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

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