Lecture 5: Avoiding Predation Flashcards Preview

APS209 Animal Behaviour > Lecture 5: Avoiding Predation > Flashcards

Flashcards in Lecture 5: Avoiding Predation Deck (32):

what is an adaptation?

a heritable trait that enhances the fitness of it bearers
-through current benefits, or past benefits & evolutionary history


is every factor that reduces predation an adaption against predation?



current benefits of Mobbing: Kruuk 1964

-nesting gulls mob intruders
-risky behaviour for gulls
-prediction: if mobbing is behavioural adaption against egg predators, then mobbing should reduce egg predation
-experiment: hens egg every 10m, outside gull colony & into gull colony
-results: inside colony more likely crows will attack predation, predation reduces as you enter colony


when would you use the comparative method?

when an experiment can't be used
-way of comparing evolutionary hypothesis by comparing different taxa


e,g, of using a comparitive method: Mobbing

-two taxa (kittiwake - cliff gull, black headed gull - ground nesting gull)
-first gull = ground nesting
-kittiwake shouldn't use mobbing as not necessary
- to use comparative method you need good phylogeny
-if some cliff did mob and some ground didn't then prediction would be wrong


to use comparative method you need a strong

phylogeny method


antipredator adaptations 4 groups:



anti detection example

Crypsis, e.g. camouflage, transparency, nocturnally, subterranean living


anti Attack examples

-stotting in Springbok, selfish herding, mimicry and warning colouration


anti capture examples:

Vigilance, run, swim or fly fast, body part autotomy (tail loss in lizards)


anti-consumption adaptations

fighting back, feigning death, releasing noxious chemicals, being hard to swallow (e.g. inflation by puffer fish)


camouflage: Peppered moth

-makes peppered moth less detectable to predators
-2 subspecies; light form and melanic form
-larvae also camouflaged = dead twig


camouflage points to remember:

1) camouflage may involve any of the sense, not just vision
2) either (or both) prey / predator may be camouflaged


Testing whether camouflage words: Pietrewicz and Kamil

-trained captive blue-jays to respond to white underwing moths
-head up moths on pale bark hardest to detect!
Conclusions: behaviour of moths (where they settle) affects ability to detect them
--> so yea, it works


Behaviour & camouflage: Decorator crab

the crabs pile algae, sea anemones, coral on back to hide
-choosey about what species to decorate with, Dictyota menstrualis
- crabs without this species were 5 times more likely to be predated
-the alga contains a chemical that repels omnivorous fish


Stotting by Thomson's Gazelles

-stot when see predator
-jump up in air with legs down, signal to predators 'Ive seen you and I'm v fit and ready to flee'


Stotting by Thomson's Gazelles: "Ive seen you and am ready to flee" is known as the what hypothesis

Unprofitability hypothesis == the likely hypothesis


Stotting by Thomson's Gazelles: Anti ambush hypothesis

stating lets gazelles see what is ahead and reduces the chances they will be ambushed
--> but stotting occurs in all habitats including short grass


Stotting by Thomson's Gazelles: Alarm signal hypothesis

sotting warns conspecifics, especially offspring that predator is near
--> but even solitary animals Stot


Stotting by Thomson's Gazelles: Social cohesion hypothesis

stotting enables gazelles to form groups & flee in a coordinated manner
-but solitary animals stot


Stotting by Thomson's Gazelles: confusion effect hypothesis

-stotting confuses and distracts a predator preventing it focusing on one animal
-but solitary animals stot


Stotting by Thomson's Gazelles: is it an indicator of quality?

YES, lower proportion of stotters, than non stotters chased & predators fail to kill stotters
-honest signal of animals health


The selfish herd: Snake in pond where safest place for frog to sit

-frogs best close to other frog
-snake attacks then no individual target, selfish strategy
-benefits individual, but not group (if all sat together may make a bigger target bad for group)


selfish herd is an example of

Game theory


selfish herding affects ___ behaviour

-Bluegill sunfish prefer to nest in the centre of groups where they are safer from egg predators


selfish herding works through mechanisms known as

dilution effect
--larger the group, lower individuals chances of being eaten


selfish herding in Whirligig Beetles

-sits on surface on pond, eats small insects
-predated by fish that come up from below
-larger groups more attractive to predators
-BUT larger groups the predation rate for each individual is less


Whirligig beetles trade off :

-Food & predation risk
--food more abundant on outside of group but predation risk greater


Mayfly Emergence: Dilution effect (in time)

-nymphs = aquatic
-adults = aerial
predation risk is lower when many adults emerge as predators become satiated --> dilution effect, leading to synchrony of emergence


Similarity between: Gamete release in coral & Sea-bird egg laying

SYNCHRONY to benefit from dilution effect --> satiate predators preying on gametes/chicks


Group formation / vigilance

-Group formation may reduce predator attack/success via greater vigilance. If one individual in a group sees a predator it can warn the rest, or the others can see its escape behaviour.


Can grouping be costly?

--increased food competition
Sparrows; may feed alone/group
-"chirrup" calls signal to form a group
-predation risk = low = solitary
-predation risk = high = group