertoire and primarily occupies deciduous forests, whereas the songless boreal chickadee occurs more often in coniferous forests. We explored the ecological basis of this hypothesis by recording audio playbacks of two species in two habitat types during two seasons. Specifically, we played both songs and calls of the black-capped chickadee and calls of the boreal chickadee in deciduous and coniferous habitats, prior to and after leaf-out. We measured attenuation and degradation in the re-recorded vocalizations. For black-capped chickadees, the song was less degraded than the call in post-leaf, deciduous forests. The boreal chickadee call attenuated more quickly in all treatments, but maintained its acoustic structure better than both black-capped chickadee vocalizations in coniferous forests. Our results support the hypothesis that variable habitats provided a seasonal transmission benefit for both song and call in the black-capped chickadee, but that the transmission benefit of song is lost in the less variant coniferous forests, which may underlie the absence of a song in the boreal chickadee

A geospatial multi-scale level analysis of the distribution of animal-vehicle collisions on Polish highways and national roads

This article has the aim to investigate the spatial distribution of animal-vehicle collisions (AVCs) in Poland on national roads and motorways. Besides identifying hot spot locations of animal mortality within the country, it also researches on regional scale the relationship between levels of traffic volume or traffic speed and the amount of AVCs. The analysis involves data collected by the Polish General Directorate for National Roads and Motorways with 2014 until 2017 as time range. The geospatial analyses are carried out with QGIS. The Małopolska Province has the highest concentration of AVCs in Poland. Results of the analysis on regional level show that traffic speed and traffic volume are both not strongly correlating to the total animal mortality, meaning that higher levels of the parameters do not lead to higher amounts of AVCs. Accidents occur most frequently on road sections with a traffic volume of an average number of 10,000 to 15,000 vehicles per day. The severe accidents with large sized animals, the Big-Four, are occurring most often at road sections with speed limits between 70 and 90 km/h. This work will be continued, which will investigate the influence of the landscape adjacent to the road on a local scale

No frequency shift in the “D” notes of Carolina chickadee calls in response to traffic noise

Loud, low-frequency traffic noise can mask songbird vocalizations, and populations of some urban songbird species have shifted the frequency of their vocalizations upward in response. However, the spectral structure of certain vocalization elements may make them resistant to masking, suggesting that species that use these notes could be more successful in areas with high levels of traffic noise. To test this idea, we recorded Carolina chickadees (Poecile carolinensis), whose calls feature “D” notes with an overtone spectral structure, along a traffic noise gradient in Durham and Orange Counties, North Carolina, USA. Frequency parameters of “D” notes did not change with noise level suggesting the possibility that these notes can be communicated effectively in noise, but further investigation is needed to test this hypothesis directly. In addition, we performed a playback experiment demonstrating how the use of spectrograms to measure note frequencies is unreliable, especially when recordings are made in noisy areas. We used an alternative method based on the predictable frequency structure of “D” notes. Our experiment is one of few that address the effects of urban noise on calls produced by both sexes as opposed to song produced only by males during the breeding season. Understanding how vocalizationswith different spectral structures may be affected differentially by traffic noise will increase our ability to predict how the expansion of noisy areas may impact songbird community composition in the future

Low cost (audio) recording (LCR) for advancing soundscape ecology towards the conservation of sonic complexity and biodiversity in natural and urban landscapes

Low cost (audio) recorders (LCRs) represent a new opportunity to investigate the sonic complexity of both natural and urban ecosystems. LCRs are inexpensive sampling audio recorders which have the external shape of a universal serial bus (USB) flash drive, and are composed of a microphone, an analog-to-digital converter, central processing unit with permanent internal non-volatile memory, rechargeable battery, and a USB connection. The reduced dimen­sions allow the device to be deployed inconspicuously within any environment, in any config­uration and for an extended time period. This investigation tested a specific type of LCR (UR-09) with a spectral range of 8 kHz -sufficient to cover the acoustic range of most western Palearctic songbirds. The reliability of the UR-09, compared with other commercial recorders (Zoom H4 and Song Meter SM1) and based on the quality of recordings quantified by the Acoustic Complexity Index (ACI), was tested and confirmed. An example of the application of LCRs is presented in an evaluation of the audio patterns occurring during dawn and dusk choruses within a forested ecosystem. Results of this investigation are encouraging and a new generation of LCR devices is currently being designed with real-time acoustic data processing capabilities, timer programmability, a larger frequency range and wireless communication compatibility. LCRs are revealed to be ideal instruments to conduct surveys in fragile or protected areas and also in urban environments. Moreover, due to their low cost, they can be used to encourage research in soundscape ecology, especially within developing countries, where large areas can be monitored by professionals or incorporating citizen science models of data collection. Keywords Soundscape ecology . Low cost (audio) recorders . Acoustic complexity index . Acoustic monitoring . Citizen science . Urban ecosystem

2D matrix engineering for homogeneous quantum dot coupling in photovoltaic solids

Colloidal quantum dots (CQDs) are promising photovoltaic (PV) materials because of their widely tunable absorption spectrum controlled by nanocrystal size1,2. Their bandgap tunability allows not only the optimization of single-junction cells, but also the fabrication of multijunction cells that complement perovskites and silicon 3 . Advances in surface passivation2,4-7, combined with advances in device structures 8 , have contributed to certified power conversion efficiencies (PCEs) that rose to 11% in 2016 9 . Further gains in performance are available if the thickness of the devices can be increased to maximize the light harvesting at a high fill factor (FF). However, at present the active layer thickness is limited to ~300 nm by the concomitant photocarrier diffusion length. To date, CQD devices thicker than this typically exhibit decreases in short-circuit current (JSC) and open-circuit voltage (VOC), as seen in previous reports3,9-11. Here, we report a matrix engineering strategy for CQD solids that significantly enhances the photocarrier diffusion length. We find that a hybrid inorganic-amine coordinating complex enables us to generate a high-quality two-dimensionally (2D) confined inorganic matrix that programmes internanoparticle spacing at the atomic scale. This strategy enables the reduction of structural and energetic disorder in the solid and concurrent improvements in the CQD packing density and uniformity. Consequently, planar devices with a nearly doubled active layer thicknesses (~600 nm) and record values of JSC (32 mA cm-2) are fabricated. The VOC improved as the current was increased. We demonstrate CQD solar cells with a certified record efficiency of 12%.This publication is based in part on work supported by the Natural Sciences and Engineering Research Council of Canada, by the Ontario Research Fund Research Excellence Program and by Award OSR-2017-CPF-3321-03 made by King Abdullah University of Science and Technology (KAUST). Some of the GIWAXS/GISAXS measurements were performed at the Cornell High Energy Synchrotron Source (CHESS), supported by the NSF Award DMR-1332208. This work also made use of the South Carolina SAXS Collaborative using a SAXSLab Ganesha for the GISAXS/GIWAXS measurements, supported by the NSF Major Research Instrumentation program (award no. DMR-1428620). We thank U. Jeng for the GIWAXS tested at the National Synchrotron Radiation Research Center, Taiwan, China. We thank L. Goncharova for assistance with RBS measurements. We thank D. Kopilovic, E. Palmiano, L. Levina and R. Wolowiec for the technical support