Sector search strategies for odor trail tracking

Ants, mice, and dogs often use surface-bound scent trails to establish navigation routes or to find food and mates, yet their tracking strategies remain poorly understood. Chemotaxis-based strategies cannot explain casting, a characteristic sequence of wide oscillations with increasing amplitude performed upon sustained loss of contact with the trail. We propose that tracking animals have an intrinsic, geometric notion of continuity, allowing them to exploit past contacts with the trail to form an estimate of where it is headed. This estimate and its uncertainty form an angular sector, and the emergent search patterns resemble a “sector search.” Reinforcement learning agents trained to execute a sector search recapitulate the various phases of experimentally observed tracking behavior. We use ideas from polymer physics to formulate a statistical description of trails and show that search geometry imposes basic limits on how quickly animals can track trails. By formulating trail tracking as a Bellman-type sequential optimization problem, we quantify the geometric elements of optimal sector search strategy, effectively explaining why and when casting is necessary. We propose a set of experiments to infer how tracking animals acquire, integrate, and respond to past information on the tracked trail. More generally, we define navigational strategies relevant for animals and biomimetic robots and formulate trail tracking as a behavioral paradigm for learning, memory, and planning.

Sector search strategies for odor trail tracking

Terrestrial animals such as ants, mice and dogs often use surface-bound scent trails to establish navigation routes or to find food and mates, yet their tracking strategies are poorly understood. Tracking behavior features zig-zagging paths with animals often staying in close contact with the trail. Upon sustained loss of contact, animals execute a characteristic sequence of sweeping “casts” – wide oscillations with increasing amplitude. Here, we provide a unified description of trail-tracking behavior by introducing an optimization framework where animals search in the angular sector defined by their estimate of the trail’s heading and its uncertainty.In silicoexperiments using reinforcement learning based on this hypothesis recapitulate experimentally observed tracking patterns. We show that search geometry imposes limits on the tracking speed, and quantify its dependence on trail statistics and memory of past contacts. By formulating trail-tracking as a Bellman-type sequential optimization problem, we quantify the basic geometric elements of optimal sector search strategy, effectively explaining why and when casting is necessary. We propose a set of experiments to infer how tracking animals acquire, integrate and respond to past information on the tracked trail. More generally, we define navigational strategies relevant for animals and bio-mimetic robots, and formulate trail-tracking as a novel behavioral paradigm for learning, memory and planning.

Working qualities of search dogs of German and Belgian shepherd breeds

The main tasks for which canine units of law enforcement agencies of Ukraine use search dogs are: inspection of various areas and search operations to identify persons who have committed or intend to commit offenses, their odors and things, detection of persons moving or hiding in the condition of limited visibility in the area; prosecution of offenders, their detention, protection and escort; inspection of trucks and localization of persons hiding in these vehicles; odorological identification of odorous traces of detainees and their belongings; strengthening the personal security of law enforcement officers during their service; psychological impact on offenders. The fundamentals for the active use of dogs in official activities are the physiological features of the olfactory analyser and the physical capabilities of the dog's body. The most common breeds used to perform the outlined tasks are: German shepherd, Bloodhound, Belgian shepherd (Malinois) and others. The article reflects the comparative characteristics of the working qualities of search dogs of German and Belgian (Malinois) shepherd dogs of different sexes and ages. The study was conducted on service dogs in the Canine Training Center of the State Border Guard Service of Ukraine located in Velyki Mosty, Sokal district, Lviv region. The working qualities of search dogs were assessed by the skills of obedience, protection, pursuit of a person on his odor trail, secure of the area and detection of a person hiding and moving, selection of odorous objects (things), search and detection of objects (things). It is fixed that the working qualities of search dogs are influenced by breed and sex. Among the males of the German and Belgian (Malinois) Shepherd breeds, the service dogs of the German Shepherd breed were noted for the best working qualities, and among the female – the Belgian Shepherd (Malinois) breeds. A generalized assessment of all four sections of the studied breeds showed that the best performance was in males of the German Shepherd breed (325.4 points) and females of the Belgian Shepherd breed (Malinois) (325.9 points), and among individuals of different sexes – males compared to females of the German Shepherd breed and females compared to males of the Belgian Shepherd (Malinois) breed. Two-year-old males and one-year-old females of the German shepherd breed and two-year-old females of the Belgian Shepherd breed (Malinois) were noted for the best working qualities in terms of skills to be evaluated. As for males of the last breed, their testing qualities almost did not depend on age. The strength of the influence of the breed of service dogs on their working qualities in the skills to be assessed ranged from 0.6 to 6.8 %, sex – from 0.1 to 7.3 % and age - from 0.1 to 11.4 %. The general assessment of service dogs in all sections was generally influenced by their age (1.6 %).

