social behavior

Question 1

benefits of living in a group

Answer 1

1. ↑ access to food
2. ↓ vulnerable to predation
   
   • dilution effect: ↑ in # = ↓ in chances of being eaten
3. ↑ defense against predators
4. ↑ defense against common competitors
5. thermoregulation
6. maternal care

Question 2

costs of group living

Answer 2

1. ↑ competition for valuable resources (main reason)
2. ↑ parasite & disease exposure
3. ↑ conspicuousness

Question 3

social organization

Answer 3

hierarchies:
* linear: A>B>C (clear structure)
* triangular: A>B>C>A
* despotic: A>(B=C=D) ➞ rarer for domestic species/mammals
* dom will make themselves look larger, stronger, fiercer
* sub will show submissive B (mimicking youth; sub dogs/cats act young for food)

coordination
* time (synchronization) and/or space (cohesion): e.g. 4 sows nurse piglets same time and/or place
* leader-follower or collective-decision: e.g. waiting for signal or multiple sheep on pasture stay vigilant and all run together

Question 4

↑ access to diff better food

Answer 4

• benefit of living in a group

1. better food quality
   
   • get info on food quality from others’
     disgust responses & food aversion
     
     • humans have facial expressions, chx have gestures
     • ex: mouth spitting, bleh-ing, etc
     • observational learning in social groups: chx tasting experiment: observer alters behavior after seeing actor have an adverse response to food
2. bigger prey
   
   • ex: multiple prides can take down elephant, bull, etc.
   • ex: dogs in groups ➞ pheasant hunting
3. clumped seasonal sources

Question 5

↓ vulnerable to predation

Answer 5

• benefit of living in a group
• more eyes = more defenders
• predator avoidance & detection through many eyes hypothesis
  
  • ex: sheep: 1 member stays vigilant for predators: head up using eyes & ears to evaluate risk ➞ benefits for health & safety
• dilution effect: chance of being caught/affected goes down in larger groups
  
  • ↑ group size = ↓ chance of being eaten
  • ↑ group size = ↑ amount of time indiv sheep spends eating

Question 6

↑ defense against mutual competitors

Answer 6

• benefit of living in a group
• ex: wild horses: polygynous mating system
  
  • compete w/ other males to maintain harem
  • 1 sub cannot outfight dom so group of sub males work together ➞ ↑ defense against dom & chances of mating

Question 7

thermoregulation

Answer 7

• benefit of living in a group
• org maintain stable body temp by balancing heat production & loss
• ex: swine unable to cool themselves by sweating
  
  • wallow in mud, find shade, drink water
  • cold: cluster & shiver ➞ lying close together can save energy
  • energy going towards keeping warm ➔ using body fat & muscle movement (shivering) to keep warm
  • producers loose money b/c:
    
    1. time spend not eating
    2. weight being used for energy

Question 8

↑ competition for valuable resources

Answer 8

• cost of group living: main reason against
• food, mates, nest sites, resources
• only get a slice of the pie: ↑ group size = ↓ slice
• distribution vs patchiness of resources: ↑ competition for patchy resources
• ex: feeding competition costs to social living in group-housed sows
  
  • maintaining dominance hierarchy through fighting leads to injury, death, & pregnancy loss
  • challenge: to learn social living in sows to maintain group housing for better envir ➞ welfare
  • sow pen experiment:
    
    • low-ranking sows with no partition (covering/protection) received highest amounts of aggression as opposed to those in fully or partially covered pens
    • covering bodies gives protection to lower-ranking sows
• covering bodies gives protection to lower-ranking sows

Question 9

↑ parasite & disease exposure

Answer 9

• cost of group living
• ↑ indiv in group = ↑ parasites
• social living ↑ parasite load
• ex: large colonies of prairie dogs have more fleas
• stocking rates: human controlled designation of social groups
• ex: chx with ↑ stocking rate showed largest # of parasite eggs

Question 10

↑ conspicuousness

Answer 10

• cost of group living
• large herds easier to spot by predators

Question 11

nearest neighbor

Answer 11

• way to measure proximity & sociality
• Social associations using distance criteria with direct and indirect connections
• Direct = animals are labeled as associating if they are next to each other
• Indirect = animals can also be said to associate using the chain rule: Animals A and C are associating because both are next to animal B
• gives little info ➞ no quality

Question 12

Sociality

Answer 12

how much animals in a group associate with each other and form cooperative societies
* methods of measuring sociality:
1. Proximity
2. Social network analysis
3. Social dominance analysis

Question 13

bunching behavior

Answer 13

benefits:
1. access shade ➞ thermoregulation
2. avoid insects ➞ ex: flies in cows eyes

Question 14

Social network analysis

Answer 14

• way of measuring sociality
• look at direct & indirect relationships in social groups
• the degree of sociality in a species depends on the # of indiv interacting
• sociogram:
  
  • animals = nodes
  • association to others = ties/edges
  • thickness = degree of association between animals
  • arrows = directionality (i.e. who is directing the behavior & who is receiving it

Question 15

Social dominance analysis

Answer 15

• way of measuring sociality
• maintaining dominance hierarchies through repeated competitions for food, resources, shelter, or mates