1 How does an animal choose where to live?

2 5/29/08: Habitat Selection Lecture objectives: 1.Understand the adaptive value of: habitat selection, dispersal & migration, and territoriality 2.Be able to distinguish between multiple adaptive hypotheses for a given behavior

3 Where an animal chooses to live can greatly affect its fitness

4 Least tern & Habitat restoration

5 Since habitat selection is important, animals should have evolved the ability to evaluate habitat quality L Small entrance

6 So, where should an animal choose to live? But what happens to an animal’s fitness if all individuals choose the same spot? Animals must somehow distribute themselves between patches that vary in resources

7 Animals must somehow distribute themselves between patches that vary in resource # or quality

8 Example: distribution of female aphids

9 Dispersal: moving to a new home area

10 Why disperse? CostsBenefits

11 Migration is a special form of dispersal Migration – the regular (seasonal) movement back and forth between two relatively distant locations by animals

12 Why do animals migrate?

13 Animals have evolved behaviors that lower the costs of migration

14 Some birds can adjust their migratory strategy

15 To defend or not to defend? Home RangeTerritory

16 Why be territorial? CostsBenefits Bitterling (w/ mussel)

17 How does an animal establish/maintain territorial boundaries?

18 Example: Animals adjust territory size in relation to resource abundance

19 Example: Animals adjust territory size in relation to resource abundance

20 Example: well-defined boundaries reduce costs of territoriality “Good fences make good neighbors!!”

21 In territorial disputes, the territory owner often wins

22 Why does the owner often win?

23 Example: Resource-holding power in damselflies

24 Example: Benefits of a dear neighbor Fiddler crab, Uca mjoebergi Crab + neighborCrab (alone) Success in driving away intruder 88%71%