Different anti-predator strategiesIndividual

Make yourself unpalatable/toxicAposematismFeign death

Startle predatorMimic a predatorEvolve large size

SocialMutual defense

Improved vigilanceConfusion effect

Dilution effect

Monarch butterflies have aposematic coloration,

bitter taste, and heart poisons in their body that

are toxic to most vertebrates

Naïve bluejay eating a monarch butterfly

Same bluejayreacting to ingested

monarch

Same bluejay barfingseveral minutes later

Many predators have an innate avoidance response to aposematically colored prey items

Wooden snake models were used to test feeding responses

of naïve, hand-rearedMotmots (a type of bird)

Note that the motmotsavoided the models that most

resemble a coral snake

The numbers indicate how many pecks were delivered to each part of the “snake”

Many insect have toxic sprays or exudates that are

exceedingly noxious to predators

Bombadier beetles can direct their caustic spray in any direction

Some snakes and rodents can feign death quite convincingly

Prey species can often startle predators by suddenly appearing like a predator

Mexican vinesnake

Sphingidcaterpillar

Prey mimics predator

Front view of a zebra jumping

spider

Posterior view of a snowberry fly

The wing banding pattern, and associated wing movements of the strawberry fly display, appears to make this fly look like an aggressive jumping spider, and causes many jumping spiders to flee

Large size has its advantages

Packs of wolves are often unsuccessful at capturing

large mammalian prey

Sociality can be viewed as an anti-predator defense, particularlywhen young are threatened

e.g., mutual defense of young againstpredators by musk-oxen in a circular formation

Improved vigilanceThe larger the flock of wood pigeons, the

sooner it detected an approaching goshawk (as indicated by reaction distance)

The larger the flock of wood pigeons, the more difficulty goshawks

encountered in their stealth attacks

How can youexplain this

result?

Response of a flock of European starlings to an approaching peregrine falcon

Before After

What is the functional significance of this flocking response?How might it benefit an individual?What is the selfish herd hypothesis?

Cuttlefish Squid Pike Perch

Hunting success as measured by capture/contact ratio for 4 predators as a function of school size

Contact involved any discovery of a prey by a predator prepared to huntHunting success decreased with school size, presumably owing to confusion effect

Diagrammatic representation of twotypes of oddity

Odd prey contrast to group members plus background

Odd prey contrast to group members only

When predators attack a flock of birds or schools of fish, they to focus on the odd individuals, presumably because this helps them

overcome the confusion effectHow might this attribute of predators influence the evolution of coloration

patterns in prey?

Dilution effect in penguins

Young birds time their departure from the nesting colony to coincide with that of

many other fledgling guillemots (a type of penguin). Even though the parents (large

bird) accompany their young, only those youngsters that fledge at the peak

departure time are likely to survive the waiting predators.

Adelie penguins have to cope with formidable predators like this leopard seal, which attack penguins (particularly young

and vulnerable ones) as they enter the water

Dilution effect in mayflies

The more female mayflies emerging on a June evening, the less likely any one mayfly is

to be taken by a predator.