Migration and Navigation. Sci Show Assignment. Migration is. Migration Relatively long-distance two-way movements

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1 Migration and Navigation Migration is Sci Show Assignment Due by 11am, April 28th! Password for the youtube site is: animalbehavior Updated instructions on how to access the youtube channel are posted on the course website Any questions? Animals migrate in response to changes in the environment Migration Relatively long-distance two-way movements the seasonal (temporary) movement b/w distant sites Steve McSweeney

2 Many bird examples 19,000 km! Migration and changing resources some bats migrate to hibernacula seals often migrate twice to feeding grounds each year gnu head north during dry season baleen whales migrate to tropics In the Serengeti, mammals appear to track available biomass of grass and its quality

3 Homing by Pacific salmon * * * * Olfactory imprinting * Salmon migrate to the ocean for 3-5yrs to feed before returning to natal stream to spawn Evidence of migration costs Costs of Migration 1. Must accumulate large energy stores 2. Excess mass limits evasive ability 3. Journey may expose animal to predators & risk of drowning Benefits of Migration 1. Adaptive response to temporal variability in climate & resource availability Body condition affects migratory route in redeyed vireos e.g. birds come north to capitalize on longer day-length e.g. some whales migrate to tropics to allow their calves to conserve energy

4 Resource variation and migration in neotropical birds Research question: What factors are important in determining whether a species migrates or not? (Boyle & Conway 2007) Hypothesis: Migration evolved to allow individuals to: (1) take advantage of spatial variation in conditions and (2) avoid seasonal resource depression at different locations Prediction: Species exposed to high degree of fluctuation in environmental conditions and resources will be more likely to migrate than species that live in more stable resource environments Resource variation and migration in neotropical birds Methods: Collected previously published data on 300 species in Tyranni For each species, determined: Migrant or sedentary Insectivore or frugivore Habitat use (tropical forest habitats more stable than nonforest habitats) Resource variation and migration in neotropical birds Results: Insectivorous species in forest habitats were less likely to be migratory than non-forest species No relationship between habitat type and migration in frugivorous species Conclusion: Fluctuations in resource levels and environmental conditions can affect migratory behavior The evolution of migration If some individuals in a population have higher fitness when migrating, then population may exhibit partial migration If all individuals who migrate have higher fitness, then population becomes migratory

5 Maintenance of polymorphism in migratory behavior Migratory behavior could be a fixed, genetic trait, and frequency-dependent selection maintains the polymorphism Migratory behavior is dependent on individual condition Navigation: How do animals find their way? Animals use multiple compass systems to determine direction Orientation Determination and maintenance of a proper direction Navigation Determining a particular location and moving toward it

6 Animals use multiple compass systems to determine direction Figure Whale migration. (a) Gray whale. (b) Whale migration route along the North American coast. Blue indicates southbound migration and orange indicates northbound migration. Orientation Determination and maintenance of a proper direction Navigation Determining a particular location and moving toward it Sun compass Use of sun for orientation Star compass Use of stars or constellations to orient Geomagnetic compass Ability to orient using the earth s magnetic field From%Nordell%and%Valone,%Animal'Behavior:'Concepts,'Methods,'and'Applica7ons,% %2014%by%Oxford%University%Press%% Monarch butterfly migration

7 Bicoordinate navigation in birds Research question: Do birds display bicoordinate navigation? (Chenetsov, Kishkinev, & Mouritse 2008)? Bicoordinate navigation: Ability to identify a geographic location Mental map Bicoordinate navigation in birds Methods: Eurasian reed warblers (Acrocephalus scirpaceus) Migrate between sub-saharan Africa and Eurasia Captured birds during spring migration Displaced half 1000 km east Bicoordinate navigation in birds Methods: Placed in Emlen funnels to measure orientation

8 Bicoordinate navigation in birds Geomagnetic compass Results: Displaced birds oriented to northwest to compensate for being displaced Conclusion: Eurasian reed warblers display bicoordinate navigation Navigation and magnetic maps in sea turtles Research question: Do sea turtles use the earth s magnetic fields for navigation? (Lohmann et al. 2001) Navigation and magnetic maps in sea turtles Methods: Juvenile loggerhead sea turtles (Caretta caretta) Exposed to three magnetic fields Measured orientation and movement

9 Navigation and magnetic maps in sea turtles Results: All turtles oriented to appropriate direction Conclusion: Sea turtles can use the earth s magnetic field to orient in different directions, and this ability is inherited, not learned Figure Turtle orientation apparatus. Diagram of the apparatus used to characterize orientation direction of sea turtles. The magnetic field inside the apparatus can be changed (Source: Lohmann 1991). From%Nordell%and%Valone,%Animal'Behavior:'Concepts,'Methods,'and'Applica7ons,% %2014%by%Oxford%University%Press%% Figure Turtle orientation. (a) Control turtles attempted to move north-northeast. (b) When the magnetic field was reversed, turtles attempted to move toward the new position of magnetic north-northeast. Each dot represents data for one turtle, and the mean direction is indicated by the arrow (Source: Lohmann 1991). Figure Pigeon magnetoreception. When small magnets are placed on their body, pigeons have trouble orienting properly. From%Nordell%and%Valone,%Animal'Behavior:'Concepts,'Methods,'and'Applica7ons,% %2014%by%Oxford%University%Press%% From%Nordell%and%Valone,%Animal'Behavior:'Concepts,'Methods,'and'Applica7ons,% %2014%by%Oxford%University%Press%%

10 Quick Review In an ultimate sense, why do animals disperse? a. To avoid competing with kin and/or conspecific competitors of higher-quality than themselves. b. To obtain mates with whom they are not closely related. c. To capitalize on seasonal food abundance and favorable climatic conditions. d. all of the above e. both a and b Quick Review A young male lemming emigrates from the area where he was born and permanently occupies a new meadow far away. The male has exhibited a. natal migration b. breeding migration c. natal dispersal d. breeding dispersal e. philopatry Quick Review The tendency for offspring of closely related parents to have lower fitness than offspring of genetically unrelated parents is called. Territoriality and Habitat Selection a. intraspecific competition b. sex-biased dispersal c. philopatry d. inbreeding depression e. selfish herd

11 Territory A territory is An area defended to obtain exclusive access to the resources it contains a defended space Home range Costs 1.??? Areas of repeated use that are not defended from conspecifics Benefits 1.??? Territoriality A territory is a defended space Costs 1. reduced feeding rates 2. injury risk 3. predation risk associated w/ displays 4. less time & energy for parental care Benefits 1. exclusive access to food, shelter or mates When is it beneficial? 1. When limited resources are clumped and ephemeral? 2. When limited resources are uniformly distributed in time and space?

12 Territoriality Far from universal Beneficial when a limited resource is uniformly distributed in time & space Red-winged blackbird