scholarly journals Evidence for a pervasive ‘idling-mode’ activity template in flying and pedestrian insects

2015 ◽  
Vol 2 (5) ◽  
pp. 150085 ◽  
Author(s):  
Andrew M. Reynolds ◽  
Hayley B. C. Jones ◽  
Jane K. Hill ◽  
Aislinn J. Pearson ◽  
Kenneth Wilson ◽  
...  
Keyword(s):  
Activity Patterns ◽  
Movement Ecology ◽  
Movement Patterns ◽  
Environmental Cues ◽  
Natural Environments ◽  
Scale Invariant ◽  
Scale Free ◽  
Flight Mills ◽  
Innate Behaviour ◽  
Multiple Species

Understanding the complex movement patterns of animals in natural environments is a key objective of ‘movement ecology’. Complexity results from behavioural responses to external stimuli but can also arise spontaneously in their absence. Drawing on theoretical arguments about decision-making circuitry, we predict that the spontaneous patterns will be scale-free and universal, being independent of taxon and mode of locomotion. To test this hypothesis, we examined the activity patterns of the European honeybee, and multiple species of noctuid moth, tethered to flight mills and exposed to minimal external cues. We also reanalysed pre-existing data for Drosophila flies walking in featureless environments. Across these species, we found evidence of common scale-invariant properties in their movement patterns; pause and movement durations were typically power law distributed over a range of scales and characterized by exponents close to 3/2. Our analyses are suggestive of the presence of a pervasive scale-invariant template for locomotion which, when acted on by environmental cues, produces the movements with characteristic scales observed in nature. Our results indicate that scale-finite complexity as embodied, for instance, in correlated random walk models, may be the result of environmental cues overriding innate behaviour, and that scale-free movements may be intrinsic and not limited to ‘blind’ foragers as previously thought.

Movement patterns of feral predators in an arid environment – implications for control through poison baiting

2009 ◽  
Vol 36 (5) ◽  
pp. 422 ◽  
Author(s):  
K. E. Moseby ◽  
J. Stott ◽  
H. Crisp
Keyword(s):  
Home Range ◽  
Sand Dunes ◽  
Activity Patterns ◽  
Movement Patterns ◽  
Home Range Size ◽  
Range Size ◽  
Home Ranges ◽  
Feral Cats ◽  
Poison Baiting ◽  
Specific Variation

Control of introduced predators is critical to both protection and successful reintroduction of threatened prey species. Efficiency of control is improved if it takes into account habitat use, home range and the activity patterns of the predator. These characteristics were studied in feral cats (Felis catus) and red foxes (Vulpes vulpes) in arid South Australia, and results are used to suggest improvements in control methods. In addition, mortality and movement patterns of cats before and after a poison-baiting event were compared. Thirteen cats and four foxes were successfully fitted with GPS data-logger radio-collars and tracked 4-hourly for several months. High intra-specific variation in cat home-range size was recorded, with 95% minimum convex polygon (MCP) home ranges varying from 0.5 km2 to 132 km2. Cat home-range size was not significantly different from that of foxes, nor was there a significant difference related to sex or age. Cats preferred habitat types that support thicker vegetation cover, including creeklines and sand dunes, whereas foxes preferred sand dunes. Cats used temporary focal points (areas used intensively over short time periods and then vacated) for periods of up to 2 weeks and continually moved throughout their home range. Aerial baiting at a density of 10 baits per km2 was ineffective for cats because similar high mortality rates were recorded for cats in both baited and unbaited areas. Mortality was highest in young male cats. Long-range movements of up to 45 km in 2 days were recorded in male feral cats and movement into the baited zone occurred within 2 days of baiting. Movement patterns of radio-collared animals and inferred bait detection distances were used to suggest optimum baiting densities of ~30 baits per km2 for feral cats and 5 per km2 for foxes. Feral cats exhibited much higher intra-specific variation in activity patterns and home-range size than did foxes, rendering them a potentially difficult species to control by a single method. Control of cats and foxes in arid Australia should target habitats with thick vegetation cover and aerial baiting should ideally occur over areas of several thousand square kilometres because of large home ranges and long-range movements increasing the chance of fast reinvasion. The use of temporary focal points suggested that it may take several days or even weeks for a cat to encounter a fixed trap site within their home range, whereas foxes should encounter them more quickly as they move further each day although they have a similar home-range size. Because of high intra-specific variability in activity patterns and home-range size, control of feral cats in inland Australia may be best achieved through a combination of control techniques.

