Behavioural Ecology Habitat Preference - Choosing a Place to Live
Costs and Benefits Cost - any factor that reduces reproductive success (directly or indirectly) Benefit - any factor that increases reproductive success (directly or indirectly) Strategy - a set of behavioural courses of action with a given survival value under a particular set of conditions For a successful strategy C < B Or C/B<1
HABITAT PREFERENCES 1. DISPERSAL 2. MIGRATION 3. TERRITORY Dispersal
Definition - generally one-way and permanent movement of animals from Dispersal Migration Territory Dispersal Definition - generally one-way and permanent movement of animals from one place to another Natal Philopatry vs Natal Dispersal
Dispersal Natal Philopatry Natal Dispersal Costs Migration Territory Dispersal Natal Philopatry Natal Dispersal Costs - inbreeding depression Costs - energy used in dispersal - increased competition - increased predation - lack of local familiarity Benefits - inbreeding - local familiarity Benefits - reduced inbreeding - avoid competition
Dispersal Lions - sex dependent dispersal patterns Females Males 100 Migration Territory Dispersal Lions - sex dependent dispersal patterns Remain in pride Females Males Form new pride Transfer to another pride Nomads Left area Died Disappeared % of lions 100
Dispersal Migration Territory Dispersal Migratory locust
Dispersal Migration Territory Migration Recognized for long time
Functional Classification Dispersal Migration Territory Migration Functional Classification 1. Exploratory Dispersal 2. Removal 3. Return migration 4. One-way migration
Dispersal Migration Territory Migration 3. Return migration Long range
Migration 3. Return migration Short range Three wattled bellbird Dispersal Migration Territory Migration 3. Return migration Short range Three wattled bellbird Procnias tricarunculata
Migration Components Periodic timing -daily -tidal -lunar Dispersal Migration Territory Components Periodic timing -daily -tidal -lunar -annual - 1 - many years
Migration Components 2. Track pattern Loop One direction Multispecies Dispersal Migration Territory Components 2. Track pattern Loop One direction Multispecies
Migration Components 3. Plane of movement 1. Horizontal 2. Vertical Dispersal Migration Territory Components 3. Plane of movement 1. Horizontal 2. Vertical Plankton Elk
4. Geographical direction Migration Dispersal Migration Territory Components 4. Geographical direction -most are north - south Albatross - east -west
Migration Components 5. Direction ratio Variation about mean direction Dispersal Migration Territory Components 5. Direction ratio Variation about mean direction
Processes governing migration Dispersal Migration Territory Processes governing migration W. Rowan (1925) Treatment Response Control Natural winter daylength No gonad growth No migration Experimental Increased Photoperiod (simulate spring) Gonad growth Northward migration (even in winter) Junco
Increased hormone secretion Migration Dispersal Migration Territory Processes governing migration Increased hormone secretion Change in photoperiod Gonad maturation Migration Preparation Initiation
1) Increase fat deposition Migration Dispersal Migration Territory Preparation 1) Increase fat deposition -rapid eating -increase in stomach volume -increase in fat load 100 80 60 40 20 Fat load (% of lean body wt) Non-migrants Short distance Mid-distance Long distance
2) Zugenruhe - “migratory restlessness Migration Dispersal Migration Territory Preparation 2) Zugenruhe - “migratory restlessness Before onset
2) Zugenruhe - “migratory restlessness Migration Dispersal Migration Territory Preparation 2) Zugenruhe - “migratory restlessness Before onset After onset
Must determine a direction Migration Dispersal Migration Territory Initiation Must determine a direction 1) Piloting - recognition of familiar landmarks
Must determine a direction Migration Dispersal Migration Territory Initiation Must determine a direction 2) Orienting - recognize and maintain compass direction
Must determine a direction Migration Dispersal Migration Territory Initiation Must determine a direction 3) True Navigation - identification of “home” from any direction Need a) map sense - determine location relative to goal b) compass sense - maintain direction relative to position
Must determine a direction Migration Dispersal Migration Territory Initiation Must determine a direction How do you tell an orienting from a navigating animal?? Move animal Move animal Orienting Navigating
Migration Initiation Without external cues Food item Nest Dispersal Territory Initiation Without external cues Food item Cataglyphis Nest
Sun Compass Kramer Starling
Sun Compass Kramer Clear Skies Overcast
Changing position of the sun in the sky - azimuth
Star Compass
Polarized light
Polarized light 0900 Dawn = area of darkness =plane of polarized light 1200
Magnetic field
Magnetic field
Evolution of Migration 1. Higher incidence in ephermeral or unstable habitats 2. Reproduction - allows exploitation of seasonally rich food supply 3. Predation and reproductive synchrony
Migration as a conditional strategy Turdus merula Resident in preceding winter Migrant in preceding winter resident resident migrant migrant
Passive dispersal