BIOL 1902 Lecture 7: LECTURE 7
24 Oct 2018
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LECTURE 7
Migration
- Leave because of food supply but also solves the temperature problem
- Fats power the flights (white) sandpipers double their body weight in 10 days!
o Hyperphagia-ability to eat lots of food non-stop—don’t stop eating (me)
o Hyper lipogensis – elevated state of the body converting the food into fat very
quickly allowing the birds to double their weight
- SONGBIRDS
o Travel at night, less danger
o Stopover- where they stop to feed for a few days
o Less chance of overheating (working muscles (wings) generate heat)
o Less winds at night
o Calmer. Cooler.
- Some, do however, fly during the day.
~hawks, eagles (BIRDS OF PREY)
o Larger birds, they fly on thermals (the rising calms) the rising calms of air.
Soaring (going up) then glide down to the next thermal. This is called thermal
hopping. They can often do this for hours on end without flapping their wings
even once
o Swallows
o Migrate at daytime which—feed on flying insects and need to feed as
they migrate—fast flyers and burn up a lot of fuel when they move
o Hummingbirds
o Must feed as they migrate
o Blackbirds, Blue Jays
- ONLY ABOUT HALF OF MIGRATING BIRDS MAKE IT BACK
How do birds find their way?
- Daytime navigate by sun, landforms, wind noise and other visual cues
- Nocturnal migrants use visual cues too. Moon and stars
- Both use EARTH’S MAGNETIC FIELD
o Special pigment called Rhodopsin a photo pigment in the retina, is like involved
o Really don’t know
- Geese fly by day and night. They fly in “V”s as their wings create lift, and makes flying
easier for the ones following—to conserve energy they get free lift. Each bird gets lift
then the one in front of it
PLANTS
• Big threat, ice inside the cells will kill them
• Many plants go dormant in the soil under the snow (root)
• Plants become COLD HARDY-survive where they are. Through ACCLIMATION
(equivalence to Freeze Tolerance)
o Water is drawn and evaporated from leaves
o Water is drawn out of the cells, which increases solute concentration
o Protective sugars added to cells increasing solute concentration
