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動物行為學 (通識)
國立臺南大學 通識課程 2011年春
07 對抗掠食行為
(Antipredator Behavior)
鄭先祐 (Ayo) 教授
國立台南大學 環境與生態學院
生態科學與技術學系
環境生態研究所 + 生態旅遊研究所
Ayo NUTN Web: http://myweb.nutn.edu.tw/~hycheng/
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Ayo 2011 動物行為學 (通識)
Antipredator behavior
 Avoiding predators
 Blending into the environment
 Being quiet
 Choosing safe habitats
 What to do when prey encounter predators
 Fleeing, approaching predators,
 feigning death, signaling to predators
 Fighting back
 Predation and foraging trade-offs
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Snake and ground squirrels
 Approximately a million years.
 Strongly selected for ground squirrels to be able
to identify their predators and to respond to them
with fine-tuned behaviors.
 Squirrel antipredator behavior includes throwing
dirt, pebbles, and roots at putative predators, as well as
emitting alarm calls that are specifically made when
snakes, but not other predators, are present. and also
immunological defenses.
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Ground squirrel pups
emerge from their
burrows at about
forty days. Shortly
before this, there is
an increase in their
immunological
defenses against
snakes.
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Ground squirrel pups often face serious predation threat
on their first emergence from their burrow.
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Avoiding predators
 Blending into the environment
 Cryptic, hidden through camouflaging, making their
detection by predators unlikely.
 範例：Cuttlefish (烏賊) camouflaging
 (A) using uniform color to camouflage itself against
the rocks
 (B) using a “mottled (斑駁的) ” camouflage pattern,
with small dark splotches resembling the dark patches or
rocks and sand
 (C) a “disruptive(破裂的)” camouflage pattern
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Uniform color to camouflage
Mottled camouflage pattern
Disruptive camouflage pattern
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Being quiet
 Gulf toadfish (prey)and bottlenose dolphins (predator)
 Dolphins orient toward the “boatwhistle” sound produced by
male toadfish during breeding season.
 Dolphins produce two kinds of sounds, high-frequency
whistle for social communication, low-frequency “pops” for
foraging.
 Gulf toadfish become silent.
 Playback test
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Wax moth and bat
 Subtle differences between male moth sounds and bat
echolocating sounds.
 Females were indeed able to distinguish between these
types of calls and responded appropriately.
 (playback test)
 Fanning their wings when they heard male calls
 But dramatically decreasing this behavior when they
heard bat echolocation calls.
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Choosing safe habits
 Predation and choice of nesting sites in parrots
 Phylogenies examination showed the ancestral state was
tree cavity nesting.
 Why the nesting in other cavities had evolved
independently many time in both Australian and
Amazonian parrot species?
 Whether predation was the key selecting for the shift
away from tree cavity nesting?
 The data on both Amazonian and Australian parrot species do.
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encounter with a predator.
A scavenging skua gull descends from the air in search of
penguin eggs or unattended chicks, while these two gentoo
penguins attempt to fend it off.
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What to do when prey encounter predators?
1.
2.
3.
4.
5.
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Fleeing
Approaching predators
Feigning death
Signaling to predators
Fighting back
Ayo 2011 Ethology (通識)
Fleeing
 The most common response of prey that have spotted a
predator is to flee for safety.
 Flight initiation distance, how close a predator can
approach before prey flee.
 Gathered published data from 61 studies of flight
initiation in mammals, fish, birds, and reptiles. (metaanalysis)
 Animals far from of their refuge initiated fleeing from a
predator sooner than animals closer to their refuge.
 Animals involved in foraging, mating, or fighting were slower
to flee from predators than animals were not currently involved
in such behaviors
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predators that
feed on treefrog
eggs
(A) here a wasp
forages on
treefrog eggs
(B) Snakes are
another
dangerous
predator on redeyed treefrog
eggs.
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Ayo 2011 Ethology (通識)
Treefrogs respond
to wasp predation
by hatching early.
Green bar represent
hatching rate of
clutches that
suffered wasp
predation, while
orange bars indicate
undisturbed
clutches.
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five days old
six days old
undisturbed by predation
Treefrogs also
respond to snake
predation by
hatching earlier
than normal.
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Proximate cues?
 Vibrational cues associated with snake attacks as the
proximate cue for when to switch from terrestrial
habitats to aquatic ones.
