Hunting strategy for multi-robot based on wolf swarm algorithm and artificial potential field

The cooperation and coordination in multi-robot systems is a popular topic in the field of robotics and artificial intelligence, thanks to its important role in solving problems that are better solved by several robots compared to a single robot. Cooperative hunting is one of the important problems that exist in many areas such as military and industry, requiring cooperation between robots in order to accomplish the hunting process effectively. This paper proposed a cooperative hunting strategy for a multi-robot system based on wolf swarm algorithm (WSA) and artificial potential field (APF) in order to hunt by several robots a dynamic target whose behavior is unexpected. The formation of the robots within the multi-robot system contains three types of roles: the leader, the follower, and the antagonist. Each role is characterized by a different cognitive behavior. The robots arrive at the hunting point accurately and rapidly while avoiding static and dynamic obstacles through the artificial potential field algorithm to hunt the moving target. Simulation results are given in this paper to demonstrate the validity and the effectiveness of the proposed strategy.

How fishing cats Prionailurus viverrinus Bennett, 1833 fish: describing a felid’s strategy to hunt aquatic prey

The fishing cat’s persistence in a ‘semi-aquatic niche’ suggests the evolution of a successful hunting strategy. We describe it for the first time by analysing 197 camera-trap video-clips, collected from a participatory-science initiative, within an ethogram framework. The cats spent ∼52% of the time sitting and waiting for prey (fishes) to come nearer and took limited attempts to hunt (3.89%) in deeper waters (in which the upper portions of the cat’s body were submerged), where its hunting success was found to be 42.86%. In shallow waters, it adopted a predominantly active mode of hunting (∼96%) to flush out prey.

Foraging and scavenging behaviour of the prairie rattlesnake (Crotalus viridis): no evidence that envenomation cues facilitate kleptoparasitism of struck prey

Most viperids are ambush predators that primarily use venom to subdue prey, employing a strike-release-trail hunting strategy whereby snakes follow the unique scent of envenomated prey to locate carcasses they have bitten and released. In addition to killing prey, rattlesnakes (like most carnivores) will also opportunistically scavenge carrion. This scavenging strategy likely includes the occasional consumption of carcasses killed by other snakes (i.e., kleptoparasitism). In areas with high densities of other pitvipers, utilizing the unique scent of animals envenomated by other snakes might be a viable alternative foraging strategy. We evaluated this possibility experimentally using a series of captive behavioural trials on prairie rattlesnakes (Crotalus viridis) to determine whether conspecific or heterospecific (C. scutulatus, C. ornatus) envenomation cues might increase the likelihood of kleptoparasitism. Rattlesnakes did not prefer envenomated prey over nonenvenomated prey, nor did they prefer venom cues of one species over another. Although they did frequently scavenge carcasses, in the absence of striking, snakes generally located carcasses using random searching movements instead of scent trails. Additionally, the amount of time rattlesnakes spent investigating carcass trails did not differ significantly among treatments, suggesting that striking, and the resultant formation of a chemical search image of prey, is more crucial to trailing behaviour than venom cues. Moreover, a high degree of behavioural variation among individuals was observed, suggesting that scavenging and kleptoparasitism in rattlesnakes is more complex than previously realized, and making generalizations about these behaviours is challenging.

Searching for Gamma-Ray Binaries in Multiwavelength Catalogs

The number of gamma-ray binaries currently known is still so small that even a new finding represents a significant expansion of its population. We present a possible hunting strategy based on screening different catalogs to filter potential peculiar stars consistent with gamma-ray sources whose association at lower energies is not yet certain. So far, two candidate systems have emerged from this process; we report about them here.

Variation in the sacroiliac joint in Felidae

Felidae species show a great diversity in their diet, foraging and hunting strategies, from small to large prey. Whether they belong to solitary or group hunters, the behavior of cats to subdue resisting small or large prey presents crucial differences. It is assumed that pack hunting reduces the per capita risk of each individual. We hypothesize that the sacroiliac articulation plays a key role in stabilizing the predator while subduing and killing prey. Using CT-scan from 59 felid coxal bones, we calculated the angle between both iliac articular surfaces. Correlation of this inter-iliac angle with body size was calculated and ecological stressors were evaluated on inter-iliac angle. Body size significantly influences inter-iliac angle with small cats having a wider angle than big cats. Arboreal species have a significantly larger angle compared to cursorial felids with the smallest value, and to scansorial and terrestrial species with intermediate angles. Felids hunting large prey have a smaller angle than felids hunting small and mixed prey. Within the Panthera lineage, pack hunters (lions) have a larger angle than all other species using solitary hunting strategy. According to the inter-iliac angle, two main groups of felids are determined: (i) predators with an angle of around 40° include small cats (i.e., Felis silvestris, Leopardus wiedii, Leptailurus serval, Lynx Canadensis, L. rufus; median = 43.45°), the only pack-hunting species (i.e., Panthera leo; median = 37.90°), and arboreal cats (i.e., L. wiedii, Neofelis nebulosa; median = 49.05°), (ii) predators with an angle of around 30° include solitary-hunting big cats (i.e., Acinonyx jubatus, P. onca, P. pardus, P. tigris, P. uncia; median = 31.80°). We suggest different pressures of selection to interpret these results. The tightening of the iliac wings around the sacrum probably enhances big cats’ ability for high speed and large prey control. In contrast, pack hunting in lions reduced the selective pressure for large prey.

Exponential distribution of velocities and power distribution of quiescent periods in the spontaneous movement patterns of three hunting spiders

Here, we investigate the spontaneous locomotor patterns in three spiders with different hunting strategies. The locomotor activity of adult wolf spiders Pardosa amentata, with a sit-and-move hunting strategy, has previously been demonstrated to follow strictly mathematical rules, with most time spent at lower velocities and exponentially decreasing time spent at increasing velocities. Likewise, they have an abundance of short quiescent (resting) periods following a power decay function towards longer quiescent periods. In the present study, we explored whether similar distributions were expressed in juveniles of P. amentata and in two other spider species with different hunting strategies: the sit-and-wait spider Xysticus cristatus and the actively searching sac spider Clubiona phragmitis. We found that all three spider species followed the same two general rules of movement. However, there were differences among the three species. On a logarithmic scale of exponential velocities and a double-logarithmic scale of the rest power decay function, the slopes of the lines for the three species differed. We propose that these differences reflect the behavioural and locomotor differences of the three hunting strategies. Furthermore, we compare our results with similar movement distributions in single cells, fruit flies, mice and even humans.

Group hunting in harbour porpoises

Cooperative hunting involves individual predators relating in time and space to each other’s actions to more efficiently track down and catch prey. The evolution of advanced cognitive abilities and sociality in animals are strongly associated with cooperative hunting abilities, as has been shown in lions, chimpanzees and dolphins. Much less is known about cooperative hunting in seemingly unsocial animals, such as the harbour porpoise (Phocoena phocoena Linnaeus, 1758). Using drones, we were able to record 159 hunting sequences of porpoises, out of which 95 sequences involved more than one porpoise. To better understand if the harbour porpoises were individually attracted by the fish school or formed an organized hunting strategy, the behaviour of each individual porpoise in relation to the targeted fish school was analysed. The results indicate role specialization, which is considered the most sophisticated form of collaborative hunting and only rarely seen in animals. Our study challenges previous knowledge about harbour porpoises and opens up for the possibility of other seemingly non-social species employing sophisticated collaborative hunting methods.