{{Short description|Ability of dogs to recognize and follow a specific scent}} [[File:Male Weimeraner Following a Scent Trail in the Snow.jpg|thumb|Male Weimeraner following a scent trail in the snow]] '''Tracking''' refers to a dog's ability to detect, recognize and follow a specific scent. Possessing heightened olfactory abilities, dogs, especially scent hounds, are able to detect, track and locate the source of certain odours.<ref name="Hepper 2005">Hepper, P. G., & Wells, D. L. (2005). How many footsteps do dogs need to determine the direction of an odour trail?. Chemical Senses, 30(4), 291–298.</ref> A deeper understanding of the physiological mechanisms and the phases involved in canine scent tracking has allowed humans to utilize this animal behaviour in a variety of professions.<ref name="Thesen 1993" /> Through domestication and the human application of dog behaviour, different methods and influential factors on tracking ability have been discovered. While tracking was once considered a predatory technique of dogs in the wild, it has now become widely used by humans.
== Physiological mechanisms == thumb|Close-up picture of a dog's nose. According to zoosemiotics animal communication involves an exchange of information between a sender and a receiver through a transfer of chemical signs. Described as representation and signification, a chemical sign can be produced without the presence of a dog and detected without the presence of the individual who produced it.<ref name="Gadbois 2014">Gadbois, S., & Reeve, C. (2014). Canine olfaction: scent, sign, and situation. In Domestic dog cognition and behavior (pp. 3–29). Springer, Berlin, Heidelberg.</ref> This means dogs have the ability to leave their own signs and detect previously laid signs without the presence of another dog or individual. It is this theory of zoosemitoics that explains how dogs are able to determine the direction of a seemingly invisible scent track.
Although dogs are capable of following both visual and olfactory cues, it appears that scent is their most effective source of information.<ref name="Steen 1990">Steen, J. B., & Wilsson, E. (1990). How do dogs determine the direction of tracks?. Acta Physiologica Scandinavica, 139(4), 531–534.Chicago</ref> Equipped with enhanced physical and neurological olfactory structures, dogs have a much more advanced sense of smell than humans.<ref name="Weakley 2005">Weakley-Jones, B., & Rebmann, A. J. (2005). DOGS, USE IN POLICE INVESTIGATIONS. In Editor-in-Chief: Jason Payne-James (Ed.), Encyclopedia of forensic and legal medicine (pp. 221–223). Oxford: Elsevier.</ref> Specialized turbinate bones in the canine nasal cavity allow for increased exposure of chemical receptor cells to the air.<ref name="Taslitz 1990">Taslitz, A. E. (1990). Does the Cold Nose Know—The Unscientific Myth of the Dog Scent Lineup. Hastings LJ, 42, 15.</ref> This, paired with a proportionally large segment of brain devoted to olfaction processing, results in the enhanced smelling ability of canines.<ref name="Taslitz 1990" />
Both physical and neurological attributes of dogs contribute to their ability to detect extremely small concentrations of specific scents and their ability to differentiate between odours. The accuracy of these detections is determined by the concept of scent groups.<ref name="Taslitz 1990" /> A scent group refers to a specific mixture of scents that comprise the overall odour of an individual.<ref name="Taslitz 1990" /> A dog's acuity to a scent group is so refined they are able to discriminate humans by odour<ref>Settle, R. H., Sommerville, B. A., McCormick, J., & Broom, D. M. (1994). Human scent matching using specially trained dogs. Animal Behaviour, 48(6), 1443–1448.</ref> and can even match certain scents to specific body parts of an individual.<ref name="Berns 2015">Berns, G. S., Brooks, A. M., & Spivak, M. (2015). Scent of the familiar: An fMRI study of canine brain responses to familiar and unfamiliar human and dog odors. Behavioural processes, 110, 37–46.</ref> Scent discrimination is most proficient while a human odour is fresh and becomes more difficult once an odour starts to fade.<ref name="Taslitz 1990" />
== Phases == Tracking behaviour in dogs is exhibited through three separate phases.<ref name="Thesen 1993" />
===Searching Phase===
* Initial period in which dogs attempt to find a track. Dogs sniff very quickly ten to twenty times between inhalations of breath.<ref name="Thesen 1993">Thesen, A., Steen, J. B., & Doving, K. B. (1993). Behaviour of dogs during olfactory tracking. Journal of Experimental Biology, 180(1), 247–251.</ref> Sniff frequency is usually 6 Hz<ref>{{Cite journal|last1=Porter|first1=Jess|last2=Craven|first2=Brent|last3=Khan|first3=Rehan M|last4=Chang|first4=Shao-Ju|last5=Kang|first5=Irene|last6=Judkewitz|first6=Benjamin|last7=Volpe|first7=Jason|last8=Settles|first8=Gary|last9=Sobel|first9=Noam|date=2006-12-17|title=Mechanisms of scent-tracking in humans|journal=Nature Neuroscience|volume=10|issue=1|pages=27–29|doi=10.1038/nn1819|pmid=17173046|issn=1097-6256}}</ref> and occurs while the dog is in motion looking for a trail.
