PSYC 311 1st Edition Lecture 17- Habitat Selection – searching for a new place to live o Why disperse? (lemming) Parental pressure Breeding area not suitable for year round habitat  Destruction/encroachment of habitat Crowding and increased costs of competition  Reproductive fitness – dispersal minimizes inbreedingo Who disperses? Phiopatric – those that stay - Males vs. females (lions) Advanced species: bonds between groups strengthened by exchange of male and females  Active competition – some habitats are superior; the fittest are usually the most successful at defending prime habitats - Predators drawn to areas with high prey densityo Types of dispersal  Density independent – due to environmental change - Fire, tornado, hurricanes  Density dependent – due to disease, decreases in food, overcrowding o Finding a habitat  Knowing locationi of resources- Important for home area and familiar area- Learning interacting with genetic background o Land marks, scent trails- Long Distance Migration o Introduction Seasonal fluctuations in temporary food supply, safety, etc. Who migrates, and why?- C/B of migration  Champion migrator = arctic tern o How do they know how to get there  Orientation – moving in a direction - Fly south for the winter- Displacement is bad news (wind, storms) Navigation – allows for correction of travel path in event of displacement - More sophisticated o Cue utilization  Visual cues (landmarks) Using the sun: sun appears to move ~15 degrees/hour- Seasonal variations in day length and angle of a point on the map relative to the sun (remember that the earth rotates around the sun)- Need for biological clock  Migratory restlessness (starlings)- Will face appropriate direction association with migration and show intentional movements when they can see the sun o Clock shift experiments (use of planetarium) Internal clock usually synced with sun location - Kramer – create discrepancy between position of the sun and internal clock o Animals change orientation to synchronize sun time with internal clock o Stars – evidence that some nocturnal travelers might orient toward Polaris Or next brightest star Betelgeuse- Use of moon is rare (moves)o Polarized light – animals distinguish between polarized bands o Geomagnetic cues  Northern geographic pole, south magnetic pole (vice versa, opposites attract)  Latitude information – how far to travel- Inclination (DIP) at poles and geomagnetic strength, greatest at poleso Birds use this cue and seem to respond to inclination with changes in dip - Ferromagnetic otoliths (detectors)- Use of GM cures is more widely used than once believedo Long distance navigation - Use until animal is within range of chemical cueso Salmon, eels, turtles o Chemical cues  Olfactory/gustatory gradients (usually in water)- Form of imprinting to environmental features C/B of migration – must eat a lot for reserves, destination habitat may have been altered, models for learning migratory routes, allows escape to more temperate areas, enhance flock fitness, flying at night better for energy expenditure o Territoriality  The most fit controls the territory  Size of territory related to quality and quantity of resources contained in territory - Rich territories are fought over  Bourgeois Strategy – individual animal defends their territory - Anti-Bourgeois