Adapting To Arctic Weather And Preparing For Migration

Question 1

What is a stress response?

Answer 1

The body’s adaptations to correct a disruption of physiological balance

Question 2

What are the long term and short term responses?

Answer 2

1. Fight or flight: adrenaline- short term

2. General adaptation syndrome: glucocorticoids- long term

Question 3

What are the processes of the adrenal axis (HPA axis)?

Answer 3

1. Brain
2. Hypothalamus: CRF released into a specialised neural network to take it to pituitary gland
3. Pituitary: stimulated by CRF to produce hormone ACTH which circulates in the blood
4. Blood: ACTH binds to the adrenal cortex
5. Adrenal cortex: cells are stimulated to produce glucocorticoids

Question 4

What are the short term effects of glucocorticoids in animals?

Answer 4

Suppression of reproductive behaviour without affective reproductive system
Altered immune function
Increased gluconeogenesis
Increased foraging behaviour
Promotion of escape behaviour during the day
Promotion of night restfulness

Question 5

What are the long term effects of glucocorticoids in animals?

Answer 5

Inhibition of the reproductive system 
Immune suppression 
Loss of protein from skeletal muscle 
Accelerated neuronal degeneration 
Suppression of growth

Question 6

Describe the ‘capture, handling and restraint’ method to determine stress responsiveness in wild birds:

Answer 6

1. Take blood sample within 2 mins of capture
2. Birds subjected to standardised stressor (drawstring bag)
3. Take further samples at defined intervals

Question 7

What is the most efficient store of energy for migratory birds flying long distances?

Answer 7

Energy in the form of lipids (fats)

Question 8

Why are lipids good energy stores?

Answer 8

They have a higher energy density and have little water associated with them

Can store a lot of energy in a small space

Question 9

What is the highest percentage of fat found in a migratory bird?

Answer 9

50%

Ruby throated hummingbird

Question 10

What is spring migratory fattening induced by?

Answer 10

Photoperiod- long days

Question 11

Give an example of natural fasting in animals

Answer 11

When hens are incubating their eggs they lose interest in food to spend more time sitting on the eggs

Question 12

What are the two effects of corticosterone?

Answer 12

1. Basal (non stressed) concentrations regulate food intake and fat deposition
2. Stress induced corticosterone secretion is associated with activating the emergency life history stage