Feeding and Predators Flashcards
F: Food Groups
GENERALISTS:
- often omnivores; bulk eaters; consume vast quantities of large types of food; QUANTITY; high BMR (basic metabolic rate) = regular demand (ie. foxes, elephants)
SPECIALISTS:
- evolved to only consume one/few specific types of food; alternative consumption can lead to health issues; QUALITY; low BMR = low energy demand (ie. pandas; giraffes (due to necks))
F: Conformity
- some species conform to prevailing environmental conditions
- some are regulators w/precise control over internal physiology (ie. brown bears and hibernation)
F: Decisions
WHAT DO I EAT?
WHAT SHOULDN’T I EAT?
FOOD SIZE/INTAKE SIZE?
WHERE DO I FIND FOOD?
F-D: What Do I Eat?
- red/black (common) are highly conspicuous but NOT NECESSARILY nutritional
- rare colours (ie. yellow) indicate nutritional value (ie. tannins/proteins/carbohydrates)
- BILLING & SHERMAN (1998); found less inhibited bacteria in lemons/ginger/nutmeg than common plants like onion/garlic
F-D: What Do I Eat? (Example)
CUES FROM PEERS:
- alone, a capuchin monkey is least likely to try novel food
- w/ group eating familiar food, monkey is moderately likely to try novel food
- w/ group eating novel food, monkey is highly likely to also eat novel food
F-D: What Shouldn’t I Eat?
- GARCIA et al (2014); animals avoid foods inducing sickness
- generalists pay more attention to sickness cues as encounter many various food types; specialists have no facultative response
- (ie. bat roots are info centres; communication of “bad food” travels quickly)
F-D: What Size/Intake Size Food Be?
OPTIMAL FORAGING THEORY
- large = more energy BUT more cost/energy to find/process
- trade-off necessary: OPTIMUM = MAXIMUM ENERGY INTAKE/COST
F-D: What Size/Intake Size Food Be? (Example)
CRABS & MUSSELS:
- crabs hunt medium mussels for optimum profitability w/o wasting energy on bigger ones
CHEETAHS
- a cheetah can either eat hare or search for gazelle; it should eat hare if:
H-PROFIT > (G-PROFIT - G-SEARCH ENERGY)
F-D: Where Do I Find Food?
- at most profitable habitat
- wherever others are feeding/not feeding (might be missing highly nutritional/rare finds)
- is there a local info centre (ie. bat roots)
FORAGING: Summary
- individuals vary foraging beh to optimise energy intake; energy gain is traded depending on costs lost in time/energy
- decisions are internal/based on peers’ actions, for ones own/social group’s benefit
- may trade-off costs of being w/others against the good of the group
H: Prey Defences
PRIMARY:
- reduce probability of attack
SECONDARY:
- reduce likelihood of successful attack
H: Predator Inspection (Example)
FITZGIBBON (1994):
STALKERS: (ie. cheetahs/lions); when detected, gazelles (more likely immature) often approached in less risky event (aka. when group large/low veg/cheetahs came close); inspections in small groups
- caused cheetahs to move more between rests/hunts (waste energy); prob of young gazelles being killed upon inspection higher than adults
- stalkers move away, enabling prey to monitor them; opportunity for young to learn survival against predators
COURSERS: (ie. wild dogs/hyenas); gazelles never approach
H-PD: Primary
- REMAIN HIDDEN/INCONSPICUOUS
- MIMICRY (aka. pretend to be dangerous)
- LIVE W/GROUP (aka. reduce selection odds)
- FIGHT BACK
H-PD-P: Remain Hidden/Inconspicuous
- often trade-off required again
- IE. great tits can be cryptic/obvious (aka. yellow/red bellied); cryptic tits blend in more so less are hunted BUT obvious tits are easier spotted and so easier to rescue/maintain
H-PD-P: Mimicry
- confusing the predator
- MULLERIAN (Muller (1807)); honest signal (aka. I look like this poisonous species because I too am poisonous)
- BATESIAN (Bates (1892)); dishonest signal (aka. I’m not really poisonous but I look it)
H-PD-P: Mimicry (Evaluation)
MULLERIAN:
- cost of conspicuousness VS dilution benefits (predation prob decreased)
- success depends on number of poison species in predator’s range
BATESIAN:
- cost of conspicuousness VS benefits of SUPPOSEDLY being poisonous
- success depends on proportion of poison species to “imposters” in predator’s range
H-PD-P: Living w/Group
- join optimum size groups to maximise “ideal” investment
- benefits include:
DILUTION: ie. penguins hunted by leopard seals dilute within the huge groups they stay in
CONFUSION: ie. red-shanks flock to lessen probability of being chosen by predator; preds preferred bigger groups, but smaller were more successful; big groups unlikely to fly upon seeing pred
SELFISH HERDING: ie. putting weaker members between yourself and preds
VIGILANCE: ie. redshanks; balance foraging time w/vigilance; medium group size to optimise profit
H-PD-P: Fight Back
- female wildebeest that defend young from attacks have higher lifetime reproductive success
- attackers can be worn down to pick on weaker member of group (ie. outrunning stalker cheetah)
H-PD: Secondary
DISTRACTION
ALARM CALLS
MOBBING
SHOWING OFF
H-PD-S: Mobbing
- can be dangerous; groups > solitary
- closeness = may be eaten
- unknown why individuals join mobbers in the first place
H-PD-S: Showing Off
- ie. stotting in gazelles; only makes cheetahs aware they’ve been detected, but doesn’t encourage/deter them from the hunt
- mothers who’s young escape are prone to this; those who’s young didn’t not so much
- HOWEVER, stotting reduces chance of successful hunt; even if it continues, it is either abandoned or fails as predators are too confused by stott to go on
PREDATION: Summary
- can be deterred/disrupted
- individuals show morphological/behavioural adaptations to reduce predation chance
- beh typically works better to deter predation in groups, though it can bring additional costs/issues
