habitat preference - choosing a place to live migration

Habitat Preference - Choosing a Place to Live

MIGRATION

HABITAT PREFERENCES

1. DISPERSAL

2. MIGRATION

DispersalMigrationTerritory

Passive dispersal

Dispersal

DispersalMigrationTerritory

Definition - generally one-way and permanent movement of animals fromone place to another

Natal Philopatry vs Natal Dispersal

Dispersal

DispersalMigrationTerritory

Natal Philopatry

Costs- inbreeding depression

- increased competition

Benefits - inbreeding

- local familiarity

Natal Dispersal

Costs- energy used in dispersal

- increased predation

Benefits - reduced inbreeding

- avoid competition

- lack of local familiarity

Dispersal

DispersalMigrationTerritory

Lions - sex dependent dispersal patterns

Remain in pride

Form new pride

Transfer to another pride

Nomads

Left area

Died

Disappeared

% of lions0 100

Females

Males

Dispersal

DispersalMigrationTerritory

Inbreeding Depression

- field mice

Margulis & Altman. 1997. Anim. Beh.54: 397

% not breeding

Days since mating

Outbreeding mothers

Inbreeding mothers

Dispersal

DispersalMigrationTerritory

Inbreeding Depression

Seychelles warbler - Acrocephalus sechellensis

Dispersal distance

% r

elat

ed b

reed

ers

in

adja

cent

terr

itor

ies

Closely related r >.35) Moderately related - .1 < r <.35).7

.6

.5

.4

.3

.2

.1

0.0

Eikenaar et al. 2008 J. Evol. Biol. 21: 1106

Dispersal

DispersalMigrationTerritory

Outbreeding Depression

- song sparrow

Searcy et al, 2002

Distance apart

Dis

crim

inat

ion

Females

Males *

* * *

*

*

* = signficantly different from random

Dispersal DispersalMigrationTerritory

Searcy et al, 2002 * = signficantly different from random

Schistocerca gregaria - migratory locust

Dispersal DispersalMigrationTerritory

Searcy et al, 2002 * = signficantly different from random

Schistocerca gregaria - migratory locust

Dispersal

DispersalMigrationTerritory

SolitaryDispersing

Migration

DispersalMigrationTerritory

Recognized for long time

Migration

DispersalMigrationTerritory

Functional Classification

1. Exploratory

2. Removal

Dispersal

3. Return migration

4. One-way migration

Migration

DispersalMigrationTerritory

3. Return migration

Long range

Migration

DispersalMigrationTerritory

3. Return migration

Short range

Three wattled bellbirdProcnias tricarunculata

Migration DispersalMigrationTerritory

Components

1. Periodic timing -daily-tidal-lunar-annual - 1 - many years

Migration DispersalMigrationTerritory

Components

2. Track pattern

Loop One direction Multispecies

Migration DispersalMigrationTerritory

Components

3. Plane of movement

1. Horizontal2. Vertical

Plankton

Elk

Migration DispersalMigrationTerritory

Components

4. Geographical direction

-most are north - south

Albatross - east -west

Migration DispersalMigrationTerritory

Components

5. Direction ratio

Variation about mean direction

Migration DispersalMigrationTerritoryProcesses governing migration

W. Rowan (1925)

Junco

Treatment Response

Control Natural winter

daylength

No gonad growth

No migration

Experimental Increased

Photoperiod

(simulate spring)

Gonad growth

Northward migration

(even in winter)

Migration DispersalMigrationTerritoryProcesses governing migration

Change in photoperiod

Increased hormone secretion

Gonad maturation Migration

Preparation

Initiation

Migration DispersalMigrationTerritoryPreparation

1) Increase fat deposition

-rapid eating

-increase in stomach volume

-increase in fat load

100

80

60

40

20

0

Fat load(% of leanbody wt)

Non-migrants Short distance Mid-distance Long distance

Migration DispersalMigrationTerritoryPreparation

1) Increase fat deposition

Level of reserve can affect direction

e.g. red eyed vireo

Fat birds

Lean birds

Migration DispersalMigrationTerritoryPreparation

2) Zugenruhe - “migratory restlessness

Before onset

After onset

Migration DispersalMigrationTerritoryInitiation

Must determine a direction

1) Piloting - recognition of familiar landmarks

Migration DispersalMigrationTerritoryInitiation

Must determine a direction

2) Orienting - recognize and maintain compass direction

Migration DispersalMigrationTerritoryInitiation

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

Migration DispersalMigrationTerritoryInitiation

How do you tell an orienting from a navigating animal??

displacement Orienting(or vector navigation)

Navigating

Zonotrichia leucophrys

Throup et al, 2007. PNAS 104: 18115

Breeding grounds

Wintering grounds

Zonotrichia leucophrys

Thorup et al, 2007. PNAS 104: 18115

Breeding grounds

Wintering grounds

Boles & Lohmann, 2003. Nature 421: 60

True Navigation in Lobsters

Pagurus

Migration DispersalMigrationTerritoryInitiation

Without external cues

Cataglyphis

Food item

Nest

591 m

140 m

Migratory Cues - Sun Compass

Starling

Mirror

Sun Compass

Kramer

Clear Skies Overcast

Is there an internal clock?

Direction at 0900 under natural sky

45º

Direction at 1500 under natural sky

45º

Direction at 1500 under natural sky after biological clock is delayed by 6h

45º

Changing position of the sun in the sky - azimuth

Star Compass

Polarized light

Polarized light

Polarized light

Clear sky Cloudy sky

Magnetic field

Magnetic field

Magnetic field

Magnetic field

Migrating in groups

Naïve birds singly

Group experiment

Experienced birds singly

Migrating in groups

Energetic costs

Pelicans

Gliding Alone (50 m) Alone (1m) In formation

Wingbeats /min

•

• •100

50

10

Heart beats /min

Weimerskirch et al, 2001

Migrating in groups

Energetic costs

Pelicans

Gliding Alone (50 m) Alone (1m) In formation

Wingbeats /min

•

• • ••••• •

100

50

10

1 2 3 4 5 6

1

23 4 5 6

Heart beats /min

Weimerskirch et al, 2001

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 merulaEuropean blackbird

Migration as a conditional strategy

Turdus merula

Resident in preceding winter Migrant in preceding winter

resident

migrant

resident

migrant

Male Female Male Female