Download Migration and orientation

Migration and orientation
Migration and orientation
• Migration is the periodic, two-way travel of groups of animals from one location
to another
• Orientation is the ability to follow a bearing (i.e., which way is north?)
• Navigation is the ability to adjust a bearing and follow it (i.e., how do I get to
where I want to go, knowing that that way is north?)
Bobolinks have changed their migration by adding a new segment
Orientation cues
• Stars
Orientation cues
• Magnetic fields
Orientation cues
• Smell
Orientation cues
• Sun
 Honeybees use internal clock mechanism to compensate for sun’s
movement
Optimal Foraging
Resource allocation
Tradeoffs
• Foraging is tradeoff with other functions
 Survival
 Predator avoidance
 Mate search
 Territory defense
 Offspring care
Optimal foraging
• Efficient foragers use time/energy saved in foraging for other life history tasks,
which leads to higher fitness
• Natural selection will favor organisms that exhibit behavior that leads to
efficient foraging
Resource budgets change
• Rock Pipits Anthus spinoletta
• Mild Winter versus Harsh Winter
• Feeding: 6.5 hours vs. 8.25 hours
• Resting: 1.75 hours vs. 0.6 hours
• Fighting: 0.75 hours vs. 0.1 hour
Foraging success
• Benefits of foraging must be greater than costs of foraging
• Organisms will maximize the difference between benefits and costs
Costs & benefits
• Benefits
 Energy
 Nutrients
• Costs - usually measured as handling or foraging times
 Time
 Energy
 Predation risks
Foraging decisions
• Which prey to eat? (diet choice)
• Which individuals to pursue and eat? (prey size/quality)
• How many prey to eat?
• How long to forage?
• When and where to forage next?
Optimal foraging theory:
“decision rules”
• Prefer the more profitable prey
• Feed more selectively when profitable prey are abundant
• Include less profitable prey in the diet when most profitable prey are
relatively scarce
• Ignore unprofitable items regardless of their abundance
Do foragers make choices?
Crows and mollusks
Predation affects foraging
Marginal value theorem
• Food is found in patchy distribution
• The marginal value theorom predicts foraging behavior given patch quality,
and distance between patches
Marginal value theorem
Travel time
Patch quality
Communication, Courtship and Reproduction
Animal communication
• Why communicate?
 Courtship
 Foraging
 Alarm calls
 Language
Communication signals
• Signals that trigger behaviors in other individuals
• Will evolve only if they benefit both signaler and receiver
Communication
• Communication can play a key role in behaviors
 Among members of the same species
 Between species
• Successful reproduction depends on appropriate signals and responses
 Stimulus-response chain: behavior of one individual releases a behavior by
another individual
Visual displays
• Important in courtship and in aggression
• Baring of teeth by baboon communicates threat
• Flashing of fireflies attracts mates
Courtship displays
Bioluminescent displays of lampyrid beetles are species-specific
Using food to attract female
Pheromones
• Pheromones are long distance communication technique
Pheromones
• Chemical signals that diffuse through air or water
• May bring about behavioral change in receiver or cause physiological change
(priming pheromones)
Acoustical signals
• Sounds used to attract mates, secure territory, warn off rivals
• May also be used to communicate danger, keep groups together
Tactile display
• Signaler and receiver communicate by touch
• Honeybee dance
Illegitimate signals
• An illegitimate receiver intercepts a signal meant for individuals of another
species
 Termite smells pheromone of invading ant and attacks it
• An illegitimate signaler mimics signals
 Predatory fireflies mimic females of prey species
Communication facilitates group living
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Guards: set off an alarm call so group can seek shelter
Social insects produce pheromones that trigger attack behavior
Ants deposit trail pheromones between nest and food source
• Vervet monkeys give three specific alarm calls, depending on threat detected
Vervet monkey alarm calls
• In response to the snake warning call, the troupe of vervets will all stand up on
their hind legs in the open and look around on the ground
• In response to the leopard warning call, the members of the troupe run up to
the top of the nearest tree
• In response to the eagle warning call, the members of the troupe run into a
nearby bush
Communication
• Signals vary in their degree of specificity
• Level of specificity: relates to the function of a signal
 Mark territories with pheromones
 Species and other species specific
• Pursuit-deterrent signals: predator has been seen and should not waste time
chasing the prey