scholarly journals Infrasound as a Cue for Seabird Navigation

2021 ◽  
Vol 9 ◽  
Author(s):  
Samantha C. Patrick ◽  
Jelle D. Assink ◽  
Mathieu Basille ◽  
Susana Clusella-Trullas ◽  
Thomas A. Clay ◽  
...  
Keyword(s):  
Large Scale ◽  
Animal Species ◽  
Bird Species ◽  
Low Frequency ◽  
Temporal Consistency ◽  
Physiological Mechanisms ◽  
Breeding Sites ◽  
Spatio Temporal ◽  
Future Work

Seabirds are amongst the most mobile of all animal species and spend large amounts of their lives at sea. They cross vast areas of ocean that appear superficially featureless, and our understanding of the mechanisms that they use for navigation remains incomplete, especially in terms of available cues. In particular, several large-scale navigational tasks, such as homing across thousands of kilometers to breeding sites, are not fully explained by visual, olfactory or magnetic stimuli. Low-frequency inaudible sound, i.e., infrasound, is ubiquitous in the marine environment. The spatio-temporal consistency of some components of the infrasonic wavefield, and the sensitivity of certain bird species to infrasonic stimuli, suggests that infrasound may provide additional cues for seabirds to navigate, but this remains untested. Here, we propose a framework to explore the importance of infrasound for navigation. We present key concepts regarding the physics of infrasound and review the physiological mechanisms through which infrasound may be detected and used. Next, we propose three hypotheses detailing how seabirds could use information provided by different infrasound sources for navigation as an acoustic beacon, landmark, or gradient. Finally, we reflect on strengths and limitations of our proposed hypotheses, and discuss several directions for future work. In particular, we suggest that hypotheses may be best tested by combining conceptual models of navigation with empirical data on seabird movements and in-situ infrasound measurements.

scholarly journals Historical drought patterns over Canada and their teleconnections with large-scale climate signals

2018 ◽  
Vol 22 (6) ◽  
pp. 3105-3124 ◽  
Author(s):  
Zilefac Elvis Asong ◽  
Howard Simon Wheater ◽  
Barrie Bonsal ◽  
Saman Razavi ◽  
Sopan Kurkute
Keyword(s):  
Large Scale ◽  
Southern Oscillation ◽  
Low Frequency ◽  
Kendall Test ◽  
Wavelet Coherence ◽  
Climate Indices ◽  
Data Sets ◽  
Canadian Prairies ◽  
Agriculture Industry ◽  
Spatio Temporal

Abstract. Drought is a recurring extreme climate event and among the most costly natural disasters in the world. This is particularly true over Canada, where drought is both a frequent and damaging phenomenon with impacts on regional water resources, agriculture, industry, aquatic ecosystems, and health. However, nationwide drought assessments are currently lacking and impacted by limited ground-based observations. This study provides a comprehensive analysis of historical droughts over the whole of Canada, including the role of large-scale teleconnections. Drought events are characterized by the Standardized Precipitation Evapotranspiration Index (SPEI) over various temporal scales (1, 3, 6, and 12 consecutive months, 6 months from April to September, and 12 months from October to September) applied to different gridded monthly data sets for the period 1950–2013. The Mann–Kendall test, rotated empirical orthogonal function, continuous wavelet transform, and wavelet coherence analyses are used, respectively, to investigate the trend, spatio-temporal patterns, periodicity, and teleconnectivity of drought events. Results indicate that southern (northern) parts of the country experienced significant trends towards drier (wetter) conditions although substantial variability exists. Two spatially well-defined regions with different temporal evolution of droughts were identified – the Canadian Prairies and northern central Canada. The analyses also revealed the presence of a dominant periodicity of between 8 and 32 months in the Prairie region and between 8 and 40 months in the northern central region. These cycles of low-frequency variability are found to be associated principally with the Pacific–North American (PNA) and Multivariate El Niño/Southern Oscillation Index (MEI) relative to other considered large-scale climate indices. This study is the first of its kind to identify dominant periodicities in drought variability over the whole of Canada in terms of when the drought events occur, their duration, and how often they occur.

scholarly journals In situ predator conditioning of naive prey prior to reintroduction