Carpenter ants use diverse antennae sampling strategies to track odor trails

Directed and meaningful animal behavior depends on the ability to sense key features in the environment. Among the different environmental signals, olfactory cues are critically important for foraging, navigation, and social communication in many species, including ants. Ants use their two antennae to explore the olfactory world, but how they do so remains largely unknown. In this study, we use high resolution videography to characterize the antennae dynamics of carpenter ants (Camponotus pennsylvanicus). Antennae are highly active during both tracking and exploratory behavior. When tracking, ants used several distinct behavioral strategies with stereotyped antennae sampling patterns (which we call sinusoidal behavior, probing, and trail following). In all behaviors, left and right antennae movements were anti-correlated, and tracking ants exhibited biases in the use of left vs right antenna to sample the odor trail. These results suggest non-redundant roles for the two antennae. In one of the behavioral modules (trail following), ants used both antennae to detect trail edges and direct subsequent turns, suggesting a specialized form of tropotaxis. Lastly, removal of an antenna resulted not only in less accurate tracking but also in changes in the sampling pattern of the remaining antenna. Our quantitative characterization of odor trail tracking lays a foundation to build better models of olfactory sensory processing and sensorimotor behavior in terrestrial insects.Summary StatementHigh resolution imaging of antennae reveals distinct patterns of sampling with non-redundant roles in odor tracking.

Mice follow odor trails using stereo olfactory cues and rapid sniff to sniff comparisons

Animals use the distribution of chemicals in their environment to guide behaviors essential for life, including finding food and mates, and avoiding predators. The presence of this general class of behavior is extremely widespread, even though the olfactory sensory apparatus and strategies used may vary between animals. The strategies and cues used by mammals to localize and track odor sources have recently become of interest to neuroscientists, but are still poorly understand. In order to study how mice localize odors, we trained mice to perform a trail following task using a novel behavioral paradigm and behavioral monitoring setup. We find that mice, in order to follow an odor trail, use both sniff by sniff odor concentration comparisons and internares comparisons to guide their behavior. Furthermore, they employ olfactory information to guide adaptive behaviors with remarkably short latencies of approximately 80ms. This study and its findings establish a rich, quantifiable olfactory localization behavior in mice that is amenable to physiological investigations and motivates investigation into the neural substrates of the identified olfactory cues.SignificanceMany animals, like rodents, rely heavily on their sense smell to guide them as they navigate their environment, to find food and mates and to avoid predators. Yet, in mammals, this function of the olfactory system is much less well studied than odor identification. We created a behavioral task where mice had to follow odor trails in order to efficiently find food and then tracked their movements around those trails. We found that they respond to sniff-by-sniff changes in odor intensity, using those changes to guide movements in less than one tenth of a second and also confirm that they use stereo cues to guide behavior. These results lay the groundwork for determining the brain circuits underlying olfactory navigation.

Observations on Forced Colony Emigration inParachartergus fraternus(Hymenoptera: Vespidae: Epiponini): New Nest Site Marked with Sprayed Venom

Five cases of colony emigration induced by removal of nest envelope and combs and a single one by manipulation are described. The disturbance was followed by defensive patterns, buzz running, and adult dispersion. An odor trail created by abdomen dragging, probably depositing venom or Dufour's gland secretions, connected the original nest to the newly selected nesting place and guided the emigration. The substrate of the selected nesting place is intensely sprayed with venom prior to emigration, and this chemical cue marked the emigration end point. The colony moves to the new site in a diffuse cloud with no temporary clusters formed along the odor trail. At the original nest, scouts performed rapid gaster dragging and intense mouth contacts stimulating inactive individuals to depart. Males were unable to follow the swarm. Individual scouts switched between different behavioral tasks before and after colony emigration. Pulp collected from the old nest was reused at the new nest site.