Habitats & Territories

Question 1

Three suitable habitats

Answer 1

• regular passive dispersal = high risk of loss, so viable in small species with huge productivity
• accidental = birds being blown over to other islands/countries
• active choice = orientation along gradients of light, scent, moisture, salinity, current

Question 2

Define ideal free distribution model

Answer 2

• choose habitats that maximise survival and reproduction AND free to enter any habitat

Question 3

Assumptions of IFD

Answer 3

1. Individuals try to Max. Fitness when settling in a habitat
2. Habitat locations differ in resources
3. Fitness of individuals decreases with increasing density due to increased competition
4. Individuals have equal competitive ability and can accurately access fitness payoffs of habitats
5. Individuals are free to move between habitats with no cost

Question 4

Define home range

Answer 4

Areas of repeated use that are undefended

Question 5

Define territories

Answer 5

• areas of exclusive use which is actively defended

- size of territory depends on the costs and benefits of excluding others

Question 6

Limits to territory defence

Answer 6

• lower threshold = does extra food exceed costs of defence
• upper threshold = if too many intruders, raises cost of defence
  = larger territory attracts more intruders, best to keep at smallest economic size
  = if resource is too abundant, owner can’t use additional benefits
  = rate of intake limited by handling time