===Deciding Phase===
* Track identification is apparent when the dog halts and then proceeds to take smaller step and the sniffing frequency of the dog becomes much longer. * Period usually lasts 3–5s<ref name="Thesen 1993" />
===Tracking Phase===
* Similar to the searching phase. Sniffing behaviour and walking behaviour become quicker.
== Methods == left|thumb|217x217px|Bloodhound on a field scent trail Although dogs use physiological methods to detect scent trails, they apply these methods differently depending on the environments in which they are tracking.<ref name= "Berns 2015" /> A scent results from the individual odour of a person being tracked or through an environmental disturbance odour that results from the physical movements of the person being tracked.<ref name="Hepper 2005"/> The ways in which dogs track an individual, vegetative and track scent can vary depending on circumstances. Specifically, scent tracking ability of a dog depends on whether or not an individual deposits their scent in the air or on the ground.
'''An air scent''' is when human odours of sweat, cells, gland secretions, or toiletries circulate freely in the open air.<ref name= "Taslitz 1990" /> The bacteria attached to fallen skin cells provide dogs with odorous by-products that enhance the individuality of a trail.<ref name = "Taslitz 1990" /> While an initial air scent is much stronger than a ground scent, a ground scent remains detectable for a longer period of time.<ref name ="Taslitz 1990" />
'''A ground scent''' is the combined permeations of trampled vegetation, bugs, mud, and soil disturbed by an individual's footprints.<ref name ="Taslitz 1990" /> The disturbed soil releases moisture and kills plant life which results in a different odorous by-product.<ref name ="Taslitz 1990" /> Each footprint releases a new odour more potent than the ones of the undisturbed vegetation surrounding it.
'''A track scent''' is often a mixture of both the air scent and the ground scent being left behind by an individual.<ref name ="Taslitz 1990" /> Dogs are able to determine a track scent by identifying a combination of both human odours and environmental odours released by an individual. They then use the strength of this overall scent to determine the directionality of a trail and track along that route.<ref name= "Steen 1990" /> Since an initial footstep is much less potent than the last footstep taken by an individual, dogs move in the direction where the scent seems to become stronger.<ref name = "Steen 1990" /> Additionally, dogs have been observed to alternate between visual tracking and scent tracking depending on the circumstances of their environment. For the most part dogs prefer to use olfactory cues even when the target or visual cues are within their line of sight.<ref name= "Gazit 2003">Gazit, I., & Terkel, J. (2003). Domination of olfaction over vision in explosives detection by dogs. Applied Animal Behaviour Science, 82(1), 65–73.</ref> However, there has been research conducted where dogs have been shown to rely on visual, social or cognitive cues to identify the tracks of an individual.<ref>Dumas, C. (1998). Figurative and spatial information and search behavior in dogs (Canis familiaris). Behavioural Processes, 42(2–3), 101–106.</ref>
== Factors that influence tracking ability ==
