A comparative analysis of animal behavior (e.g., male vs. female groups) has been widely used to elucidate behavior specific to one group since pre-Darwinian times. However, big data generated by new ...sensing technologies, e.g., GPS, makes it difficult for them to contrast group differences manually. This study introduces DeepHL, a deep learning-assisted platform for the comparative analysis of animal movement data, i.e., trajectories. This software uses a deep neural network based on an attention mechanism to automatically detect segments in trajectories that are characteristic of one group. It then highlights these segments in visualized trajectories, enabling biologists to focus on these segments, and helps them reveal the underlying meaning of the highlighted segments to facilitate formulating new hypotheses. We tested the platform on a variety of trajectories of worms, insects, mice, bears, and seabirds across a scale from millimeters to hundreds of kilometers, revealing new movement features of these animals.
Investigating the locomotion mechanisms of animals improves our understanding of both their inherent movements and responses to external stimuli. Moreover, identifying the movement patterns of ...animals reveals their foraging search efficiency. The navigational mechanisms of foraging ants have been well studied; they present typical search strategies for pinpointing their goal. However, the detailed movement patterns of ants and the properties of their exploratory behaviors have yet to be fully studied, perhaps because of the inherent difficulty in investigating ants on a restricted flat field (on which they tend to walk along walls and stop moving around corners). Here, we address this problem using a spherical treadmill system (ANTAM), and we use this system to investigate the diffusiveness of Japanese wood ants’ movements. On the treadmill, the ants walked over long distances without any restrictions. We found that the diffusiveness of movements varied across individuals and depended on time. Interestingly, further analysis indicated that the evolution of individual walkers’ travel paths exhibited pink noise, even if individuals apparently produced different types of trajectories. Such complex paths may be related to optimized search strategies since ants produced both small and long paths unpredictably.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
In this study, we describe the development of a behavioral trajectory measurement system called Bucket-ANTAM to measure the behavior of organisms when moving on a two-dimensional plane. The ...Bucket-ANTAM system detects the center-of-gravity movement of the target organism through a camera-based image analysis and controls a Dynamixel MX-106 servo motor with an attached omni-wheel to realize the function required to track the organism. We investigated the negative phototaxis of pill bugs (
Armadillidium vulgare
) using the developed Bucket-ANTAM to evaluate its usefulness. We conducted an experiment in which the pill bugs were reared in a simulated day/night environment using a light source, where the pill bugs were subjected to light stimulation from one direction only. The results of this experiment demonstrated that the pill bugs migrated more quickly under the night-time conditions than under the daytime conditions and that the pill bugs under the night-time conditions were more likely to express negative phototaxis.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Tracking animal movements such as walking is an essential task for understanding how and why animals move in an environment and respond to external stimuli. Different methods that implemented image ...analysis and a data logger such as GPS have been used in laboratory experiments and in field studies, respectively. Recently, animal movement patterns without stimuli have attracted an increasing attention in search for common innate characteristics underlying all of their movements. However, it is difficult to track the movements in a vast and homogeneous environment without stimuli because of space constraints in laboratories or environmental heterogeneity in the field, hindering our understanding of inherent movement patterns. Here, we applied an omnidirectional treadmill mechanism, or a servosphere, as a tool for tracking two-dimensional movements of small animals that can provide both a homogenous environment and a virtual infinite space for walking. To validate the use of our tracking system for assessment of the free-walking behavior, we compared walking patterns of individual pillbugs (Armadillidium vulgare) on the servosphere with that in two types of experimental flat arenas. Our results revealed that the walking patterns on the servosphere showed similar diffusive characteristics to those observed in the large arena simulating an open space, and we demonstrated that our mechanism provides more robust measurements of diffusive properties compared to a small arena with enclosure. Moreover, we showed that anomalous diffusion properties, including Lévy walk, can be detected from the free-walking behavior on our tracking system. Thus, our novel tracking system is useful to measure inherent movement patterns, which will contribute to the studies of movement ecology, ethology, and behavioral sciences.
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In swarm robotics, communication among the robots is essential. Inspired by biological swarms using pheromones, we propose the use of chemical compounds to realize group foraging behavior in robot ...swarms. We designed a fully autonomous robot, and then created a swarm using ethanol as the trail pheromone allowing the robots to communicate with one another indirectly via pheromone trails. Our group recruitment and cooperative transport algorithms provide the robots with the required swarm behavior. We conducted both simulations and experiments with real robot swarms, and analyzed the data statistically to investigate any changes caused by pheromone communication in the performance of the swarm in solving foraging recruitment and cooperative transport tasks. The results show that the robots can communicate using pheromone trails, and that the improvement due to pheromone communication may be non-linear, depending on the size of the robot swarm.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Complex biological systems resemble a “black box,” as it is a priori unclear how interactions among individuals will affect the collective (group) behavioral performance. Network analysis is a ...suitable method to shed light on these black boxes by studying the collective behavior of highly integrated social organisms such as ants. Individual within the colony have their own personality and task allocation for sustaining the society. Individual-level data are also important for understanding network structure. To obtain individual-level data such as personality and task allocation, individual behavior was assessed using several well-established information processing methods. To detect individual personalities from the position data, trajectory patterns were used. To analyze trajectory patterns, behavioral motif detection was used. The behavioral motif is the minimum unit of the entire trajectory.
Death feigning (or tonic immobility) is an effective antipredator strategy. However, prolonged immobility on the ground increases the risk of being parasitized or eaten by predators, and thus, ...insects must rouse themselves when appropriate stimulation is provided. Very few studies on the effect of stimulus intensity on arousal from death feigning have been conducted. A previous study using
Tribolium castaneum
showed an existing threshold for the intensity of the stimulus that causes arousal from death feigning. Whether there are differences between species in the threshold for arousal is an interesting question. In the present study, we, therefore, compared the effect of stimulus strength on arousal from death feigning in two closely related species, namely,
T. confusum
and
T. freemani
, which are established strains that have been artificially selected for longer duration of death feigning. Also, part of the study was to determine whether there was a positive association between intensity of stimulus needed to rouse and the duration of death feigning. We discuss why there is a difference in the strength of the stimulus needed for arousal from death feigning among
Tribolium
species, for which we included the data for
T. castaneum
from a previous study.
The recruiting system in foraging ant colonies is a typical example of swarm intelligence. The system is underpinned by the use of volatile pheromones which form a trail connecting from nest to food. ...We have incorporated this property into the behavior of the swarm of real robots. Because the trail is narrow, avoiding overcrowding on the trail, as well as in the environment, is a critical issue in maintaining efficiency of the swarm behavior. In this paper, we studied how “priority rule,h a behavioral rule under which a robot is given priority over the other robot in collision, affect the group-foraging performance of pheromone-mediated swarm robots. Using real robot experiments, we found that the alteration in the priority rules can have substantial effects on the group-foraging performance. Our results highlight the importance of implementing “fine-tuningh algorithms to improve the performance of complex swarm systems.
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