scholarly journals Scale-free, programmable design of morphable chain loops of kilobots and colloidal motors

2020 ◽  
Vol 117 (16) ◽  
pp. 8700-8710
Author(s):  
Mayank Agrawal ◽  
Sharon C. Glotzer
Keyword(s):  
Brownian Dynamics ◽  
Colloidal Particles ◽  
Autonomous Robots ◽  
Design Strategy ◽  
Dynamics Simulation ◽  
Design Parameters ◽  
Brownian Dynamics Simulation ◽  
Scale Invariant ◽  
Scale Free ◽  
Mechanical Constraints

Micron-scale robots require systems that can morph into arbitrary target configurations controlled by external agents such as heat, light, electricity, and chemical environment. Achieving this behavior using conventional approaches is challenging because the available materials at these scales are not programmable like their macroscopic counterparts. To overcome this challenge, we propose a design strategy to make a robotic machine that is both programmable and compatible with colloidal-scale physics. Our strategy uses motors in the form of active colloidal particles that constantly propel forward. We sequence these motors end-to-end in a closed chain forming a two-dimensional loop that folds under its mechanical constraints. We encode the target loop shape and its motion by regulating six design parameters, each scale-invariant and achievable at the colloidal scale. We demonstrate the plausibility of our design strategy using centimeter-scale robots called kilobots. We use Brownian dynamics simulation to explore the large design space beyond that possible with kilobots, and present an analytical theory to aid the design process. Multiple loops can also be fused together to achieve several complex shapes and robotic behaviors, demonstrated by folding a letter shape “M,” a dynamic gripper, and a dynamic pacman. The material-agnostic, scale-free, and programmable nature of our design enables building a variety of reconfigurable and autonomous robots at both colloidal scales and macroscales.

Erosion, deposition and size distributions of sand

1988 ◽  
Vol 417 (1853) ◽  
pp. 335-352 ◽  
Keyword(s):  
Depositional Environments ◽  
Natural Environments ◽  
Size Distributions ◽  
Scale Invariant ◽  
Erosion And Deposition ◽  
Triangular Domain ◽  
Hand Part ◽  
Mass Size ◽  
Two Parameters ◽  
The Right

A mathematical–physical model for erosion and deposition of sand is formulated and related to the logarithmic hyperbolic distributional form of mass–size distributions. The location-scale invariant parameters χ and ξ of the hyperbolic distribution express, respectively, the skewness and the kurtosis of that distribution, and the triangular domain of variation of these two parameters is referred to as the hyperbolic shape triangle. The erosion–deposition model implies that erosion will tend to move the ( χ , ξ)-position of a given sediment to the right-hand part of the shape triangle and that deposition will move the ( χ , ξ)-position towards the left part of the triangle, along specified curves. This is confirmed by sediments from a variety of natural environments. An empirically determined curve bisecting the shape triangle is found to separate the samples from predominantly depositional environments as compared with the samples from predominantly erosional environments. The hyperbolic shape triangle is also found to discriminate well between samples of different but closely related origins.

Short-term movement patterns and diet of small dasyurid marsupials in semiarid Australia

2012 ◽  
Vol 34 (1) ◽  
pp. 49 ◽  
Author(s):  
Lisa Warnecke ◽  
Gerhard Körtner ◽  
Chris J. Burwell ◽  
James M. Turner ◽  
Fritz Geiser
Keyword(s):  
Spatial Ecology ◽  
Arid Zone ◽  
Activity Patterns ◽  
Movement Patterns ◽  
Small Scale ◽  
Radio Tracking ◽  
Short Term ◽  
Resting Sites ◽  
Sminthopsis Crassicaudata ◽  
Radio Transmitters

Since little information is available on the spatial ecology of small arid-zone marsupials, we used radio-tracking to investigate the small-scale activity patterns of three dasyurid species in semiarid Australia. Sminthopsis crassicaudata, Planigale gilesi and S. macroura were equipped with miniature radio-transmitters to monitor choice of resting sites and daily movements. Resting sites were located within an area of 1.27 ± 0.36 ha, 0.12 ± 0.02 ha and 3.60 ± 0.95 ha, respectively and individuals returned to previously used resting sites regularly. We also analysed scat samples of S. crassicaudata and P. gilesi, and identified Araneae, Hymenoptera and Orthoptera as the major prey taxa for both species. Our study presents the first radio-tracking-based information on movements for these species in semiarid habitat, which indicates that, over a period of several weeks, resting sites are situated within small and defined areas.

