Chapter 10 Flashcards
Migration vs Dispersal
- migration: Predictable back-and-forth movements; Repeated seasonally
- dispersal: Usually a unidirectional movement
Name the different types of dispersal
- natal dispersal
- breeding dispersal
- postbreeding dispersal
Natal dispersal
- movement between the site where an individual is born and the site where it first breeds
Breeding dispersal
- movement between one breeding site and another
Postbreeding dispersal
- typically refers to the wandering movements that some birds (e.g., herons) make after they finish breeding, but before they settle at a wintering site
Why are temperate-zone and arctic latitudes a problem? What are the three responses to this?
- Abundant resources in the summer; Limited resources and harsh climatic conditions in the winter
- 3 responses:
Migration - move to more favorable areas
Residency - with adaptations for tolerating harsh conditions
Hibernation - only documented for Common Poorwill
Understand the differences in annual adult survival, and annual reproductive success in tropical resident
annual adult survival: Do not face hazards of migration, harsh winter
HIGH (80-90%)
annual reproductive success: No seasonally abundant food source for offspring (LOW)
Understand the differences in annual adult survival, and annual reproductive success in migrant
annual adult survivial:Escape harsh winter but some die during migration
MODERATE (50%)
annual reproductive success: Seasonally abundant food source, but divert time, energy from breeding to migration
MODERATE
Understand the differences in annual adult survival, and annual reproductive success in temperate resident
annual adult survival: Endure harsh winter and restricted food supply
LOW (20-50%)
annual reproductive success: Seasonally abundant food source
HIGH
Philopatry
- Most individuals return annually to the same areas where they bred the year before
understand the different patterns of migration
seasonal variation
Residence
Facultative Migration
Partial Migrants
Obligate Migration
Nomadism
Residence
- nonannual movement at all
- common in tropics
- examples: chowchilla, wreathed hornbill, ivory-billed woodcreeper
Facultative migration
- migrate only under certain conditions
- example: northern lapwing, american robin, european blackbird
Partial migrants
- some individuals within a population
- example: In different locations, European Blackbirds (Turdus merula) are year‐round residents, facultative migrants, or obligate migrants. Even within the region where blackbirds are present year round (green), the population includes full‐time residents, facultative migrants seeking refuge and resources because conditions farther north became unsuitable, and obligate migrants that migrate south every winter regardless of conditions in the north
Oblique Migration
- Undertake predictable annual migrations to distant non‐breeding grounds
- Most songbirds that breed in the northern parts of North America, Europe, and Asia fall into this category