2019 ◽  
Vol 374 (1781) ◽  
pp. 20180058 ◽  
Author(s):  
Daniel T. Blumstein ◽  
Mike Letnic ◽  
Katherine E. Moseby
Keyword(s):  
Small Groups ◽  
Large Scale ◽  
Management Tool ◽  
Behavioural Ecology ◽  
Ecological Community ◽  
Theme Issue ◽  
Selection For ◽  
Future Work ◽  
Dynamics Of Populations

Many translocations and introductions to recover threatened populations fail because predators kill prey soon after release; a problem exacerbated for predator-naive prey. While pre-release training has been shown to work in some situations, it is time consuming and relies on using inferred predator cues and treating small groups. We review a relatively new and very promising management tool: in situ , pre-release predator conditioning. Here, the goal is to allow prey in large enclosures to live with low densities of predators to accelerate selection for antipredator traits (in an evolutionary sense) or provide prey essential experience with predators that they will later encounter. We review the published results of a large-scale, controlled experiment where we have permitted burrowing bettongs ( Bettongia lesueur ) and greater bilblies ( Macrotis lagotis ) to live with low densities of feral cats ( Felis catus ), a species implicated in their widespread decline and localized extinction. We found that both species could persist with cats, suggesting that future work should define coexistence thresholds—which will require knowledge of prey behaviour as well as the structure of the ecological community. Compared to control populations, predator-naive prey exposed to cats has a suite of morphological and behavioural responses that seemingly have increased their antipredator abilities. Results suggest that predator-conditioned bilbies survive better when released into a large enclosure with an established cat population; future work will determine whether this increased survival extends to the wild. This article is part of the theme issue ‘Linking behaviour to dynamics of populations and communities: application of novel approaches in behavioural ecology to conservation’.

Periodically arranged co-flowing jets

1994 ◽  
Vol 263 ◽  
pp. 63-92 ◽  
Author(s):  
E. Villermaux ◽  
E. J. Hopfinger
Keyword(s):  
Large Scale ◽  
Travelling Waves ◽  
Spatial Coherence ◽  
Low Frequency ◽  
Periodic Pattern ◽  
Low Frequency Oscillation ◽  
Recirculating Flow ◽  
Point Correlation ◽  
Spatio Temporal ◽  
New Formulation

The problem of a periodic planar arrangement of a large number of co-flowing, interacting jets is investigated. It is shown that this interaction gives rise to strong nearfield oscillations of large-scale spatial coherence and to far-field inhomogeneities. In the experiments performed, the jets were produced behind a flat plate perforated by holes arranged in a square or triangular periodic pattern and placed perpendicular to a uniform flow. At moderate Reynolds numbers, the interaction results in a remarkable low-frequency oscillation of the merging distance of the jets downstream of the plate. A detailed description of the recirculating flow in the cavities between the jets emphasizes the role of the backflow in the cavities on the oscillatory behaviour. This description is supported by measurements of the local fluctuating velocity and pressure, two-point correlation measurements and quantitative flow visualizations. These experimental observations suggest a new formulation for the instability dynamics of such unstable recirculating flows. This formulation, based on the nonlinear delayed saturation of the jet's shear layer instability (NLDS model) predicts successfully the dependence of the oscillation of the merging distance on the jet Reynolds number and on the local geometrical features of the confinement of the jets. Furthermore, it is shown that the diffusion of mass coming from one jet, seeded with an inert dye, gives rise to an exponential diffusion front over a distance corresponding to a few mesh sizes indicating a strong local coupling of the jets. At the scale of the whole jet assembly, the oscillations are organized as large-scale travelling waves, propagating from the boundaries of the domain to its centre. This symmetry-breaking property is discussed and supplemented by a spatio-temporal simulation of an array of coupled oscillators.

scholarly journals Migrating Curlews on Schedule: Departure and Arrival Patterns of a Long-Distance Migrant Depend on Time Rather than on Wind Conditions

2020 ◽  
Author(s):  
Philipp Schwemmer ◽  
Moritz Mercker ◽  
Klaus Heinrich Vanselow ◽  
Pierrick Bocher ◽  
Stefan Garthe
Keyword(s):  
Wadden Sea ◽  
Bird Species ◽  
Weather Conditions ◽  
Internal Clock ◽  
Migratory Bird ◽  
Long Distance ◽  
Breeding Sites ◽  
Timing Of Migration ◽  
Spatio Temporal ◽  
Selection Operator

