Habitat Preference - Choosing a Place to Live MIGRATION

HABITAT PREFERENCES 1. DISPERSAL 2. MIGRATION 3. TERRITORY Dispersal Migration Territory

Passive dispersal

Dispersal Migration Territory Definition - generally one-way and permanent movement of animals from one place to another Natal Philopatry vs Natal Dispersal

Dispersal Migration Territory 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 Migration Territory Lions - sex dependent dispersal patterns Remain in pride Form new pride Transfer to another pride Nomads Left area Died Disappeared % of lions 0100 Females Males

Dispersal Migration Territory Inbreeding Depression - field mice Margulis & Altman Anim. Beh.54: 397 % not breeding Days since mating Outbreeding mothers Inbreeding mothers

Dispersal Migration Territory Inbreeding Depression Seychelles warbler - Acrocephalus sechellensis Dispersal distance % related breeders in adjacent territories Closely related r >.35)Moderately related -.1 < r <.35) Eikenaar et al J. Evol. Biol. 21: 1106

Dispersal Migration Territory Outbreeding Depression - song sparrow Searcy et al, 2002 Distance apart Discrimination Females Males * * * * * * * = signficantly different from random

Dispersal Migration Territory Searcy et al, 2002 * = signficantly different from random Schistocerca gregaria - migratory locust

Dispersal Migration Territory Searcy et al, 2002 * = signficantly different from random Schistocerca gregaria - migratory locust

Dispersal Migration Territory Solitary Dispersing

Migration Dispersal Migration Territory Recognized for long time

Migration Dispersal Migration Territory Functional Classification 1. Exploratory 2. Removal Dispersal 3. Return migration 4. One-way migration

Migration Dispersal Migration Territory 3. Return migration Long range

Migration Dispersal Migration Territory 3. Return migration Short range Three wattled bellbird Procnias tricarunculata

Migration Dispersal Migration Territory Components 1.Periodic timing -daily -tidal -lunar -annual many years

Migration Dispersal Migration Territory Components 2. Track pattern LoopOne directionMultispecies

Migration Dispersal Migration Territory Components 3. Plane of movement 1. Horizontal 2. Vertical Plankton Elk

Migration Dispersal Migration Territory Components 4. Geographical direction -most are north - south Albatross - east -west

Migration Dispersal Migration Territory Components 5. Direction ratio Variation about mean direction

Migration Dispersal Migration Territory Processes governing migration W. Rowan (1925) Junco TreatmentResponse ControlNatural winter daylength No gonad growth No migration ExperimentalIncreased Photoperiod (simulate spring) Gonad growth Northward migration (even in winter)

Migration Dispersal Migration Territory Processes governing migration Change in photoperiod Increased hormone secretion Gonad maturationMigration Preparation Initiation

Migration Dispersal Migration Territory Preparation 1) Increase fat deposition -rapid eating -increase in stomach volume -increase in fat load Fat load (% of lean body wt) Non-migrants Short distanceMid-distanceLong distance

Migration Dispersal Migration Territory Preparation 1) Increase fat deposition Level of reserve can affect direction e.g. red eyed vireo Fat birds Lean birds

Migration Dispersal Migration Territory Preparation 2) Zugenruhe - “migratory restlessness Before onset After onset

Migration Dispersal Migration Territory Initiation Must determine a direction 1) Piloting - recognition of familiar landmarks

Migration Dispersal Migration Territory Initiation Must determine a direction 2) Orienting - recognize and maintain compass 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

Migration Dispersal Migration Territory Initiation How do you tell an orienting from a navigating animal?? displacement Orienting (or vector navigation) Navigating

Zonotrichia leucophrys Throup et al, PNAS 104: Breeding grounds Wintering grounds

Zonotrichia leucophrys Thorup et al, PNAS 104: Breeding grounds Wintering grounds

Boles & Lohmann, Nature 421: 60 True Navigation in Lobsters Pagurus

Migration Dispersal Migration Territory Initiation 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

Clear skyCloudy sky

Magnetic field

Migrating in groups Naïve birds singly Group experiment Experienced birds singly

Migrating in groups Energetic costs Pelicans GlidingAlone (50 m) Alone (1m) In formation Wingbeats /min Heart beats /min Weimerskirch et al, 2001

Migrating in groups Energetic costs Pelicans GlidingAlone (50 m) Alone (1m) In formation Wingbeats /min 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 merula European blackbird

Migration as a conditional strategy Turdus merula Resident in preceding winterMigrant in preceding winter resident migrant resident migrant MaleFemaleMaleFemale