Lecture 8 - Migration Flashcards
define migration
movement away from and then subsequent return to the same location on a regular basis
define dispersal
is this migration?
why/when disperse?
movement away from a particular area.
no, do not return.
natal or breeding dispersal
during winter, approx how many birds in Mexica are migrants?
50%
what are duck/goose migration routes called?
describe them
flyways
-narrow and well defined
hunter band returns
songbird routes?
less known
appear to use weather fronts
how are stable isotopes used to track migration?
deuterium in feathers reflect rainfall in areas where feathers were grown
measure deuterium to hydrogen ratio of feathers
how do patterns differ between birds that soar and birds that flap?
soar -use updrafts and thermals -only fly in daytime --->obtain heat and updrafts -stay over land flap - fly over the ocean --> fewer updrafts/less turbulence - fly at night -->less heat!!
benefits to night flying?
avoid predators
feed during day
less turbulence caused by thermals and updrifts
cooler - avoid overheating
–>flight muscles generate lots of heat
- convective & evaporative cooling (no sweat glands but secrete water through skin)
-more humid = less moisture loss
what animal undergoes the longest migration?
how long?
arctic tern!
19,000km each way
how of advancements in geolocators increased our understanding of migrations?
record ambient light intensity, reveal info on sunrise/sunset!
combine light data with time recordings
satellite locators?
smaller = can go on small birds!
cheaper
but can’t transmit data (need to be retrieved)
accuracy within 185km
How did Nbound vs Sbound trip compare time wise for terns?
Nbound was almost twice as fast. corresponded with wind patterns. Need to be back for breeding - more direct
Sbound less direct, some areas where birds stopped for a bit
What are the 3 stages of migration evolution?
partial migration
migratory & resident pop’s
only migrant pop remains
What is the ancestral state?
not to migrate
example of a split btwn migrant and non migrant?
fox sparrow
hypotheses for how migration behaviour started?
lived in warm place
climate change
discuss hyp 1-lived in warm places
competition for resources –> range expansion
during warm moths, members began living in more northern warm areas
winter came - food grew scarce so temp relocated to warmer latitudes
discuss hyp 1-climate change
species lived in N all year during periods when climate was warm
as climate changed, winters eventually get too cold facing species to head south
phylogenetically most migrating species are of _____ origin
what hyp does this support?
tropic
supports H1
what are ultimate questions vs proximate questions
ult=functional or evolutionary history questions
prox= causal mechanisms or developmental questions
why does a bird migrate?
proximate and ultimate answer
P=perception of day length, hormonal triggers
U=what is the purpose and why now?
define adaptation
inheritable characteristic that gives the individual an advantage (reproductively) over others with different inherited abilities
costs of migrating?
energy
predation
getting lost
how to mitigate the costs of migrating?
energetics = V formation reduces drag starvation = get really fat the long flight OR not so fat, short flights, stopover and feed
