Table of Contents
Olfactory Predators and Odorants
Olfactory organs of vertebrates
Comparing the olfactory ability of humans to other mammals
Use of olfaction by birds to locate food
Which modality is most important to snakes in locating prey?
Which modality is most important to predatory mammals in locating prey?
Characteristics of odorants
Perception of odor mixtures
Sources of odorants from mammals and birds
Using odors to detect differences between species or individuals
Can animals hide from olfactory predators by changing their odor?
Can animals hide from olfactory predators by masking their odor with another, overpowering one?
Factors influencing the evaporation rate of odorants
Movement of odorants through the atmosphere
The olfactory concealment theory
Detecting and Locating Prey Through Depositional Odor Trails
Creation of depositional odor trails
Determining how long ago a trail was created
Determining the direction of an odor trail
Impact of environmental conditions on depositional odor trails
How good are predators at following a depositional odor trail?
Behavioral tactics used by deer and hares to escape from tracking dogs
Locating home ranges using olfactory cues
What prey can do to minimize their risk from depositional odor trails
What olfactory predators can do to maximize the usefulness of depositional odor trails
Using Airborne Odorants to Detect the Presence of Prey
The challenge of using airborne odorants to detect the presence of prey
Impact of a steady wind on a predator’s ability to detect an odor plume
How far can predators detect prey by sensing the quarry through its odor plume?
Can prey reduce their odorant emission rate?
Impact of wind velocity on odorant concentration
Impact of turbulence on odorant concentration
Differences in time-averaged and instantaneous views of odor plumes
Impact of lateral and vertical turbulence on the size of instantaneous odor plumes
Measurements of turbulence
Spatial and temporal structure of odor plumes
Effect of atmospheric instability on the vertical dispersion of odorants
Diurnal changes in atmospheric stability
Impact of atmospheric instability on olfactory predators and their prey
Using Odor Plumes to Locate Prey and the Impact of Convection
Locating prey through airborne odorants
Potential methods animals can use to locate an odor source
How moths locate sources of odor plumes
How tsetse flies use odor plumes to find their hosts
Do predators develop olfactory search images of their prey?
Impact of wind velocity on the ability of predators to locate prey using odor plumes
Impact of wind velocity of olfactory predators and their prey
Effect of variable wind speed and direction on use of odor plumes to locate prey
Convective turbulence caused by local topography
Impact of local convective currents on olfactory predators and their prey
Experimental Evidence that Updrafts and Turbulence Hinder the Ability of Predators to Find Prey Using Olfaction
Experiment 1: do updrafts and atmospheric turbulence hinder the ability of dogs to find birds?
Experiment 2: are nest predation rates by free-ranging predators lower in areas where updrafts occur?
Experiment 3: do updrafts and turbulence hinder the ability of free-ranging predators to find artificial nests?
Turbulence Caused by Isolated Surface Features
Mechanical turbulence caused by isolated surface features
Impact of turbulence caused by isolated surface features on olfactory predators and their prey
Mechanical turbulence caused by an isolated plant
Impact of turbulence caused by isolated trees on olfactory predators and their prey
Turbulence caused by shelterbelts
Impact of turbulence across shelterbelts on olfactory predators and their prey
Turbulence Over Rough Surfaces
Aerodynamic roughness length
Impact of z on olfactory predators and their prey
Airflow across habitat edges
Airflow from a Smooth to a Rough Surface
Airflow from Rough to Smooth Surfaces
Impact of turbulence caused by habitat edges on olfactory predators and their prey
Turbulence Within and Below Plant Canopies
Convective turbulence within plant canopies
Mechanical turbulence within plant canopies
Airflow and turbulence within forb and grass canopies
Movement of a pheromone plume within a grain field
Airflow within the subcanopy of forests
Differences in the movement of odor plumes above grass canopies and within forest canopies
How does turbulence within a forest plantation differ from a naturally reproducing or old-growth forest?
Impact of turbulence within a forest subcanopy on olfactory predators and their prey
Airflow in savannas
Impact of turbulence in forests, prairies, and savannas on olfactory predators and their prey
Trade-Offs Required to Achieve Optimal Hiding Strategies
Optimal hiding strategies for prey
Optimal foraging strategies for predators
How predators develop search images of prey
How birds learn where to nest
Interplay between a predator’s optimal foraging strategy and a prey’s optimal hiding strategy
Trade-offs involving avoiding detection versus capture
Trade-offs required to avoid both visual and olfactory predators
Trade-offs between the need to avoid olfactory predators and to meet the other necessities of life
Trade-offs between the need to reproduce this year versus during future years
Trade-offs involving the timing of dangerous activities
Trade-offs among injuries, illness, starvation, and predators
Impact of Olfactory Predators on the Behavior of Female Ungulates During Parturition and on the Behavior of Their Young
Do females reduce their production of odorants at parturition sites or the bedding sites of their young?
Is the behavior of neonates designed to hinder the ability of predators to find them using olfaction?
Do fawns adjust the timing of their movements to avoid attracting the attention of visual or olfactory predators?
Do female ungulates select parturition sites, and do young select bedding grounds where olfactory predators would have a hard time finding them?
Do Nest Site Characteristics Influence Nest Predation Rates by Olfactory Predators?
Impact of avian mass, surface area, and metabolic rates on olfactory predators
Impact of nest characteristics on olfactory predators
Do Weather, Convection, Isolated Surface Features, or Shelterbelts Influence Nest Predation Rates of Olfactory Predators?
Impact of weather on olfactory predators
Impact of convection on olfactory predators
Impact of isolated surface features on olfactory predators
Impact of shelterbelts on olfactory predators
Do Prairies, Savannas, Forests, or Edge Habitats Influence Nest Predation Rates of Olfactory Predators?
Nest predation by olfactory predators in prairies and open fields
Nest predation by olfactory predators in savannas
Nest predation by olfactory predators within forests
Impact of edge habitat on olfactory predators
Using the Physics of Airflow to Redefine Common Ecological Terms
Examples from forest ecology of the confusion that can be created by ambiguous definitions
What is a forest patch or habitat patch?
What is a forest interior?
What is a forest edge?
How far does a forest edge extend into a forest?
What is a forest clearing?
Benefits of defining ecological terms based on the physics of airflow
Dangers posed by depositional odor trails
Dangers posed by odor plumes
Can the olfactory-concealment theory help guide future research and provide answers to questions that heretofore have lacked explanation?
Does the olfactory-concealment theory have any applied value? References Appendix 1 Latin Names of Species Mentioned in this Book Appendix 2 Symbols Used in this Book Appendix 3 Forces Controlling Wind Speed and Direction Appendix 4 Pasquill’s System for Measuring Atmospheric Stability Index