Where to live?. BIOL 3100. Sometimes you really want to get away…. Migration involves breeding site selection, stopover site selection, and non-breeding site selection. How did migration evolve in the first place?. Monarch Migration.
Where to live?
Migration involves breeding site selection, stopover site selection, and non-breeding site selection
How did migration evolve in the first place?
Monarchs have an annual migration that takes them from Canada to Mexico – however, no single individual makes a complete journey.
Most live for only 2 months; however, the last generation of summer enters diapause and may live for 7 months, flying to an overwintering site to deposit eggs.
The over-wintering generation doesn’t reproduce until it leaves the winter site in Feb/Mar
Over-wintering pops east of the Rockies may reach as far north as Texas/Oklahoma during spring migration.
It is the 2nd, 3rd, and 4th generations that actually end up in the Northern US and Canada
Use the position of the sun in the sky to calculate where to go, but also use a 24-hour circadian clock in their antennae to compensate for movement of the sun across the sky
Use the earth’s magnetic field (much like birds) as a backup to their sun compass
Heritability of migratory behaviour that is functional between multiple generations
The strength of migratory connectivity may shape our conservation priorities.
Tracking the spread of avian-borne diseases, such as bird flu, is critical for stopping the spread of infectious disease
How do we limit the spread of bird flu if we don’t know where birds are going?
Unique numbers/markers can be attached to individuals at one location and, when they are recovered, we can link locations and make migratory connections.
Satellite tracking provides extremely high resolution, but is limited to large animals and can be prohibitively expensive
Stable Isotopes and Trace Elements
Carbon – plant photosynthesis
Nitrogen – trophic level
Hydrogen – hydrologic cycle
Trace Elements – geology, contaminants
Hydrogen varies latitudinally across North America
Migratory decisions can be condition-dependent.
Birds with low fat reserves head west and fly overland toward Mexico.
Birds with high energy reserves fly straight across the Gulf of Mexico
If flying over water is risky, why fly non-stop 50-90 hours from Nova Scotia to Venezuela?
Faster, few predators, also wait for west-to-east winds to begin the journey
But, upon their return, blackpolls fly up across land. Why?