Optimal foraging theory and predator prey behaviour II

secondary defence behaviour: reduce success of attack
1. Stotting
  1. Thomsons Gazelle:-Likely to show in safer situations with less likelihood of predator catching them, in slow fights. Stating behaviour had been found to indicate to the predator it had been detected, but didn't deter or invite attack, So more likely a warning to others behaviour than a signal of strength, however found less likely to be killed if it stops on average than if not (Caro, 1986)
  2. Impala:- prancing by flinging themselves into the air as high as they can to deter predators from eating them , as they look like they may be too much work and create too much energy loss for the predator = impedes calorific calculation for the predator.
  3. Springbok:- leaps into the air to show how unprofitable it may be for predators to try to attack it. Although it makes them easier to spot, may have many adaptive functions:- warning others thus improving the survival rates of kin and offspring, and the stutters fitness, may enable group formation making single capture harder, creates confusion fr the predator when many shot, and deterrence.
  4. "showing off behaviours"
    1. Also an honest signal
2. Mobbing
  1. Makes it far more difficult for predator to catch group of prey, and may get hurt/disorientated while it occurs. (expending more searching effort)
  2. Gulls:- position of eggs in the colony dictates whether mobbing behaviour will occur, if dominant will be central and mobbing will occur, if subordinate on outer edge, mobbing far less likely to occur, attempting to preserve the strongest genes for the colony. (KruuK)
    1. Increases fitness of the individuals as they are more likely to increase the life of kin and offspring, improving fitness.
    2. Mobbing, like many behaviours will often occur as an adaptive genetic mutation in a population, that will spread to others if it is successful enough. However, coevolution of the predator species means that mobbing behaviour will never be perfect due to the developmental arms race that keeps adapting.
    3. California ground squirrels:- gather and mob rattlesnakes by their burrows, one kicks sand and may even attack it. Heat up their tails to warn the snake (infrared view) that they will attack. May also actively seek snake skins or carcass and rub the scent onto their tails to increase perceived danger to other snakes.
3. Distraction
  1. Can increase reproductive fitness of the animal through increasing chances of survival of offspring, however decreases chances of its own survival.
  2. Ringed Plover :- When predator in the vicinity, it will pretend that it has a broken wing and limp away from the nest, leading the predator away from the nest to save their offspring, but then quickly fly off when they are farther enough away from the nest to avoid being killed.
  3. Threadfin butterflyfish:- has a fake eye spot on it's tail that predators are more likely to attack than it's real eye which is camouflaged by it's black head. The fin will grow back very quickly and have little damage impact on the fish, allowing it to get away from the predator.
Primary defence mechanisms: reduce probability of attack
1. Mimicry
  1. Batesian and Mullerian mimicry:- B = dishonest signals, M = Honest signals.
  2. Monarch and Viceroy butterfly:- Monarch = poisonous and honest, Viceroy = non-toxic and dishonest, works to deter predators from both due to risk of being ill from eating it.
  3. Texan coral snake and milk snake: coral snake = poisonous and honest, milk = non-toxic and dishonest.
  4. Monarch butterflt: how being colourful, then eaten then vomited is adaptive? Indirect selection - dead individuals educate their predators to avoid their relatives and species, improving fitness of their possible offspring or kin.
  5. Also steal from completely different species e.g.. Tephritid fly: has the pattern of jumping spiders on its wings which it bats as if for attention, in fact look like the spiders movements, which wave their legs, deterring predators and other spiders.
2. Selfish herding and dilution affect
  1. Redshank:- takeoff and land in a group to reduce the chance of single birds being picked off, harder for predators to choose which to attack.(Crewel, 1994) Flocking reduced the probability of of being killed.
    1. An optimal group size for maximising foraging vs vigilance time was also found
  2. Zebras:- more dilution effect, black and white stripes create a confusing background when in large groups to predators, especially wild cats that see in greyscale. More difficult for them to pick out one individual bra out of a large number.
    1. Burger and Gochfeld, Brazilian butterflies:- gather together 'mud puddling' at river banks. Large groups particularly attract predators, however in a group of 1000 with 5 predators, there 1% chance of dying per day, compared with 10x higher in group of 100. Provides survival benefits in excess of foraging costs.
Group kin selection/altruism.
1. Musk Ox wil forom a protective circle around the young in the pack to protect them when predators threaten attack, (Buchanan, 2014) in the arctic, these ox when confronted by snow wolves will form this circle, and actively charge towards the wolves to fend them off and maim them, increasing their chances of death but also increasing their chances of reproductive success with the survival of their offspring if they kill the predators, also in prospect increasing their general lifespan.
2. Baffalo wil not only defend their territory when confronted, but will actively seek out lion packs in order to kill the lion cubs, improving their long term reproductive success if successful at killing the next generation of lions, albeit at their own peril at the time.

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Optimal foraging theory and predator prey behaviour II

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