Feeding and Predators

Question 1

F: Food Groups

Answer 1

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))

Question 2

F: Conformity

Answer 2

• some species conform to prevailing environmental conditions
• some are regulators w/precise control over internal physiology (ie. brown bears and hibernation)

Question 3

F: Decisions

Answer 3

WHAT DO I EAT?
WHAT SHOULDN’T I EAT?
FOOD SIZE/INTAKE SIZE?
WHERE DO I FIND FOOD?

Question 4

F-D: What Do I Eat?

Answer 4

• 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

Question 5

F-D: What Do I Eat? (Example)

Answer 5

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

Question 6

F-D: What Shouldn’t I Eat?

Answer 6

• 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)

Question 7

F-D: What Size/Intake Size Food Be?

Answer 7

OPTIMAL FORAGING THEORY

• large = more energy BUT more cost/energy to find/process
• trade-off necessary: OPTIMUM = MAXIMUM ENERGY INTAKE/COST

Question 8

F-D: What Size/Intake Size Food Be? (Example)

Answer 8

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)

Question 9

F-D: Where Do I Find Food?

Answer 9

• 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)

Question 10

FORAGING: Summary

Answer 10

• 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

Question 11

H: Prey Defences

Answer 11

PRIMARY:
- reduce probability of attack
SECONDARY:
- reduce likelihood of successful attack

Question 12

H: Predator Inspection (Example)

Answer 12

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

Question 13

H-PD: Primary

Answer 13

• REMAIN HIDDEN/INCONSPICUOUS
• MIMICRY (aka. pretend to be dangerous)
• LIVE W/GROUP (aka. reduce selection odds)
• FIGHT BACK

Question 14

H-PD-P: Remain Hidden/Inconspicuous

Answer 14

• 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

Question 15

H-PD-P: Mimicry

Answer 15

• 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)

Question 16

H-PD-P: Mimicry (Evaluation)

Answer 16

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

Question 17

H-PD-P: Living w/Group

Answer 17

• 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

Question 18

H-PD-P: Fight Back

Answer 18

• 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)

Question 19

H-PD: Secondary

Answer 19

DISTRACTION
ALARM CALLS
MOBBING
SHOWING OFF

Question 20

H-PD-S: Mobbing

Answer 20

• can be dangerous; groups > solitary
• closeness = may be eaten
• unknown why individuals join mobbers in the first place

Question 21

H-PD-S: Showing Off

Answer 21

• 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

Question 22

PREDATION: Summary

Answer 22

• 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