Chapter 12 Flashcards
3 ways to reduce being found
- Blending into the environment
- Being quiet
- Choosing safe habitats
What is Cryptic/Camouflage
avoidance of predators by blending into their surrounding environment
Cryptic/Camouflage Can happen two ways…
behavioral changes or natural selection favoring different pigments or patterns of color
ie: Cephalopods” octopi, squid, etc do it behaviorally
Experiment about camouflage
Hanlon and colleagues realized lots of predation occurs on cephalopods at night since predators have such good night vision. Use a noninvasive light source to observe the nocturnal behavior of cuttlefish and to test if they used camouflage at night to high from predators.
Being Quiet
Remade-Healey examined sound suppression in gulf toadfish
Wondered if toadfish listen for sounds associated with dolphins foraging behavior and then reduce the sounds they produce
Captured toadfish and kept individual males in tanks. The males began to make the noise, and then they were exposed to three different dolphin foraging sounds.
Found no differences in call rate between males before exposure to experimental sounds. Males exposed to pop sounds (key foraging sounds in dolphins) reduced sounds by 50% during and after they were exposed. They eavesdrop on their predators to ensure they are safe.
–Hormonal Analysis: Showed higher levels of cortisols
Choosing Safe Habitats
Parrots were tested form the Amazon and Australia.
Found that there was an independent ancestral evolution where some were nesting in trees and some move to nesting in cavities.
Birds who nested in cavities have longer nesting periods
Birds do this to avoid predation especially of their young
When encountering predators
Frontal cortex of the brain regulates the effect of stressors in behavior and that area of the brain may alter neurological and endocrinological responses to stressors such as predators
Smith and team exposed mice to two different stressors
- Odor of predator
- Immobilized in a device called a Universal Mouse Restrainer
Both predator groups increased the circulation of acetylcholine, serotonin and dopamine within the frontal cortex
5 Anti-predator encounter behaviors?
- Fleeing
- Approaching as predator to obtain information
- Feigning death
- Signaling to the predator
- Fighting back
Flight initiation distance
how close a predator can approach before prey flee
The farther an animal is from their home the sooner they flee from a predator
Animals who are mating/ foraging/ fighting were slower to flee from predators
Animals that had armor reduce preys prediction of risk
Animals who have experience with predator flee at greater distance
Treefrog Embros and Snakes
Treefrogs attach eggs to various vegetation and when the eggs hatch, the tadpoles drop into the water. If predation is weak, the egg season is longer.
When unbothered eggs hatched at 6 days.
If there is predation the vibrations of the snake causes the tadpoles to hatch at 4-5 days and swim away
Approaching Predators
Allows individuals to gather information about predators and reduces their chances of mortality
The Costs and Benefits of Thomson’s Gazelles Approaching a Predator
4 main predators: lions, cheetahs, hyenas, and wild dogs
Rarley approach hyenas and wild dogs because they cannot out run them.
3 Possibilities of benefits:
1. Decreases the risk of predation
- Allows gaelles to gather info about a potential threat
- Serves to warn other groups members of the potential danger associated with predator
Cheetahs respond to this by giving up because the element of surprise is gone
Feigning Death
Occurs when an individual falls down and remains frozen (tonic immobility)
Ohno and Miyatake
Adzuki bean beetle will either fly away or fake death
Hypothesis: there is negative correlation between the intensity of death faking the the ability to fly – those who do one more over the other will be better at it
For faking death: exposed beetles to danger and measured how long they froze
For flying: dropped a beetle through a hale and measure whether they dropped or flew and how far it flew.
Signaling to Predators:
Warning Coloration in Monarch Butterflies
Milkweed food contains chemical called cardiac glycosides, which are toxic to birds and are stored In the butterflies. When a bird eats the monarch, the toxins make the predator ill.
Signaling to Predators:
Tail Flagging As A Signal
Communicates to predator that an attack is unlikely to be successful
Fighting Back:
Chemical defenses in beetles
defend themselves against predators by using a spray that’s acidic.
Mobbing
a group of prey join together approach a predator and try to chase it away
Fighting Back:
Social Learning and Mobbing in Blackbirds
Experiment: a model and a naive bird in each location. The design was that each bird could see another bird and this bird acted as a predator.
Then there was another bird, which was the real predator. The naive bird could only see the fake predator, and the experienced bird only saw the real predator.
Found that the naive bird mobbed the fake predator after seeing the experienced bird mob. → Cultural transmission allows these birds to figure out which predators to mob
Predator and Foraging Trade-offs
Animals that spend time engaged in anti-predator behavior could have been foraging, mating, resting, playing
Predator and Foraging Trade-offs Experiment
Lima and Valone: Foraging/Predation in Squirrels:
Alter foraging choice as a result of predation from red tailed hawks.
Eat food where they found them or carry the food to a safer area. The closer the refuge from the predation, the more likely squirrels were to use the shelter when foraging.
Presented 2 types of food: a large cookie and a small cookie. (Used instead of nuts cause they tend to hide the nuts and not eat them.
2 critical pieces of information: the profitability of small food items needed to be greater than large food items – in the absence of predation, squirrels would take smaller food items.
The total handling time with larger food was great enough that optimal foraging models predicted that larger items were eaten in cover.
Hypothesis: when faced with predation, squirrels would find larger food items to bring back to cover ← this was the results