SELF-ORGANIZED CRITICALITY IN AN EARTHQUAKE MODEL BASED ON ASSORTATIVE SCALE-FREE NETWORKS

2011 ◽  
Vol 22 (05) ◽  
pp. 483-493 ◽  
Author(s):  
MIN LIN ◽  
GANG WANG
Keyword(s):  
Stress Evolution ◽  
Scale Invariant ◽  
Avalanche Size ◽  
Scale Free ◽  
Self Organized ◽  
Dynamical Behaviors ◽  
Period Distribution ◽  
Scale Free Networks ◽  
Earthquake Model ◽  
Self Organized Criticality

A modified Olami–Feder–Christensen (OFC) earthquake model on scale-free networks with assortative mixing is introduced. In this model, the distributions of avalanche sizes and areas display power-law behaviors. It is found that the period distribution of avalanches displays a scale-invariant law with the increment of range parameter d. More importantly, different assortative topologies lead to different dynamical behaviors, such as the distribution of avalanche size, the stress evolution process, and period distribution.

scholarly journals Pelagic seabird flight patterns are consistent with a reliance on olfactory maps for oceanic navigation

2015 ◽  
Vol 282 (1811) ◽  
pp. 20150468 ◽  
Author(s):  
Andrew M. Reynolds ◽  
Jacopo G. Cecere ◽  
Vitor H. Paiva ◽  
Jaime A. Ramos ◽  
Stefano Focardi
Keyword(s):  
Atlantic Ocean ◽  
North Atlantic Ocean ◽  
Movement Ecology ◽  
Wild Birds ◽  
Olfactory Cues ◽  
Invasive Approach ◽  
Scale Free ◽  
Non Invasive ◽  
Calonectris Borealis ◽  
Central Atlantic

Homing studies have provided tantalizing evidence that the remarkable ability of shearwaters ( Procellariiformes ) to pinpoint their breeding colony after crossing vast expanses of featureless open ocean can be attributed to their assembling cognitive maps of wind-borne odours but crucially, it has not been tested whether olfactory cues are actually used as a system for navigation. Obtaining statistically important samples of wild birds for use in experimental approaches is, however, impossible because of invasive sensory manipulation. Using an innovative non-invasive approach, we provide strong evidence that shearwaters rely on olfactory cues for oceanic navigation. We tested for compliance with olfactory-cued navigation in the flight patterns of 210 shearwaters of three species (Cory's shearwaters, Calonectris borealis , North Atlantic Ocean, Scopoli's shearwaters, C. diomedea Mediterranean Sea, and Cape Verde shearwaters, C. edwardsii , Central Atlantic Ocean) tagged with high-resolution GPS loggers during both incubation and chick rearing. We found that most (69%) birds displayed exponentially truncated scale-free (Lévy-flight like) displacements, which we show are consistent with olfactory-cued navigation in the presence of atmospheric turbulence. Our analysis provides the strongest evidence yet for cognitive odour map navigation in wild birds. Thus, we may reconcile two highly disputed questions in movement ecology, by mechanistically connecting Lévy displacements and olfactory navigation. Our approach can be applied to any species which can be tracked at sufficient spatial resolution, using a GPS logger.

scholarly journals Movement ecology of jaguars and predator-prey interactions.

