20267 AcaDec Science Section 4 Terms & Conditions

oi bruv study up

Migration

the act of animals moving from one region to another

obligate migrators

migrators that must migrate (as opposed to kinda maybe being able to stay there); inhospitable environments usually render it necessary. These animals use their biological instincts more to migrate (as opposed to the current conditions)

no migration → no pass on genetics.

faculative migrators

animals that can choose to migrate or not depending on local conditions (most often to more favorable temperatures year-round). These animals rely more on their climate to dictate migration, not their biological instincts.

partial migration

individuals choose to only migrate along their way partially. More common than complete migration. Allows unmigrated to live if migrated die off.

resident

animals that choose not to migrate even though other members might migrate. fish/bird/insect

magnetoreception

animals’ usage of the earth’s magnetic field to navigate. When solar flares disrupt the Earth’s magnetic field during migration, it can send migrating animals temporarily off course.

Birds have a very strong innate internal compass that directs their migrations. However, researchers have found that even with this innate ability, young animals making their first trip are more likely to get lost than older animals. Its really important guys & its kinda learned

quorum response

probability that an animal will behave in a certain way based on the number of other individuals who have already decided to do the behavior. A consensus will be reached.

The quorum response does not depend on a specific number of individuals doing a behavior but instead is a mathematical probability that a behavior will occur

olfactory cue

an odor molecule that represents something of specific importance to the animal. Fish/birds. Place of birth smells different type

Diel vertical migration (DVM)

the nightly migration of animals to the surface of the ocean. Usualmente more sunlight penetrates the water near the surface durante el dia, making it warmer and allows more photosynthesis. Many predators though, so small invertebrates go down lo and hit da floor when the sun’s out. so dem fish & zooplankton go out at night and also reduce their UV light.

biological carbon pump

excess carbon is removed from the atmosphere and trapped deep underwater. Comes from the zooplankton sinking and dying

dispersal

animals can most certainly leave and find a new territory further from where they were born. Avoids inbreeding & competition. NOT considered migratory behavior; animals that disperse are doing less than migrating & move less predictably.

Evolution of migration

dawg noone knows. Migration was observed 250k years ago & migration did not evolve spontaneously. It’s partially genetic and can also occur in captivity. Biological clocks can help.

Where is migration

Rare @ equator. Think about it—the temperatures are same year round and lots of resources. More dramatically changed habitats are prone to have animals that migrate.

Aristotle

believed that the barnacle goose spawned from gooseneck barnacles b/c no nests were found out in England. Lo and behold there’s migration.

Fat

most animals stock up on this before migrating

Benefits of migration

bird isolation!! Bird go away from predator to gestate. Small bird need calcium. Warm climate has calcium. Win win!!!

also traveling in numbers is scary (to others)

And also plant diversity because carry pollen everywhere

Also elephant seals come to ONE safe spot to mate so the kids safe and the adults meet each other to get fweakie (as opposed to finding another rare seal in open ocean)

Downside of migration

Requires a lot of energy. Animals inhibit reproductive systems. AKA male gardener warbler shrinks its parts.

More complex migration, bigger animal brain

Chinook salmon

travel from a freshwater river in which they are born to the ocean, where they mature, before migrating back to breed in their original freshwater river at the end of their life cycle

internal cue

triggers migration and hormones and allat

seasonal rhythms

Animals can use several seasonal cues to determine the optimal time to leave on their migration

animals that travel only underground

don’t migrate.

the closest comparable behavior is that seen in invertebrate animals that change the depth at which they burrow depending on the weather, but this is not typically considered a migration as there is no dramatic change in environment

largest over-land migration

great Nile migration in which multiple species of antelope, totaling approximately six million individuals, travel over a thousand miles across South Sudan

you can imagine the things that it does to the environment

American eel

weird type of migration; was considered several species throughout their life cycle before this guy named johannes discovered that they reproduced in the Sargasso Sea

Humpback whales

They travel from the equator, where they breed in the winter, to either the North or South Pole during the summer months to feed