scent theory en
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SCENT THEORY
Presented by Kris BlackCSSTand
Santa Clara County Sheriff Search and Rescue
Adaptations and Illustrations from the Cadaver Dog Handbook
Topics• Olfactory system• Raft Theory • Scent Theory• Ground Scent Picture• Air/Scent movement• Summary • Practical Applications
Canine Olfactory• 125 – 400 million olfactory cells• 1/8 of canine brain devoted to olfactory• 44 times more receptors (man has 5 million)• smell memory 8 times greater
Portion of our brain devoted to scent
Portion of the canine brain devoted to scent
Dachshund - 125 million receptor cells
Greater capacity for scent work
Fox Terrier - 147 million receptor cells German Shepherd - 225 million receptor cells
R.S. Eden and Eden Consulting Group
Limited capacity for scent work
CONSIDER THE TOOL
Raft TheoryBill Syrotuck
• raft = group of cells• rafts = 14 microns / same as
smoke• body gives off heat • skin cells shed constantly• 40,000/min• bacteria break down cell
proteins• cell proteins float• currents move rafts upward
Theoretical Scent Pictures
No Wind
Wind
.
Sun
Clouds
Coning Plume• What most people are familiar with• Stable Air• Early mornings, late afternoons just before
sunset• Spreads out in a Horizontal 3 dimensional
cone carried downwind of the subject • Best scenting condition
Coning Plume
Ground Scent• Cold drops scent to ground• Sticks to crushed vegetation• Settles in disturbed earth
WIND
Thermal Lift
Looping Plume
• Occurs in very hot unstable air• Convection causes scent to rise up then drop
back down• Record time and wind direction• Need to check upper wind to help find new
search area
Looping Plume
Fanning Plume• Occurs in early morning, usually just before
sunrise on calm and clear nights.• In winter-scent rises till hits 86 degree layer• The scent cone compresses vertically and
fans out horizontally• May be over dogs head• May only hit scent on hills• Look for same height hills
Fanning Plume
WIND
Fumigating• Occurs in the morning when the air is still cool• As the sun begins warming the earth, the warm “unstable” air
rises and meets the cool air• Same as fanning, but where warm meets cold, the scent drops
to ground .
WIND
Lofting• Opposite of fumigating• Occurs when ground is cooling as the sun goes down• Warm air is still aloft• Scent travels up and spreads out• Employ “high ground” strategy
Lofting
Eddying• Occurs when scent is transported across
/ around a sharp corner
• Concentration of scent gets trapped in a circular turbulence
• Think of leaves in an entryway
EddyingWIND
Primary and Secondary Scent Pools
1 represents the primary pool 2 represents the secondary pool
Ground Water Flow
1 represents the primary pool 2 represents the secondary pool
Down Hill
1 represents the primary pool 2 represents the secondary pool
Hanging
Variable Winds
Tree LineWIND
Scent and Water
Water search
A represents the dog’s alert or indication
A REVIEW – if the sky is clear• Night = Fanning
• 1/2 hour before sunrise = Fumigating
• Daytime = Looping
• Sundown = Lofting
• At night with clouds and no inversion layer = Coning
A REVIEW – if it is cloudy• the scent is held down and closer to the ground
• clear skies cause scent to rise straight up from body
• clouds being high, medium, or low determines air stability
Summary• Rafts and decomp material fall constantly and are
effected by wind, temp, terrain, humidity
• Employee effective search techniques, keeping in mind the factors that effect the scent picture
• Continue to educate yourself on scent behavior and study your dogs reactions under various scenting conditions, so as to make yourself a more effective search team.