Feeding, Foraging, and Anti-Predator Behaviours

Generalists

Definition: Species with broad niches that exploit many food types; highly adaptable.
Example: Foxes thriving in urban/anthropogenic environments.

Specialists

Definition: Species restricted to very narrow diets; poorly adaptable to change.
Example: Pandas eating only bamboo despite inefficient herbivore gut.

Selectors

Definition: Feeding strategy focused on nutritionally rich parts of food.
Example: Humans mixing diet for vitamins, minerals, and proteins.

Bulk Feeders

Definition: Species feeding on large volumes of low-quality food.
Example: Elephants consuming huge quantities due to low digestive extraction efficiency.

Basal Metabolic Rate (BMR)

Definition: Minimum energy expenditure required to fuel cellular respiration.
Example: Hummingbirds have high BMR → constant high-energy feeding.

High BMR Strategy

Definition: Requires frequent, energy-dense intake and high physiological output.
Example: Hummingbirds with fast heart rate and endothermy.

Low BMR Strategy

Definition: Requires infrequent feeding, slow metabolism, often ectothermic.
Example: Crocodiles may feed once per year and thermoregulate using environment.

Regulators vs Conformers

Regulators: Maintain internal conditions via physiology/behaviour.
Conformers: Internal conditions follow environment.
Example: Humans regulate temperature; frogs conform and overwinter in pond mud.

Foraging Decision: What Should I Eat?

Definition: Foods chosen based on nutritional payoff and risk.
Example: Migratory birds selecting red berries due to evolved signal “eat me.”

Foraging Decision: What Should I Avoid?

Definition: Avoidance of items that induce sickness or reduce fitness.
Example: Horses avoid grazing near dung to reduce contamination risk.

Dietary Flexibility (Generalists vs Specialists)

Generalists: Track sickness cues + immunity from varied diet.
Specialists: Lack facultative behavioural flexibility.
Example: Specialists unable to adjust when food changes, risking malnutrition.

Optimal Prey Size & Risk Trade-Off

Definition: Animals balance energy gained with energy/risk cost of capture.
Example: Lions weigh prey choice (zebra = risky, gazelle = moderate, hare = low but insufficient).

Optimal Foraging Theory

Definition: Energy intake maximised when energy gained > energy expended in obtaining food.
Example: Predators choose slow, injured, or old prey to reduce cost.

Foraging Location Choice

Definition: Animals decide where to feed based on profitability and competition.
Example: Feeding away from group reduces competition but increases toxicity/predation uncertainty.

Social Information Use in Foraging

Definition: Individuals use cues from others to inform food decisions.
Example: Elephants eating mineralised sand after observing conspecifics alleviate stomach upset.

Foraging Summary Principle

Definition: Foraging behaviour varies to optimise energy gain vs time, risk, and social cost.
Example: Animals trade off rutting time vs feeding time during breeding seasons.

Primary Defences (Pre-Attack)

Definition: Strategies reducing probability of predator initiating attack.
Example: Camouflage in juvenile tits to remain inconspicuous.

Müllerian Mimicry (Honest Signal)

Definition: Two or more noxious species share warning signal.
Example: Monarch and viceroy butterflies both toxic to predators.

Batesian Mimicry (Dishonest Signal)

Definition: Harmless species imitates noxious species to deter predator.
Example: Milk snake mimicking the venomous coral snake.

Group Living: Dilution Effect

Definition: Individuals reduce personal predation risk by blending in.
Example: Penguins have countershading to reduce detection from above/below.

Group Living: Confusion Effect

Definition: Predator accuracy reduced by coordinated movement or disruptive patterns.
Example: Swarming fish or flocking birds impair predator targeting.

Group Living: Selfish Herd

Definition: Individuals reduce risk by placing others between themselves and predator.
Example: Prey moving toward centre of group during attack.

Group Living: Vigilance

Definition: Group members take turns scanning for predators.
Example: As group size increases, optimal ratio balances vigilance vs feeding time.

Secondary Defences (Post-Attack)

Definition: Strategies reducing likelihood predator captures or consumes prey.
Example: Wildebeest physically defending calves.

Fleeing as Defence

Definition: Evasion behaviour reducing capture likelihood.
Example: Gazelles outrunning predators.

Stotting / Alarm Signalling

Definition: Display signalling high fitness to discourage pursuit.
Example: Gazelles stotting to show endurance to predators.

Startle/Intimidation Display

Definition: Display making animal appear larger or dangerous.
Example: Komodo dragon inflating body and standing upright.

Distraction Tactics

Definition: Behaviour diverting predator away from vulnerable targets.
Example: Birds feigning injury to draw predator from nest.

Alarm Calls

Definition: Vocal signals warning group of predators; costly but informative.
Example: Prairie dogs emit alarm calls; group gains survival benefit.

Mobbing

Definition: Group collectively harasses predator to repel attack.
Example: Birds chasing away hawks or owls.

Predator–Prey Arms Race

Definition: Continuous coevolution where improvements in one select counter‐improvements in the other.
Example: Faster predators select for faster prey; faster prey select for stealthier predators.

Anti-Predation Summary Principle

Definition: Predation can be deterred pre-attack or disrupted post-attack; group success often greater than individual success.
Example: Group vigilance increases detection but reduces feeding time.