 To test the hypothesis, using three kinds of sounds
(playback test)
 Two kinds of the vibrations associated with snake attacks and
One kind of rainfall
 The cues associated with snakes resulted in treefrogs that
hatched earlier.
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Snake attack and eats
an entire clutch of eggs
A rainstorm
Snake eats one or two eggs
in s short series of bites
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Approaching predators
 This approach behavior allows prey to gather important
information about putative predators and hence reduces their
chances of mortality.
 Approach behavior is often undertaken by healthy adults.
 This type of behavior has been extensively documented in
vertebrates, particularly in fish, birds, and mammals.
 Prey typically approach a potential predator from a distance in
a tentative(嘗試的), jerky(急動的) manner.
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案例：Gazelle antipredator behavior.
(A) Gazelles are constantly vigilant (警戒的) for
potential predators
(B) many different species, including the cheetah
hunt gazelles.
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(A) the probability of approach behavior
occurring in gazelles is a function of group
size, as indicated by the logistic curve.
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(B) cheetahs respond to gazelle approach behavior. The
distance a cheetah move away in response to gazelle
approach behavior is also a function of the gazelles’
group size.
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Inter-populational differences in
approach behavior in minnows
 Two different populations of minnows (from the Dorset
area and Gwynedd area)
 Dorset population is under strong predation pressure from
pike predators
 While pike are absent from the Gwynedd population of
minnows
 Both populations of minnows increased their group size
when faced with predators in the laboratory, but the
Dorset population tended to maintain larger
groups.
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(A) Dorset minnow
respond to predators
by decreasing their
predator inspection
behavior
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(B) No statistically significant decrease in inspections
occurs in the Gwynedd minnow population.
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Feigning death
 Faking, or feigning, death is an antipredator behavior
seen across a spectrum of species.
 Adzuki bean beetle
 Either fly away or feign death
 Hypothesized that a negative genetic correlation existed
between the intensity of death feigning and the ability to fly
 Artificial selection, longer duration of feign death vs.
shortest duration of feign death
 After 8 generations
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The long duration lines are in green and the
short duration lines are in orange.
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Signaling to predators
 Warning coloration in monarch butterflies
 Monarch butterflies ingest milkweed plants, which
contain chemicals called cardiac glycosides.
 These chemicals, which are toxic to birds, do not
harm the monarchs.
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When a naïve predator eats a monarch, the toxins in the
butterfly make the predator violently ill- temporarily .
The color patterns of monarchs act as warning coloration for
that predator who now avoids feeding upon monarchs.
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Tail flagging as a signal
 Some animals send signals that may serve to notify a predator
that is has been spotted.
 When the predator is an ambush hunter that relies on
surprise, such a signal often cause it to move on the leave the
area, and hence clearly benefits the prey.
 Tail raising event in White-tailed deer.
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Fighting back
 Chemical defense in beetles
 bombardier defense. When the bombardier beetle is
threatened, it releases chemicals that ward off predators.
 This bombardier beetle is being attacked from the front, and so
it is directing its chemical spray forward.
 They fire the spray backward, when attacked from the rear.
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Ayo 2011 Ethology (通識)
Social learning and mobbing in
blackbirds
 Blackbirds undertake a form of attack called predator
mobbing.
 Once a flock of blackbirds spots a predator, they join together,
fly toward the danger, and aggressively attempt to chase it away.
 Such group attacks often work well enough to force predators
to leave the blackbirds’ area.
 Mobbing is a form of cultural transmission.
 Animals Raised in captivity failed to have mobbing behavior.
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foraging-predation trade-off.
When animals are being vigilant for predators, it is often
at the cost of other activities. The starlings here can’t be
foraging for insects while they scan the sky of hawks.
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Predation and foraging trade-offs
 Squirrels alter their foraging choices as a result of predation
pressure from redtailed hawks.
 Squirrels who could either eat their food items where they
found such items or carry the food to cover were more likely to
carry items to an area of safe cover, particularly as the distance
to safe cover decreased.
 The closer the refuge from predation, the more likely they
would use such a shelter when foraging.
 Squirrels were much more likely to carry larger items to safe
areas before continuing to forage.
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(A)Here a squirrel is foraging at a feeding station
(B) A squirrel heads for cover with a food item (a part of
a cookie) in its mouth.
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動物行為學 (通識)
問題與討論
國立臺南大學 通識課程 2011年春
Ayo NUTN website:
http://myweb.nutn.edu.tw/~hycheng/
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Ayo 2011 動物行為學 (通識)