Emily Dickinson

2. EmilyDickinson

3. Why do birds migrate? • Migration is a strategy to take advantage of seasonally abundant food supplies • Weather and photo-period are triggers DEC NOV JAN OCT FEB SEP MAR AUG APR MAY SNOW BUNTING

4. MIGRATION STRATEGIES Complete Migration • All individuals leave the breeding areaafter raising their families • Most complete migrants breed in temperate northern climates • Many complete migrants travel incredible distances between breeding andnon-breeding habitats Cerulean warbler Wilson’s plover Stilt sandpiper

5. MIGRATION STRATEGIES Partial Migration • Seasonal movement by some, but not all, individuals away from breeding area • Some overlap of breeding & non-breeding ranges Red-tailed hawk Herring gull Bewick’s wren

6. MIGRATION STRATEGIES Irruptive Migration • Not seasonally or geographically predictable • Distances and number of migrants areunpredictable • Food specialists leave the boreal forests for more southerly ranges when food isn’t available Pine siskin Red-breasted nuthatch

7. BANDINGUS Fish and Wildlife Service BirdBanding Laboratory RADAR (NOAA)Several years ago, researchers at Cape May counted 14 million birds in one night RADIO TELEMETRYCarl Safina followed a single radio-tagged albatross throughout its range MOON WATCHINGRequires a full moon, a comfortablechair and binoculars How dowe study migration?

8. How dowe study migration? CHRISTMAS BIRD COUNT 52,471 Number of participants 1900-2000

9. THE BASICS OF FLIGHT Anatomy of Flight • A fused sternum with a “keel” provides the attachment points for the flight muscles.

10. THE BASICS OF FLIGHT A flap is a flap • Flight feathers are asymmetrical to allow them to change shape during flight • A wing must allow air to pass through it on the up-stroke

11. Airflow LIFT DEALING WITH DRAG Lift & dealing with drag • Lower air pressure above and higher pressure beneath wing creates lift • During flight, air currents coming off the trailing edge of the wing create eddies which cause drag Eddy = DRAG Lower pressure Wing cross-section Higher Pressure

12. DEALING WITH DRAG Wing slotting One way to reduce the drag causedby these eddies is to break them up into smaller eddies. Primary feathers create smaller eddies = less drag

13. DEALING WITH DRAG Ground effects Flying very close (within a wing length) to a body of water allows the rippled surface to absorb the air currents coming off the trailing edge of the wing, reducing drag.

14. THE BASICS OF FLIGHT Powered • Characterized by continuous flapping • Results in a level course through the air • Examples: sandpipers, ducks, geese, rails and hummingbirds

15. THE BASICS OF FLIGHT Bounding • Birds flap in short bursts to gain altitude, and then descend with wings folded against the body • Bounding flight results in constant climbingand descending • Examples: warblers, vireos, small woodpeckers, orioles, robins and tanagers

16. THE BASICS OF FLIGHT Partially powered gliding • Partially powered gliding birds alternate between flapping their wings and holding them extended • Small hawks use flapping to fly between thermals • Examples: cranes, swallows, swifts, pelicans, and shearwaters

17. SAILPLANE 60:1 ALBATROSS 20:1 HAWK 10 to 13:1 MONARCH BUTTERFLY 3:1 THE BASICS OF FLIGHT Gliding Gliding birds keep their wings extendedand ride rising currents of warm air tostay aloft. They flap only to regain altitude. Ratio measures horizontal distance to vertical drop

18. Route finding • Birds navigate by: visual landmarks, the sun, moon, stars, and routes learned from other birds • Birds also have an internal compass which issensitive to the Earth’s magnetic field • Migrating birds will maintain a true compass heading STARS MAGNETICNORTH MOON SUNRISE WINDS LANDSCAPEFEATURES UV LIGHT WEATHER SMELLS SOUND

19. 28-50 COMMON LOON 32-46 OSPREY 30-44 BROAD-WINGED HAWK 28-40 GOLDEN PLOVER 22-32 SEMI-PALMATED PLOVER 22-30 BALTIMORE ORIOLE BLACKPOLLWARBLER 15-23 How fast? Birds usually select the mostefficient flight speeds. 0 10 20 30 40 50 mph

20. How long? • Migrants using powered flight regularly cross stretches of open water like the Gulf of Mexico (500 miles) • Others flap continuously for as long as 70 hours • Examples: Ruby-throated hummingbird, Wood thrush and Blackpoll warbler

21. How far? NORTH AMERICAN MIGRATION FLYWAYS Atlantic FlywaysMississippi Flyways Central FlywaysPacific Flyways

22. How far? 7,000 miles one way Red KnotFlies from Argentina to Brazil, to the Delaware Bay,to the Arctic.

23. How far? 2,500 to5,000 miles one way Blackpoll warblerWinter in South America, and flyto the Caribbean,and then to northern breeding grounds.

24. Some fly across the Gulf of Mexico. (500 miles nonstop) How far? HummingbirdsWinter in Central America and fly as far north as Canada.

25. How far? 7,000 miles one way Blue-winged TealWinters in South America, and breeds in northern plains

26. DAY OR NIGHT? Diurnal migrants • Most birds which rely on gliding or flap& glide flight are diurnal migrants • The chief benefit of daytime flight is thermals – rising currents of warm air that provide lift

27. DAY OR NIGHT? Nocturnal migrants • Many birds which use powered flightare nocturnal migrants. Why…? • Night flying helps birds avoid predators • Other benefits include calmer, more stable air

28. Fat is the currency of migration • Fat is the most important fuel for migration • Many species double their weight with fat fuel for migration Typical Body Fat: PRE-MIGRATION Shorebird Songbird Hawk 66% 70% 15%

29. Fat is the currency of migration RED KNOT BODY FAT 3% 66% PRE-MIGRATION(Brazil) POST-MIGRATION(Delaware Bay)

30. Re-fueling stations are critical When a Red Knot arrives at the Delaware Bay,in two weeks it must increase its body weightby 60% to complete the trip to its arctic feeding grounds. The additional weight must be in the form of fat… A 175 lb man who wants to gain 105 lbs (60%) in two weeks would have to eat 46 Big Macs per day for 14 days… …and turn itall into fat!

31. Bay ofFundy, ME James Bay,Canada Gray’s Harbor,WA DelawareBay, MD Platte River,NE San FranciscoCA CheyenneBottoms,KS Copper RiverDelta, AK Birds rely on the samere-fueling stations Stopover places provide abundant foodfor re-fueling needed by shorebirds to complete migration, as well as roosting places.

32. Threats to migration • Loss of non-breeding ranges due to agricultureand seaside development • The destruction of the tropical and boreal forests • Habitat fragmentation The biggest threat to migration is habitat loss

33. Everythingin the worldis connected to everything else • Migratory routes are the invisible lines ofconnection which show us how people,places, and wildlife depend on each other • Migration tells us about our physicaland spiritual health

34. Sources & further reading Ornithology Frank B. Gill, W.H. Freeman & Co, 1995 The Random House Atlas of Bird MigrationJonathan Elphick, ed., Random House, 1995 The Flight of the Red KnotBrian Harrington, W.W. Norton & Company, 1996 How Birds MigratePaul Kerlinger, Stackpole Books, 1995 The Audubon Encyclopediaof North American BirdsJohn K. Terres, Alfred A. Knopf, 1982 Living on the WindScott Weidensaul, North Point Press, 1999

35. Connecting People with Nature