Jim Briskie Lectures Flashcards
Define “proximate”
Proximate explanations include developmental and causation explanations. They focus on mechanisms, the “how”.
Define “ultimate”
Ultimate explanations include evolutionary and survival value explanations. They focus on adaptation and evolution, the “why”.
Define migration
Regular, usually seasonal, movement of all or part of an animal population to and from a given area. Typically a round-trip event with predictable movements between breeding & non-breeding ranges.
How do Bar-Tailed Godwits migrate?
Bar-tailed Godwits fly 11,500km during eight days non-stop from Alaska breeding grounds to overwinter in NZ.
How do Monarch butterflies migrate?
Monarchs fly >9000 km in a multi-generation migration.
Define altitudinal migration
Migration to high altitudes to breed and return to low altitudes for non-breeding season.
Define irruptive mirgation
Migrating periodically in response to rainfall.
Define partial migration
Migration of only a portion of a species.
How is banding used in migration?
The invention of bird bands meant it was possible to follow individuals over their life cycle and find out where they go on migration.
How is radar used in migration?
Swarms of migrating birds can be seen on radar images.
How are isotope ratios used in migration?
Hydrogen isotope ratios (which correlate with local precipitation and becomes incorporated into feathers during moult) can demonstrate origins of bird species.
How are trackers used in migration?
The miniaturisation of tracking devices has allowed us to track individuals with detail and accuracy (geolocator). Geolocators can track an animals location within 50km using the sunlight time and date.
What is a downside of using geolocators?
Having to recapture the same bird to get the data of the tracker.
Define homing
Homing is an animal’s ability to find their way home. This ability decreases with increasing displacement distance. Homing is primarily a result of familiarity with area.
What is navigation by piloting?
Some animals learn features of their environment (landmarks) and use there to orientate and navigate their way home.
What is navigation by path integration?
Some animals keep track of all turns and speed on an outward, integrating this information to make a straight line return home. If displaced at start of return trip, it runs parallel to the one it would have taken.
What is navigation by odour cues?
Some animals learn the “odour” of their stream and use this for homing.
What is navigation by celestial compass?
Some animals navigate using stars and/or sun as a compass. They need to determine direction and distance.
What is an “Emlen” funnel?
An Emlen funnel is a bird cage shaped like an inverted cone, used to study bird behaviour, in particular birds’ migratory instincts.
What is navigation by sun compass?
Some animals use the Sun’s position in the sky as a directional guide.
What is navigation by magnetic compass?
Some animals use the earth’s magnetic field to orient.
What are the benefits of migration?
- Avoid food shortage
- Exploit temporarily favourable conditions
- Escape disease
What are the costs of migration?
- Energy
- Predation risk
- Exposure to new diseases and parasites
Define dispersal
A more or less permanent movement of an individual from one area to a new area. Usually juvenile moving away from its natal area.