2021 ◽  
Author(s):  
Carlos Cruz González ◽  
Daniela Medellin ◽  
Vicente Urios ◽  
Heliot Zarza ◽  
Gerardo Ceballos
Keyword(s):  
Average Distance ◽  
Activity Patterns ◽  
Movement Ecology ◽  
Suitable Habitat ◽  
Mean Values ◽  
Predator Prey ◽  
Gps Collars ◽  
Co Detection ◽  
Males And Females ◽  
Spatio Temporal

Jaguars (Panthera onca) are the largest felids in America, mainly threatened by habitat and prey density loss and hunting. Jaguars are mainly nocturnal predators that need large portions of suitable habitat with abundant prey populations. The aim of this work was to assess both jaguar and prey activity patterns, their relations and to understand if the presence/absence of prey and their activity patterns might determine the movements of jaguars in a spatio-temporal frame. We used data from camera trapping records of 125 jaguar events of presence from 9,360 camera trap days effort and data from five jaguars with GPS collars, to analyze: 1) Activity patterns; 2) Speed movement; 3) Traveled distances and 4) Co-occurrence for jaguars and preys. Differences between sexes and between seasons were also evaluated. A total of 12,566 segments of movement were recorded. Two activity peaks were identified between 07:00-08:00 and 22:00-23:00 hours. Average traveled distance was 265.66 m/h (± 390.98 m/h). The maximum hourly distance was 2,760.25 m/h; with significant differences considering the hour of day (χ2 = 324.51, df 11, p < 0.001), with higher mean values between 00:00 and 08:00 h. The average distance covered by males was higher than females (Z –24.827, p < 0.001): 341.64 ± 440.03 m/h and 146.31 ± 259.04 m/h respectively. Significant differences considering seasons were found (Z = –16.442, p < 0.001): average distance during the dry season was 230.35 ± 365.87 m/h and was higher during the rainy season: 337.082 ± 430.45 m/h. Differences according to season were also consistent considering males and females separately (males: Z = –6.212, p < 0.001; females: Z = –15.801, p < 0.001). Occupation model analysis revealed that two of the five pairs of species (P. onca and P. tajacu and P. onca and C. paca) occur with more frequency than if they were independent, while in terms of co-detection, P. onca and P. tajacu and P. onca and C. paca showed independence

scholarly journals Movement patterns of juvenile Atlantic tarpon (Megalops atlanticus) in Brewers Bay, St. Thomas US Virgin Islands

2021 ◽  
Author(s):  
Mareike Donaji Duffing Romero ◽  
Jordan K. Matley ◽  
Jiangang Luo ◽  
Jerald S. Ault ◽  
Simon J. Pittman ◽  
...  
Keyword(s):  
Habitat Use ◽  
Large Scale ◽  
Economic Value ◽  
Movement Ecology ◽  
Movement Patterns ◽  
Virgin Islands ◽  
Food Sources ◽  
Small Scale ◽  
Megalops Atlanticus ◽  
Atlantic Tarpon

Abstract Background Atlantic tarpon (Megalops atlanticus) are a highly migratory species ranging along continental and insular coastlines of the Atlantic Ocean. Due to their importance to regional recreational and sport fisheries, research has been focused on large-scale movement patterns of reproductively active adults in areas where they are of high economic value. As a consequence, geographically restricted focus on adults has left significant gaps in our understanding of tarpon biology and their movements, especially for juveniles in remote locations where they are common. Our study focused on small-scale patterns of movement and habitat use of juvenile and subadult tarpon using acoustic telemetry in a small bay in St. Thomas, U. S. Virgin Islands. Results Four juvenile tarpon (80 – 95 cm FL) were tracked from September 2015 to February 2018, while an additional eight juveniles (61 – 94 cm FL) left the study area shortly after tagging and were not included in analysis. The four resident tarpon had >78% residency and average activity space of 0.76 km2 (range = 0.08-1.17 km2) within Brewers Bay (1.8km2). Their vertical distribution was <18 m depth with occasional movements to deeper water. Activity was greater during day compared to night, with peaks during crepuscular periods. During the day tarpon used different parts of the bay with consistent overlap around the St. Thomas airport runway and at night tarpon typically remained in a small shallow lagoon. However, when temperatures in the lagoon exceeded 30 °C, tarpon moved to cooler, deeper waters outside the lagoon. Conclusion Our results, although limited to only four resident fish, provides new baseline data on the movement ecology of juvenile Atlantic tarpon. We showed that juvenile tarpon had high residency within a small bay and relatively stable non-overlapping daytime home ranges, except when seasonally abundant food sources were present. Fine-scale acoustic tracking for over a year showed the effects of extreme environmental conditions on tarpon movement and habitat use. These observations highlight the need for more extensive studies of juvenile and subadult tarpon across a broader range of their distribution, and compare the similarities and differences in behavior among various size classes of individuals from small juveniles to reproductively mature adults.

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