[[File:French Urban Search and Rescue.jpg|thumb|A member of search and rescue and his dog looking for survivors in the aftermath of 9/11. |279x279px]]There are many different factors which influence a dog's ability to successfully determine the directionality of a track. The age, sex,<ref name="Hepper 2005"/> and even personality<ref name="Svartberg 2002">Svartberg, K. (2002). Shyness–boldness predicts performance in working dogs. Applied Animal Behaviour Science, 79(2), 157–174.</ref> of a dog can greatly influence tracking behaviour. Male dogs have been said to more accurately determine the direction of a trail than female dogs.<ref name="Hepper 2005"/> It is hypothesized that this is due to the evolutionary history of male dogs. Male olfactory ability of canines is superior to that of females because historically it was their duty to find mates and mark territory.<ref name="Hepper 2005"/> Canine olfactory sensitivity is also found to diminish, therefore younger dogs tend to have superior tracking to that of older dogs.<ref name="Hepper 2005"/> Personality traits of dogs affect both their ability to be successfully trained and their ability to successfully track. Dogs that are more active and confident tend to perform better during training activities and tracking activities.<ref name="Svartberg 2002" />
The mannerisms of the handler<ref name="Furton 2001" /> working with the dog can also affect tracking ability. It has been discovered that humans and animals share very specific social skills that enable them to bond and work together effectively.<ref name= "miklosi 2013">Miklósi, Á., & Topál, J. (2013). What does it take to become ‘best friends’? Evolutionary changes in canine social competence. Trends in cognitive sciences, 17(6), 287–294</ref> Adaptations of social tolerance and attentiveness has enabled dogs to participate in cooperative problem solving with their human counterparts.<ref>Ostojić, L., & Clayton, N. S. (2014). Behavioural coordination of dogs in a cooperative problem-solving task with a conspecific and a human partner. Animal cognition, 17(2), 445–459.</ref> Social attentiveness refers to an animal's ability to pay attention to their partner's actions and behave accordingly.<ref name= "Range 2015">Range, F., & Virányi, Z. (2015). Tracking the evolutionary origins of dog-human cooperation: the “Canine Cooperation Hypothesis”. Frontiers in psychology, 5, 1582.</ref> It is this factor that explains how dogs are capable of interpreting and reacting to cues from their handler. Pointing, gaze shifting, and facial expressions demonstrated by the handler can be used by the canine to locate objects and follow a certain direction.<ref name= "miklosi 2013" /> Canines are even able to interpret the unconscious signals of the humans they work with. Therefore, handlers are trained to be cautious of their actions in order to ensure their demands are being properly perceived by the dog.<ref name= "miklosi 2013" />
== Human uses of tracking dogs == left|thumb|292x292px|Police dog performing a search for explosives Human uses for tracking dogs are dependent on many different factors. Specifically, the demands of a job often influence which kind of dog humans choose to train and employ. There are three different types of scenting dogs based on their affinity for air scents, ground scents and tracking scents.<ref name= "Taslitz 1990" /> Categorized as tracking dogs, trailing dogs, and point source dogs,<ref name= "Taslitz 1990" /> each one specializes in a different method of tracking.
=== Tracking dogs === Tracking dogs are known for their ability to detect and follow the vegetative vapours released from disturbances of plant life.<ref name= "Taslitz 1990" /> They stay very close to foot paths and are able to follow considerably aged tracks.<ref name= "Taslitz 1990" />
=== Trailing dogs === Trailing dogs have a stronger affiliation for proponents of human scent near the trail they are tracking.<ref name= "Taslitz 1990" /> They can be observed deviating slightly from or crossing over the trail they are tracking.<ref name= "Taslitz 1990" /> Trailing dogs heavily rely on scent because the trails they follow often do not have any visual cues for tracking. Tracking and trailing dogs are often used interchangeably for police aid in human, suspect and victim searches.
