Social Stress

Question 1

What causes social stress in the natural environment?

Answer 1

Competition for resources

Question 2

What causes social stress in captivity? How may these be divided into groups?

Answer 2

• Physical or Pychological
  Unsuitable housing/husbandry
  Inappropriate group composition (aggression)
  Inappropriate density (crowding/isolation)
  Frequent exposure to unfamiliar individuals (breaking social bonds/lack of control-> anxiety)
  Poorly developed social skills (abrupt weaning)

Question 3

What are the behavioural effects of social stress?

Answer 3

• v social interaction
• v reproductive behaviour
• v exploration
• ^ submissive/defensive behaviour
• ^ anxiety

Question 4

What are the physiological effects of social stress?

Answer 4

• ^ HPA activity
• ^ BP and HR
• v reproductive acitvity
• v body weight
• ^/v body temp
• immunosuppression
• pain inhibition (SIA)

Question 5

What do social dominance hierarchies require?

Answer 5

Individual recognition

Question 6

What types of hierarchy may exist?

Answer 6

> Linear or circular
Fluid (eg. hens when they go off lay move to bottom of pecking order) or static
- may be situation specific

Question 7

What is the purpose of hierarchies?

Answer 7

Minimised the need for aggression, ^predictability and stability of social relationships

Question 8

What is stress exposure governed by?

Answer 8

• rank

- type of social organisation

Question 9

In hierachies, what two types of stress levels is low rank associated with?

Answer 9

In many species, low rank = high stress
> “STRESSFUL SUBORDINATION”
In some species, low rank = low stress
> “NON-STRESSFULL SUBORDINATION”

Question 10

Give some animals which expiernce stressful subordination

Answer 10

Mouse eared lemur 
CAPTIVE wolves 
Pigs 
Rabbits
Babboons

Question 11

Outline the dominance hierarchy of a group of baboons

Answer 11

Stable hierachy, groups 50-150 
Will win 95% of fights with lower rank, and lose 95% with high ranks 
Maintained by psychological bluff (aggressive displays rather than aggressive attacks) and "displacement aggression" inflicted on ranks below 
> Subordinate individuals 
- less control/predictability 
- limited social support 
- fewer outlets for frustration 
=> STRESS

Question 12

Give an example where environmental stress provided a buffer for social stress

Answer 12

1984 - East African Drought

• ^ foraging
• maintained body mass
• v displacement targeting of subordinates by domainants
• > v GC in subordinates

Question 13

When may dominants in a stressful subordination population show signs of stress?

Answer 13

Instability in the group

• Key individual dies/joins
• Coalition partnership forms/breaks
• > ^ fighting, challenges, “coalition politics”
• > stress

Question 14

Give examples of animals where dominance is stressful

Answer 14

African Wild Dogs
Mongooses
RT lemurs

Question 15

Why may dominance be stressful in some species?

Answer 15

Constant reassertion of high rank through overt aggression
Dominancy frequently challenged
Dominance individuals = ^GC

Question 16

In which species are none of the members stressed?

Answer 16

Egalitarian society - No dominance hierarchy. Small groups of related co-operative breeders
Subordinates reproductively suppressed (“social contraception” by pheromones (relaxed waiting strategy rather than physical enforcement)
Subordinates help out older siblings

Question 17

Who compared social hierarchies and stress levels?

Answer 17

SAPOLSKY 2005

Question 18

What are the 5 factors for consideration in social stability?

Answer 18

> Firstly bear in mind fission (WILD) v fusion (CAPTIVE)
1. Age at formation - young and old easy to combine, adults harder
2. Familiarity and genetic relationship - familiarity often reduces hostility eg. inbred mice show reduced hostility but may increase competition as likely to value same things eg. dogs
3. Sex composition
eg. Male rats more stressed in same sex groups than individually
Female rats more stressed alone
- ethnologically males would only share territory with females and young, females would share with male, females and offspring
eg. captive primate groups housed in inappropriate group composition (mixed age/gender) experience abnormal aggression
eg. chimpanzees - risk of wounding more dependent on sex composition than size of group
eg. pig-tailed macaques - more aggression in female only groups than groups with a male
4. Environment
- complexity good
- stability necessary eg. cleaning cage out every day -> ^ aggression in mice
5. Group sizes and densities
- laying hens form dominance hierarchies in small groups and will attack unfamiliar birds, BUT in 100+ groups less aggression shown
- crowding can ^ aggression and v reproduction (farmed deer and lemmings)

Question 19

What should be considered when evaluating “crowding” of animals?

Answer 19

Is the human definition sufficient?

• usually based on body mass, not sex ratio etc.
• if cages kept close together may still be “crowded” with respect to olfaction

Question 20

Outline 2 case studies of social instability in commercial rearing

Answer 20

1. Pigs
   - naturally highly social, live in stable family groups, highly intolerant to strangers
   - commercially mixed at weaning, at beginning of grower/finisher period, within groups of gestating sows
   > aggression, resource displacement, suppressed immune response, v growth and reproduction
   - aggression at weaning not a direct distress response to weaning
   - if allowed to mix between farrowing crates v fighting and v fearfulness (though this ^disease risk)
2. Dairy cattle
   - natually cohabit in large herd, new members rarely accepted
   - commercially, calves separated from mothers and grouped with other, regrouped according to growth rate, heifers -> milking herd, regrouped according to milk yield, sale
   - consequences = aggressive interactions, distress, v feed intake and milk yield

Question 21

Why may some of the negative effects of social instability not be seen in modern breeds?

Answer 21

Been selected for high reproduction rates so not affected as much

Question 22

What does the mother-young social bond provide?

Answer 22

• affiliative behaviour eg. allogrooming
• nourishment
• warmth and protection
• information transmission (food/predators)

Question 23

Outline the social separation process of natural weaning.

Answer 23

Gradual v milk intake and ^ solid

Gradual ^ social independence from dam

Question 24

Why is early weaning carried out?

Answer 24

• Triggers return to cycling to ^ yield in dairy cows

- Maternal illness/death/lack of care

Question 25

What does early weaning cause?

Answer 25

• Disruption of social bond, termination of milk supply
• Exposire to social and physical stressors
  > distress vocalisation
  > v body mass/growth rate
  > altered sleep patterns
  > suspension of play
  > ^GC
  > altered HR/temp

Question 26

Outline 2 case studies of early weaning

Answer 26

1. Pigs
   - Naturally secluded sow and piglets for a week
   - < 5months spends gradually less time with them and integrates into group
   > commercially first month intensive interaction with piglets
   > week 4 abrupt weaning and mixing
2. Dairy cattle
   - Naturally milk transfer V after first few weeks, weaned at 6-9 months
   > commercially separated from cow within hours, bottle fed then weaned onto solid food
   > show distress response when separated from cow and weaned from milk
   > BUT ^ distress shown if left to form social bond before separation

Question 27

What is social buffering?

Answer 27

Conspecifics reduce stress associated with maternal separation in foals, piglets and calves
- v stress repsonse
- ^ recovery from distress
> familiarity and emotional status of partner affects effectiveness of social buffering eg. rat footshocks, experience v. naive partner

Question 28

How may coping with stressful events be affected by personality type? Give 4 examples.

Answer 28

1. Ability to form coalition partnerships - social buffering
2. Anxiety - Ability to differentiate threatening and neutral interactions (anxious individuals cannot differentiate!)
3. Rectivity - Reactive (high GC due to lack of control) v proactive.
4. Ability to distinguish win from loss - if can’t distinguish (“pessimist”) have ^GC