L14 - Foraging behaviour Flashcards
What are generalists foraging strategy?
Feed on a wide variety of food items. They may use opportunistic foraging strategies, exploiting whatever food sources are available in their environment, e.g. racoons, baboons
What are specialists foraging strategy?
Feed on specific types of food. More specialised foraging behaviours to locate and consume their preferred foods, e.g. koalas (eucalyptus leaves); pandas (bamboo)
Carnivores: what are hunters?
Predators, rely on keen sense such as sight, hearing, and smell to detect prey, and they may use various hunting strategies such as stalking, chasing, or ambushing. E.g. lions, wolves, and eagles.
Carnivores: what are ambush predators?
Use camouflage and stealth to ambush their prey. They wait until prey comes within striking distance before launching a surprise attack, e.g. crocodiles, some snakes
Herbivores: what are grazers?
Feed on grasses and other low-lying vegetation. Use selective feeding behaviours to choose the most nutritious plant species or plant parts, e.g. cows, springbok
Herbivores: what are browsing?
Feed on leaves, twigs, and shoots from trees and shrubs. Use their height advantage to reach higher branches or foilage, e.g. giraffes and elephants
What are scavengers?
Scavengers feed on dead and decaying organic matter. They may use their sense of smell to locate carrion or rely on visual cues such as circling scavenging birds to find food, e.g. vultures, hyenas
What are filter feeders?
Many aquatic animals, such as whales, baleen sharks, and some species of fish and invertebrates, are filter feeders. Passively collect plankton, small organisms, or organic debris from the water as it passes through
What are tool users?
Use tools (sticks, stones, or other objects) to extract or manipulate food items, e.g. chimpanzees use sticks to extract termites from their nests, some birds use twigs to extract insects from crevices.
Optimal foraging - bees?
Nectar-collecting bumble bees (Bombus impatiens) use efficient travel routes when foraging on familiar resources.
Optimal foraging - baboons?
Plan their foraging journey to out of sight resources. Fed on fruit more often than expected in the mornings. Fed on seeds often during their comparatively undirected and slow homebound journeys.
What is optimal foraging theory (OFT)?
OFT is a theoretical framework to understand animal foraging. Developed in the 1960s by ecologists such as Robert MacArthur and Eric Pianka
What are the basic assumptions of OFT?
For individuals to maximise fitness, they should adopt a foraging strategy that provides the most benefit (energy) for the lowest cost (time, effort) maximising the net energy gained. Natural selection has resulted in foraging behaviour that maximises fitness. This is the basic tenet of optimal foraging theory
OFT - What is energy maximisation?
Organisms seek to maximise the energy gained per unit of time spent foraging
OFT - What is Time minimisation?
Organisms seek to minimise the time spent foraging to allocate time for other activities.
OFT - What is Risk sensitivity?
Foragers take accounts the risks associated with different foraging options, such as predation risk or resource depletion
OFT - Optimal foraging models - What is marginal value theorem?
Predicts the optimal time to leave a resource patch based on diminishing returns.
OFT - Optimal foraging models - What is E and t an T - marginal value theorem?
E = the average rate of resource intake
t = time spent foraging within the current patch
T = travel time between patches
OFT - Optimal foraging models - What is diet choice models?
Predicts the optimal diet composition by considering the energy content and handling time of different prey items.
OFT - Optimal foraging models - diet choice models, what is E, h, E/h?
E = energy a prey item
h = time to consume the prey
E/h = profability
This is why you find chopped, peeled and prepared pineapple in your supermarket - same E, but lower h
OFT - Optimal foraging models - What is Patch use models?
Predicts how organisms should allocate their time between patches of resources to maximise their energy intake. E.g. mussel availability
OFT - why is it a waste of time?
Any theory based on optimisation is inappropriate for investigating behaviour, as animals should not be expected to behave optimally, and, anyway, it is not possible to test if they are behaving optimally.
OFT - why is it a waste of time, however?
If you take optimal foraging theory in the wider sense, acknowledging that an animal’s behaviour will depend in its state (energy levels, health, reproductive state), its enviro (e.g. predation risk), the foraging behaviour of others in the population (competing for the same food) and its future behaviour (i.e. actions cannot be considered in isolation), then then notion that behaviour maximises fitness can be used as a tool for generating testable hypotheses and predictions concerning how we expect animals to forage
OF assumptions, reality, solution? Individuals from the same species living in similar environments have the same diets/preferences?
Reality: individual foraging specialisation to reduce competition and increase energy acquired per unit time.
Solution: extend the framework to capture this specialisation
OF assumptions, reality, solution? Predators have perfect knowledge of their environment (energy content, travel time between patches, time to find and handle food etc)?
Reality: Predators need to learn about their environment to inform their foraging decisions. (Bayesian updating/learning, linear operator and relative payoff sum learning rules).
Solution: Extend the framework to capture this learning process
OF assumptions, reality, solution? Predators make prey choices in the absence of competition?
Reality: This is particularly true where animals live together in groups
Solution: extend the framework to capture social foraging.
What is Shared Ds, Despotic Dd, group optimal Dg?
More energy acquired and time spent = Ds
medium both = Dg
Lower both = Dd