=== Point source dogs === thumb|German shepherd sniffing out a possible bomb
Point source dogs are specialized in air scent tracking and tend to ignore ground scents. They utilize increasing intensity of specific odours to identify and track a trail to a certain target object. There are two separate classifications of point source dogs: detector dogs<ref name= "Taslitz 1990" /> and discrimination dogs.<ref name= "Taslitz 1990" /> Detection dogs are most often used to identify both non-biological and biological scents of a target object while ignoring other non-target environmental scents.<ref name= "Browne 2006">Browne, C., Stafford, K., & Fordham, R. (2006). The use of scent-detection dogs. Irish Veterinary Journal, 59(2), 97.</ref> Discrimination dogs are most often employed by police forces to identify the scent of a specific individual being tracked. This differs from detection dogs because they are required to react to a scent that matches or differentiates between other ones instead of identifying that a certain scent is present.<ref name= "Taslitz 1990" />
Specific uses of detection dogs
* Explosive and mine identification<ref name= "Browne 2006" /> * Bacteria detection in buildings and homes<ref>Kauhanen, E., Harri, M., Nevalainen, A., & Nevalainen, T. (2002). Validity of detection of microbial growth in buildings by trained dogs. Environment international, 28(3), 153–157.</ref> * Detection of human waste materials in storm drains<ref>Van De Werfhorst, L. C., Murray, J. L., Reynolds, S., Reynolds, K., & Holden, P. A. (2014). Canine scent detection and microbial source tracking of human waste contamination in storm drains. Water Environment Research, 86(6), 550–558.</ref> * Search and rescue missions,<ref name="Weakley 2005" /> recovering evidence from a crime scene,<ref name="Baldwin 2000">Baldwin, H. B., & Puskarich May, C. (2000). CRIME-SCENE INVESTIGATION AND EXAMINATION | recovery of human remains. In Editor-in-Chief: Jay A. Siegel (Ed.), Encyclopedia of forensic sciences (pp. 447–457). Oxford: Elsevier.</ref> and locating drugs<ref name= "Furton 2001" /> and explosives<ref name="Baldwin 2000" />
Specific uses of discrimination dogs * Finding dead<ref name= "Weakley 2005" /> or alive<ref name= "Furton 2001">Furton, K. G., & Myers, L. J. (2001). The scientific foundation and efficacy of the use of canines as chemical detectors for explosives. Talanta, 54(3), 487–500.</ref> police suspects * Distinguishing between different forms of narcotics<ref name="Taslitz 1990" /> and reacting to the presence of a specific narcotic
== Tracking trials == left|thumb|Tenterfield terrier in a tracking trial A '''Tracking trial''' is an event to encourage dogs to make use of their strongest facility, the ability to follow a scent trail. The competition emulates the finding of a lost person or article in a situation where the performance of the dog can be fairly assessed. Because of this, the tracks laid are straightforward, not the wanderings that may characterize a lost person, nor do they include deliberate attempts by the tracklayer to deceive the dog.
Although different organizations specify somewhat different rules, the basics of a tracking trial remain the same. The objective is for the dog to find the deliberately "lost" tracklayer and any articles they may have dropped along the track.<ref>{{Cite web|title=Tracking|url=https://www.dogsnsw.org.au/events/tracking/|access-date=2021-03-20|website=www.dogsnsw.org.au}}</ref><ref>{{Cite web|title=Tracking|url=https://www.akc.org/sports/tracking/|access-date=2021-03-20|website=American Kennel Club|language=en}}</ref>
Generally, tracks are laid, marked, and mapped on the day previous to the tracking trial by the trial judge or steward. Tracks are chosen so that the judge or steward can easily determine where the track is located, and where articles are to be placed, even after the marks, ribbons, or flags have been removed. The length of the track, the number of corners, the number of articles left on the track depends on the level of difficulty of the track and the rules of the organization under which the trial is being run. thumb|222x222px|A Belgian Malinois at a Schutzhund trial during tracking phase On the day of the trial, a tracklayer follows the marked track and removes any marks that have been placed on the track, then leaves articles of clothing on the track as specified by the steward or judge, including one at the end of the track. After a specified time, depending on the difficulty of the track and the requirements of the rules of the organization, the dog and handler is directed to the track and find the tracklayer and articles as required. The dog is usually worked on a 10-meter or (30-foot) lead, but the length of lead actually used depends on the terrain.
In general, a dog must work continually as if genuinely looking for a lost person without assistance from the handler, and find the required number of lost articles and the tracklayer at the end of the track, for the dog to be awarded a pass. This pass can also be graded on the quality of the work. After the required passes have been awarded, the dog may apply for a tracking title according to the rules of the organization the trials have been run under.<ref>{{Cite web|last=AUSTRALIAN NATIONAL KENNEL COUNCIL LTD|title=Rules for the conduct of Tracking Trials|url=http://ankc.org.au/media/1097/295832tracking_2014.pdf}}</ref>
== See also == * Scent hound
== References == {{reflist}}
{{Dog sports}}
Category:Dog sports Category:Olfaction Category:Scent hounds