ENWC418 Lecture 12: ENWC418 Lecture 12 Migration
2 May 2018
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ENWC418 Lecture 12 Migration
• Uuestioal oe of atues ost ipessie adaptatios
• In North America, an estimated 5 billion land birds migrate to and from central and south America
annually
• A blue-winged teal banded on the St. Lawrence River near Quebec was recovered in Guiana 27 days
later = 3,300 miles
• A Lesser Yellowlegs was banded on coast of Massachusetts and shot on Martinique 6 days later =
1,930 miles
• Red Knot and Artic Tern
• The Red Knot migrates from Baffin Island to Tierra Del Fuego w/ Delaware Bay as the
primary staging area
• The Arctic Tern migrates between the Arctic and Antarctic for a total distance of 10,000
miles
• Golden Plover and Ruddy Turnstone
• The Golden plovers from Alaska migrate 2,500 miles to winter on the Hawaiian Islands
• Ruddy Turnstone flies over 650 miles /day at > 50 mph
• Bar-tailed Godwits
• Bar-tailed Godwits fly nonstop from staging groups near breeding area in Alaska to
wintering grounds in New Zealand (nearly 7000 miles)
• What is Migration?
• Migration is the predictable, seasonal movement of individuals in response to variation in
climate and / or resource availability
▪ Long distance
▪ Round trip (not one way = dispersal)
• Migration differs from NOMADISM by predictability.
▪ Nomadism is movement related to unpredictable changes in climate and resources
(crossbills)
• Irruptions = irregular movement between consistent or inconsistent locations – Invasions of
winter finches in response to severe winter
• Dispersal = movement of an individual from one breeding site to another
• Philopatry = the tendency to return to the same location in successive years
• Categories of Residency and Migration
• Residence – non-migratory
• Facultative Migration – move varying distances in different years; usually dependent on
non-breeding season conditions
• Obligate Migration – undertake, regular and predictable movements during the annual
cycle
• Nomadism – bird track environmental conditions in all seasons breeding in different
locations in different years
• Long distance: Hudsonian Godwit
• Loop- Common Cuckoo
▪ Follow clockwise path from breeding grounds to central Africa and back
▪ Loop migrations usually results from varying wind directions
find more resources at oneclass.com
find more resources at oneclass.com
• Leap Frog: Fox sparrow
▪ Leap Frog Migration – a pattern where the inds. at the extreme of the breeding
range migrate farthest
▪ Travel past birds that breed and winter in intermediate locations
▪ Sub-species in central Pacific Coast are resident
▪ Sub-species in breeding in more northern areas migrate
• Resplendent Quetzal
▪ Migrate to different elevations and slopes in Costa Rica
▪ Usually breeding in higher elevations and moving to lower elevations for
nonbreeding
▪ Altitudinal migrants are often facultative – not all inds. migrate and a given ind. may
not migrate every year
• Cost of Migration
• Cost of migration is HUGE – more than 50% of the North American migrants do not return
the following spring
▪ Of the 100 million waterfowl that migrate south annually, only 40 million returns
• Flight is energetically costly, and migration exposes birds to lethal weather events, increased
predation risk, and other hazards (buildings, towers)
• There is also a temporal cost associated with the reduced time for reproduction
• Fuel for Migration
• Many species exhibit periods of hyperphagia before and during migration to build lipid
reserves
• Fat yields 2 times more energy and water per gram than protein
• 9 Kilojoules / ga fo lipid esus • Kilojoules / ga fo potei
• Most lipid reserves are stored under the skin, in peritoneal cavity, and in muscle tissue
• Blackpole Warblers heading for South America nearly double their body mass from 11 to 20
grams
• Lipids are Labile = added to body quickly and burned very efficiently
• Stopover Areas
▪ Regular refueling is common on both spring and fall migrations
▪ Many passerines fly several hundred kilometers and then stop to refuel while others
fly until their fat reserves are exhausted
▪ Shorebirds have important staging areas like Copper River Delta in Alaska, Bay of
Fundy, and Delaware Bay
• Migratory Connectivity
• Population connectivity = the degree to which two breeding populations are connected by
dispersal and gene flow
• In a species with strong migratory connectivity all members of a breeding population winter
in the same area
• When migratory connectivity is low, individuals from different breeding populations share
the same non-breeding sites
• Navigation
• How birds find their way across large expanses of unfamiliar terrain has fascinated
ornithologists for centuries
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Enwc418 lecture 12 migration: u(cid:374)(cid:395)uestio(cid:374)a(cid:271)l(cid:455) o(cid:374)e of (cid:374)atu(cid:396)e(cid:859)s (cid:373)ost i(cid:373)p(cid:396)essi(cid:448)e adaptatio(cid:374)s. Long distance: round trip (not one way = dispersal, migration differs from nomadism by predictability, nomadism is movement related to unpredictable changes in climate and resources (crossbills) Loop- common cuckoo: follow clockwise path from breeding grounds to central africa and back. Loop migrations usually results from varying wind directions. Fundy, and delaware bay: population connectivity = the degree to which two breeding populations are connected by dispersal and gene flow. Landmarks: solar compass, stellar compass, olfactory cues, magnetic cues. Learning: visual landmarks, both diurnal and nocturnal migrants rely on landmarks (mountain ranges, coastlines, rivers, water bodies, major cities) to determine location. Landmarks often concentrate migrants acting as a funnel where large numbers of individuals occur: can provide learning opportunity for juveniles, examples, strait of gibraltar funnels eurasian migrants around the, but la(cid:374)d(cid:373)a(cid:396)ks cannot explain navigation in novel environments.