Abstract Background: Choosing the appropriate time to depart for spring migration is crucial to achieving a successful subsequent breeding season among migratory bird species. We expected Eurasian Curlews (Numenius arquata) to start their migration during favourable weather conditions and to adjust their flight heights to prevailing wind conditions.Methods: We equipped 23 curlews with Global Positioning System data loggers to record the spatio-temporal patterns of their departure from and arrival at their wintering site in the Wadden Sea, as well as the first part of their migration. We obtained data for 42 curlew migrations over a period of 6 years. Departure and arrival dates were related to 73 meteorological and bird-related predictors using the least absolute shrinkage and selection operator (LASSO) to identify drivers of departure and arrival decisions.Results: Curlews migrated almost exclusively to the western part of Russia for breeding. They left the Wadden Sea mainly during the evening hours from mid- to late April and returned between the end of June and mid-July. There was no difference in departure times between the sexes, but males tended to return from their breeding sites later than females. Flight speeds of the birds increased significantly with increasing tailwind component, suggesting that they timed their migration according to favourable wind conditions. However, curlews left the Wadden Sea during various wind and weather conditions, with significant numbers leaving during headwind conditions, in contrast to the apparent wind-driven start of migration. Curlews migrated at very low altitudes during tailwind conditions, but flew significantly higher during headwind conditions, at altitudes of up to several kilometres. Departure dates varied by <4 days in individual curlews that were tagged over consecutive years. Conclusions: Our results suggest that the start of migration in a long-distance migrant mainly depends on the date and is independent of weather conditions. Given the high repeatability of the departure day among subsequent years, this clearly suggests the existence of an internal clock prompting the start of migration. Further insights into the timing of migration in immatures and closely related birds might help us to understand the genetic mechanisms triggering temporal migration patterns.

scholarly journals Large-scale chromosomal restructuring is induced by the transposable element tam3 at the nivea locus of antirrhinum majus.

Genetics ◽  
1988 ◽  
Vol 119 (1) ◽  
pp. 171-184
Author(s):  
C Martin ◽  
S Mackay ◽  
R Carpenter
Keyword(s):  
Transposable Element ◽  
Large Scale ◽  
Molecular Level ◽  
Chromosomal Rearrangements ◽  
Low Frequency ◽  
Antirrhinum Majus ◽  
Inverted Duplication ◽  
Imprecise Excision ◽  
Flanking Sequences

Abstract The transposable element, Tam3, gives rise to large-scale (greater than 1 kb) chromosomal rearrangements at a low frequency, when it is inserted at the nivea locus of Antirrhinum majus. Although some deletions may result from imprecise excision of Tam3, rearrangements involving deletion, dispersion and inverted duplication of flanking sequences, where Tam3 remains in situ, have also been identified. These rearrangements have been mapped at the molecular level, and the behavior of Tam3 following rearrangement has been observed. It is clear that Tam3 has enormous potential to restructure chromosomes through successive rounds of large-scale rearrangements. The mechanisms by which such rearrangements might arise are discussed.

scholarly journals Ice calving and deformation from Antarctic Ice margins using RISAT-1 circular polarization SAR data

2014 ◽  
Vol XL-8 ◽  
pp. 525-529 ◽  
Author(s):  
P. Jayaprasad ◽  
D. R. Rajak ◽  
R. K. Singh ◽  
S. R. Oza ◽  
R. Sharma ◽  
...  
Keyword(s):  
Large Scale ◽  
Research Station ◽  
Ice Shelf ◽  
Summer Period ◽  
Glacier Tongue ◽  
Amery Ice Shelf ◽  
Antarctic Research ◽  
Sar Data ◽  
Spatio Temporal

