1. Unit 6
Avian Behavior

2. Annual Cycles Birds face seasons of stress and seasons of opportunity
Caused by month to month changes in day length, climate and resources in their habitats

3. Permanent Residents
Birds that do not migrate face three main, sequential tasks they must perform
Breed
Molt
Survive until the next breeding season

4. Migrants Migrants have special tasks to worry about Breed Molt
Flock and fuel
Migrate

5. Biological Clocks
Devices found in the cells of birds that control the release of hormones and other chemicals that regulate metabolism, reproduction and behavior

6. Circadian Rhythms
Every individual has an intrinsic rhythm approximately 24 hours in length in which the rate of metabolism, body temperature, and level of alertness fluctuate in predictable ways

7. Circannual Cycles
Internal rhythms approximately one year in length that determine activities throughout the year
Due to photoperiod (the # of hours of light and dark in day)
Birds monitor day length using special receptors in the hypothalamus of the brain

8. Breeding Seasons
Over many generations, individual species have found the best time for the group to breed
Timing of breeding deals with food supply for parents and young, availability of nest sites, location of favorable climates, and times of low predatory risk
However, this does not account for unpredictable things like drought or parasites

9. Energetic Cost of Reproducing
Breeding must be timed so that food availability exceeds that of normal activities
Birds must molt (breeding plumage) set up territories, mate and find food for young, then molt again
Usually in winter months, there is only enough food for self-maintenance