In the present study, quantification of spatial and temporal changes has been carried out between Indian Antarctic Research station Bharati and Amery ice shelf by monitoring the ice margins using RISAT-1 Synthetic Aperture Radar (SAR) data. Spatio-temporal change detection was carried out by comparing the feature's geographic locations from geometrically rectified SAR data from RISAT-1 (Dec. 2013), Radarsat-2 (Feb. 2013), and Antarctic Mapping Mission products of Radarsat-1 (1997 & 2000). We report large scale disintegrations at two prominent glacier tongues namely Polar Record Glacier (PRG) and Polar Times Glacier(PTG). The results are verified against in-situ ground observations made during Summer period of 33rd ISEA (Dec. 2013&ndash;Feb. 2014) and MODIS images from NSIDC archive. Polar Record Glacier Tongue (PRGT) was drastically deformed by 135.8 km2 and Polar Times Glacier Tongue (PTGT) was partly calved by ~195.6 km2 and moved away by ~23 km especially between February and December 2013.

scholarly journals Dual polarization measurements of MWA beampatterns at 137 MHz

2021 ◽  
Vol 502 (2) ◽  
pp. 1990-2004
Author(s):  
A Chokshi ◽  
J L B Line ◽  
N Barry ◽  
D Ung ◽  
D Kenney ◽  
...  
Keyword(s):  
Large Scale ◽  
Dynamic Range ◽  
Low Frequency ◽  
Beam Model ◽  
Instrumental Effects ◽  
Phased Array Antenna ◽  
Environmental Perturbations ◽  
Murchison Widefield Array ◽  
The Many

ABSTRACT The wide adoption of low-frequency radio interferometers as a tool for deeper and higher resolution astronomical observations has revolutionized radio astronomy. Despite their construction from static, relatively simple dipoles, the sheer number of distinct elements introduces new, complicated instrumental effects. Their necessary remote locations exacerbate failure rates, while electronic interactions between the many adjacent receiving elements can lead to non-trivial instrumental effects. The Murchison Widefield Array (MWA) employs phased array antenna elements (tiles), which improve collecting area at the expense of complex beam shapes. Advanced electromagnetic simulations have produced the fully embedded element (FEE) simulated beam model which has been highly successful in describing the ideal beam response of MWA antennas. This work focuses on the relatively unexplored aspect of various in-situ, environmental perturbations to beam models and represents the first large-scale, in-situ, all-sky measurement of MWA beam shapes at multiple polarizations and pointings. Our satellite based beam measurement approach enables all-sky beam response measurements with a dynamic range of ∼50 dB, at 137 MHz.

scholarly journals Adaptive In-Situ Visualization Considering Spatio-temporal changes of Large-scale Numerical Simulation Results

2019 ◽  
Vol 2019 (0) ◽  
pp. IS-52
Author(s):  
Yoshiaki YAMAOKA ◽  
Kengo HAYASHI ◽  
Naohisa SAKAMOTO ◽  
Jorji NONAKA ◽  
Tsukasa YOSHINAGA ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Large Scale ◽  
Temporal Changes ◽  
In Situ Visualization ◽  
Simulation Results ◽  
Spatio Temporal

scholarly journals The diversity of maternal-age effects upon pre-adult survival across animal species

2020 ◽  
Vol 287 (1932) ◽  
pp. 20200972
Author(s):  
Edward Ivimey-Cook ◽  
Jacob Moorad
Keyword(s):  
Maternal Age ◽  
Animal Species ◽  
Detrimental Effect ◽  
Bird Species ◽  
Age Effects ◽  
Adult Survival ◽  
Offspring Performance ◽  
Older Mothers ◽  
Proximate Causes ◽  
Future Work

Maternal senescence is the detrimental effect of increased maternal age on offspring performance. Despite much recent interest given to describing this phenomenon, its distribution across animal species is poorly understood. A review of the published literature finds that maternal age affects pre-adult survival in 252 of 272 populations (93%) representing 97 animal species. Age effects tended to be deleterious in invertebrates and mammals, including humans, confirming the presence of senescence. However, bird species were a conspicuous exception, as pre-adult survival tended to increase with maternal age in surveyed populations. In all groups, maternal-age effects became more negative in older mothers. Invertebrates senesced faster than vertebrates, and humans aged faster than non-human mammals. Within invertebrates, lepidopterans demonstrated the most extreme rates of maternal-effect senescence. Among the surveyed studies, phylogeny, life history and environment (e.g. laboratory versus wild populations) were tightly associated; this made it difficult to make confident inferences regarding the causes of diversity for the phenomenon. However, we provide some testable suggestions, and we observe that some differences appear to be consistent with predictions from evolutionary theory. We discuss how future work may help clarify ultimate and proximate causes for this diversity.

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